DEVELOPMENT OF A RAPID METHOD FOR THE

DETERMINATION OF FIBER CONTENT IN

POLYESTER/COTTON BLENDS

by

Ellen Louise Sours, B.S. in H.E.

A THESIS

IN

CLOTHING AND TEXTILES

Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

IN

HOME ECONOMICS

Approved

Accepted

August 1983

ACKNOWLEDGMENTS

The author wishes to thank Dr. Samina Khan for serving

as chairperson of the thesis committee, and for her contin­

uing support throughout this project. I would like to thank

Dr. Patricia Horridge for her constructive criticism and

attention to detail. Dr. Christopher Lupton of the Textile

Research Center gave generously of his time, energy and

experience. Without him this project would never have been

undertaken. I would also like to give my special thanks to

Bob Wyatt of the Textile Research Center for his gifts of

time, space, supplies, statistical counselling and humor. *

Finally, niy sincere thanks to the entire staff of the

Textile Research Center for their kindness and helpfulness

throughout my stay there.

11

TABLE OF CONTENTS

ACKNOWLEDGMENTS ii

ABSTRACT v

LIST OF TABLES vi

LIST OF FIGURES viii

CHAPTER

I. INTRODUCTION 1

Statement of the Problem. 3

Objectives of the Study 3

Hypotheses 4

Scope and Limitations 4

Definitions of Terms 5

II. REVIEW OF THE LITERATURE 9

Analysis of Blend Compositions . . . . 9

Fiber Properties 11

Disperse Dyes 12

Thermosol Method 13

Colorimetric Measurement 15

III. PROCEDURE 22

Pilot Study 22

Major Study 23

IV. ANALYSIS OF DATA 41

Fiber Blend Analyses-Dissolution Test Results 41

Fiber Blend Analyses-Color imetric Measurement 45

1 1 1

V. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS . . . . 64

Summary 64

Conclusions Related to Objectives 65

Conclusions Related to Hypotheses 68

Recommendations for Further Research . . . 69

LIST OF REFERENCES 71

APPENDICES

A. STATISTICAL ANALYSIS EXPLANATION 74

B. FIBER CONTENT-COLORIMETRIC MEASUREMENT . . . . 79

IV

ABSTRACT

Methods were developed to accurately and quickly

determine the polyester fiber proportions present in poly­

ester/cotton blends. The results of the developed techniques

were compared to those obtained using the American Association

of Textile Chemists and Colorists (AATCC) Test Method 20A,

a sulfuric acid dissolution technique. Six fabric blend

levels and eleven fiber blend levels were used to develop

the methodology. The samples were dyed using sublimation

techniques and disperse dyes. Reflectance data were utilized

in developing simple linear regression equations to predict

polyester content. In some cases, the polyester contents

of blends as determined by the newly developed methods

showed no significant differences (a< .05) when compared

with the polyester contents of the same samples as determined

by the AATCC Test Method. Blend levels predicted by the

sublimation techniques had standard errors of the mean that

fell within the accepted + 3% range as required by the

Federal Trade Commission for truth in labeling. The

developed methods provide rapid and easily executed tests

for determining polyester fiber blend proportions in poly­

ester/cotton blends.

v

LIST OF TABLES

Table Page

1. FABRIC CONSTRUCTION PROPERTIES (Of Polyester/Cotton Blend Fabrics used in this Study) 26

2. POLYESTER CONTENT (Of Polyester/Cotton Blend Fabrics

used in this Study) 26

3. COTTON FIBER PROPERTIES 27

4. POLYESTER FIBER PROPERTIES 27

5. SCOURING AND BLEACHING OF POLYESTER/ COTTON BLEND FABRICS 31

6. FIBER ANALYSIS (AATCC Test Method 20A) 43

7. FIBER ANALYSIS (Tetrachloroethane Method) 4 6

8. SIMPLE LINEAR REGRESSION EQUATIONS (y = ax + b> (y = Polyester Content, x = A E ) . . . 47

9. SIMPLE LINEAR REGRESSION EQUATIONS (y = ax + b) (y = Polyester Content, x = K/S) . . 48

10. CONFIDENCE LIMITS OF SUBLIMATION TECHNIQUES FOR DETERMINING POLYESTER CONTENT IN POLYESTER/COTTON BLENDS BY AE . . . . 51

11. CONFIDENCE LIMITS OF SUBLIMATION TECHNIQUES FOR DETERMINING POLYESTER CONTENT IN POLYESTER/COTTON BLENDS BY K/S . . . . 53

12. COEFFICIENTS OF VARIATION (Comparison of AE, K/S, AATCC and Tetrachloro­ethane Determination of Polyester Techniques) 56

13. ANALYSIS OF AATCC TEST METHOD AND SUBLIMATION TECHNIQUES (t-Test for Statistical Significance) 58

14. COMPARISON OF DESIZED, AND SCOURED AND BLEACHED FABRIC (t-Test for Statistical Significance) . 61

vi

Table Page

15. PREDICTED POLYESTER CONTENT OF "UNKNOWN" FIBER BLEND (Simple Linear Regression Analysis) 62

16. COMPARISON OF "UNKNOWN" TO KNOWN POLYESTER CONTENT (t-Test for Statistical Significance) . 63

17. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 1-Disperse Blue (2% w/w), Benz/Desized Fabric) 80

18. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 2-Disperse Blue (1% w/w), Benz/Desized Fabric) 82

• 19. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 3-Disperse Blue (3% w/w), Benz/Desized Fabric) 83

20. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 4-Disperse Red (2% w/w), Benz/Desized Fabric) 84

21. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 5-Disperse Blue (2% w/w), Benz/Fiber) 85

22. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 6-Disperse Blue (2% w/w), Benz/Bleached Fabric) 87

23. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 7-Disperse Blue (2% w/w), Iron/Desized Fabric) 88

24. FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 8-Disperse Blue (2% w/w), Iron/Fiber) 89

25. FIBER CONTENT-COLORIMETRIC MEASUREMENT ("Unknown" Fiber Blends) 90

vii

LIST OF FIGURES

Figure Page

1. EXPERIMENTAL DESIGN 25

2a. THE BENZ UNIT 34

2b. SC?:SMATIC DRAV:iNG OF BENZ UNIT 34

3. METHODS OF FIBER CONTENT DETERMINATION 42

Vlll

CHAPTER I

INTRODUCTION

Fabrics made from blends of polyester and cotton have

largely replaced fabrics composed of 100% polyester, nylon

or cotton fibers. Polyester and cotton blends are used in

shirts, rainwear, leisurewear, workwear, sheets and home

furnishing textiles. Factors that contribute to the popu­

larity of this fiber blend compared to 100% cotton are in­

creased abrasion resistance, better wrinkle resistance,

higher tear resistance, better shrinkage control and ease

of maintenance (13:30).

In order for the consumer to be able to make intelligent

decisions about the purchase and care of a textile product,

which may be a fiber blend, labeling of most textile products

is required by the Textile Fiber Products Identification Act

(TFPIA) initiated in 1960. Some of the information that

must accompany a textile product, as stipulated by the TFPIA,

includes the generic name of the fiber or fibers present in

the fabric and the proportion of fiber content by weight.

The Federal Trade Commission (FTC) requires that actual

blend percentages be accurate to within 3% of the composi­

tion stated on the label (21:44). This fiber blend pro­

portion information is required in industry by the economist

and technologist, in education by those involved in research,

by practitioners, and by the concerned consumer (27). To

1

date, the accepted method for quantitatively determining

the composition of fiber content in polyester/cotton blends

is the test procedure outlined by the American Association

of Textile Chemists and Colorists (AATCC) Test Method 20A,

1981-1982, 10.4 (2:46-51). This gravimetric testing pro­

cedure is a lengthy operation involving the use of a strong

acid and requiring five to six hours to perform. A study

of related literature has indicated that all existing

methods for this procedure involve the use of solvents that

are corrosive (70% sulfuric acid), expensive (heraxfluoroiso-

propanol) and/or toxic (tetrachloroethane).

A proposed alternative to the dissolution/gravimetric

analysis of blend compositions involves dyeing and subsequent

colorimetric evaluation of the fabric. The Thermosol method

is well suited to dyeing the polyester portion of polyester/

cotton blends. This method is dependent upon the ability of

disperse dye molecules to sublime into the polyester fiber

under the influence of dry heat. It is a rapid, simple dye­

ing procedure that can be simulated in a laboratory situation

with a minimal amount of equipment. In an applied commercial

situation, the specialized color measuring equipment would

normally be available since most manufacturers today own or

have access to some type of colorimeter.

statement of the Problem

The study was conducted to determine if an accurate,

nongravimetric method for determining the polyester fiber

composition in polyester/cotton blends was feasible. The

study was designed to be applicable in the research, testing

and industrial (e.g., quality control) environments uti­

lizing equipment and materials normally found in those situ­

ations. The process was designed with speed, ease of

execution, and accuracy of the procedure as important

considerations.

Objectives of the Study

The specific objectives of the study were as follows:

1. To develop a rapid and accurate method for the de­

termination of polyester fiber blend levels in polyester/

cotton blends, and to determine if this predicted polyester

content is within the range of accuracy as stipulated by

the FTC.

2. To standardize a rapid Thermosol dyeing method

using as the source of heat both a Benz laboratory curing

and drying apparatus and a household type iron.

3. To determine if disperse dyes having medium to high

energies could be used interchangeably in the procedure.

4. To develop simple linear regression equations re­

lating color to fiber content from data collected from.

intimately blended, dyed polyester and cotton fabrics and

fibers.

5. To determine the polyester content of polyester/

cotton fiber blends of unknown composition using a Thermosol

method, and to compare the results to those determined by

gravimetric measurement.

6. To compare the accuracy of the AATCC Test Method

20A to the accuracy of the tetrachloroethane test method for

the determination of polyester content in blends.

Hypotheses

The following hypotheses were tested:

1. There are significant differences between the

Thermosol techniques and the AATCC Test Method 20A in de­

termining the polyester content in desized polyester/cotton

blend fabrics.

2. There are significant differences between the

polyester content in desized polyester/cotton blend fabrics

compared to the polyester content in scoured and bleached

polyester/cotton blend fabrics as determined by the Thermosol

techniques.

Scope and Limitations

The results of this study will be applicable only in

those instances where the test methods are exactly dupli­

cated. The findings of this study will not be directly

transferable to other fiber types, fabric constructions or

dyeing procedures. The study will establish a methodology

for the analysis of undyed, polyester/cotton blends and

provide suggestions for future research.

Definition of Terms

The following specialized terminology has been used.

1. Absorption: attraction and holding of molecules,

gases or liquids within a fiber, filament, yarn or material

(25:2) .

2. Adsorption: adhesion of gases or liquids to the

surface of a substrate (25:6).

3. Agglomerate: a loose assembly of primary dye par­

ticles or aggregates in contact with one another at their

corners and edges only (24:36).

4. Aggregate: an assembly of primary dye particles

the surfaces of which are close together.

5. Blends: two or more different fibers combined in

the same yarn or fabric, in this instance polyester and

cotton. Blended fabrics are those made of yarns in which

two or more fibers are mixed before the yarn is spun. Com­

bination fabrics contain yarn which are composed of differ­

ent fibers.

6. Colorants: dyes and pigments applied to a fabric

to alter the light absorption quality (color) of the fabric

or fiber.

7. Colorimeter: instrument which is capable of deter­

mining the proportions of the primary additive lights which

are necessary to match the color reflected or transmitted

by the sample under investigation (34:668).

* ^•^CIELAB* ^ num.ber derived by calculation to indi­

cate the total color difference between a standard and a

sample.

9. Desize: to remove the sizing material (e.g., starch

or polyvinyl alcohol) which is often applied to the warp

yarns prior to weaving.

10. Disperse Dyes: class of dyes that are substantially

water insoluble and are used to dye synthetic and man-made

(hydrophobic) fibers.

11. Dye Exhaustion: during wet processing, the ratio

at any time between the amount of dye taken^ up by the sub­

strate and the amount originally available (7:54).

12. Gravimetric: pertaining to measurement by weight.

13. K/S: a ratio (value) developed for color computa­

tion based on the relationship of reflectivity and colorant

concentration; it is proportional to the concentration of

dye in the fiber.

14. Simple Linear Regression Equation: a mathematical

equation for predicting the value of a dependent variable

when given the value of an independent variable using the

linear least squares model.

15. Luminosity: quantity of light reflected or emitted

per unit area of the surface (34:657). Luminosity may also

be thought of in terms of the Munsell definition of value.

16. Migration: the movement of a dye from one area of

a dyed material to another area, this may also include move­

ment of dye from a dyed to an undyed area, or movement of

dye from the fabric to the dye solution and back into the

fabric.

17. Primary particles: dye particles that can be indi­

vidually observed under a microscope. They are the build­

ing blocks for aggregates and agglomerates (24:36).

18. Reduction clear: a process used to remove dye from

stained fibers, usually involving sodium hydroxide, sodium

hydrosulfite, and a set temperature and time at which the

fabric or fibers are exposed to the clearing (reducing)

solution.

19. Scour: to remove oils, fats, waxes, soluble im­

purities, and any particulate or solid dirt adhering to the

fibers. The process consists essentially of treatment with

a detergent with, or without, the addition of an alkalai

(35:78).

20. Solvent: liquid substance that is capable of dis­

solving or dispersing one or more other substances.

21. Spectral reflectance curve: graphic representation

of the light reflected from a surface under a specific light­

ing condition.

8

22. Sublimation; the ability of a solid to pass

directly from the solid to gaseous state, or vice versa,

without an intervening liquid state.

CHAPTER II

REVIEW OF THE LITERATURE

The review of literature revealed that the proposed

study is a relatively original project and that work in this

area has not been conducted by other researchers. However,

literature pertinent to the determination of fiber content

in polyester/cotton blends was reviewed. The survey of

related literature is presented as follows: (1) Analysis of

Blend Compositions, (2) Fiber Properties, (3) Disperse Dyes,

(4) Thermosol Method, and (5) Colorimetric Measurement.

Analysis of Blend Compositions

The established method for determining polyester/cotton

fiber blend proportions is the procedure outlined in the

AATCC Test Method 20A (2). This gravimetric procedure in­

volves weighing a bone dry sample, dissolving the cellulose

contained in the sample with 70% sulfuric acid and determin­

ing the weight of the bone dry polyester residue. Thus, cal­

culation of the quantities of polyester and cotton is possible

Other methods for determining fiber content in blends of

polyester/cotton fabrics have been reported in the literature.

These methods, like the AATCC test procedure, involve disolu-

tion or hydrolysis of one of the fiber components. King

et al., (21) have advocated the use of hot monoethanolamine

rather than 70% sulfuric acid or hot 5.25% sodium

10

hypochlorite. The advantage stated for monoethanolamine is

that this solvent is less corrosive than either sulfuric

acid or sodium hypochlorite. King and Stanonis (20) have

also reported that tetrachloroethane may be used to dissolve

the polyester component from the blend, thereby determining

the blend configurations. This method involves pretreatment

of the fabric with sodium bicarbonate or sodium acetate.

This pretreatment helps to prevent damage to the cellulose

by the hydrogen chloride which is generated in situ through

reaction of the tetrachloroethane with the moisture which is

present in the cotton.

In later work (19) these same authors demonstrated that

hexafluoroisopropanol dissolves the polyester out of the blend

with a reduced amount of damage to the cotton portion of the

fabric. With this method, as with the tetrachloroethane,

treatment with sodium bicarbonate or sodium acetate is

recommended.

Rueckert (30) has reported the use of trichloroacetic

acid to dissolve polyester in blends with cotton, wool or

flax. Preliminary testing has shown that the solvent appears

to have no detrimental effect on rayon, acrylic, polyethylene

or polypropylene. This method may not be used in blends con­

taining nylon or polyvinyl chloride.

A variation of the dissolution methods has been reported

by Wasserman et al. (36). This microtechnique involves the

11

use of a very high solvent to fiber ratio resulting in rapid

dissolution, filtering and drying. Clark et al., (8) have

adapted this microtechnique to the analysis of multicompo-

nent fiber mixtures in blends. They reported savings in

time and solvents. They found significant discrepancies be­

tween the micro and macroanalytical techniques in 15% of

their test samples.

In conclusion, the established methods for determining

fiber blend levels invariably involves the dissolution of one

of the fiber components and subsequent gravimetric determina­

tion of the remaining fiber.. These procedures often involve

toxic chemicals and lengthy time periods (approximately five

hours) in which to be performed.

Fiber Properties

Cotton

Cotton is a cellulosic fiber containing linear polymers

which are built by combining several thousand anhydroglucose

units. Cellulose is a carbohydrate having the following

chemical composition (18:24):

r

OH

H I C

OH I C

OH H H I

c — 0 I CHjOH

H 1 ^

1 \ (

1

CHjOH 1 c —

' \ OH \ 1

c — 1 H

- 0

\ C

-c 1 OH

repeating unit 2 glucose units

n H 1 1 c -

/ OH

c -1 1

CHj

OH 1 1

- C H

— 0

OH

0

CHjOH I c — 0

•I \ OH H / I I / c — c I I H OH

OH

l_ _l

12

Polyester

Polyester is a polymeric ester. It is produced when an

acid (e.g., terephthalic acid) reacts with an alcohol (e.g.,

ethylene glycol). The following equation illustrates the

chemistry involved in the formation of du Font's Dacron

(28:435) .

nHOOC-^^COOH + nHO(CH2)20H >

H0[-0C-^^-C0.0(CH2) 20-]j^H+ (2n-l)H^0

Disperse Dyes

Early in the development of man-made fibers, it was

realized that new dyes, equipment and procedures v/ould have

to be developed to successfully dye the new fibers. Some

man-made and most of the synthetic fibers were shown to be

hydrophobic (11:273), with closely packed molecular chains

(14:18). These two factors led to difficulties when dyeing

was attempted with conventional water-soluble dyes. It was

found that the disperse dyes, developed in 192 3 for the dye­

ing of cellulose acetate, could be successfully applied to

polyester fibers. Disperse dyes were first known as acetate

dyes, then dispersed acetate dyes, dispersion dyes and dis-

persol dyes. The presently accepted name, disperse dyes was

introduced in 1951, and accepted by the Society of Dyers and

Colourists in 1953 (32:2479). The definition of disperse

dyes according to the Society of Dyers and Colourists (32:

13

2479) is "Substantially water insoluble dyes having sub-

stantivity for one or more hydrophobic fibers, for example,

cellulose acetate and usually applied from fine aqueous

dispersion."

Cotton is a relatively porous fiber. It is normally

dyed with large, water soluble dyes which have a direct

affinity for the hydrophilic fiber. Polyester, on the other

hand, is a hydrophobic fiber usually having no reactive

groups. It is best dyed with essentially water insoluble,

disperse dyes which are molecularly relatively small in rela­

tion to other dye classes. Because of the physical and chem­

ical structure of cotton fibers, the molecularly small

disperse dyes can easily enter as well as leave the fiber.

It is for this reason that cotton is only stained by disperse

dyes.

Thermosol Method

Research conducted by scientists of the du Pont de

Nemours Company, found that dry heat alone would sublime a

film of disperse dye into most synthetic fibers. Joseph

Gibson (13:19) conducted research during the late 1940's

that led to the development of the Thermosol method. In

principle, the Thermosol method is very simple; it can be a

continuous dyeing procedure that involves padding the fabric

with a dye dispersion, then drying at 100°C to reduce migra­

tion of the dye and finally, subliming the dye film into the

14

fibers at temperatures of 175-225°C for 5-90 seconds.

According to Gorondy (14:19) the Thermosol method is the

only practical, continuous dyeing process for the dyeing

of polyester fibers.

The ability of a dye to sublime, or pass directly from

the solid to gaseous state, is dependent upon the size of

the dye aggregates. The fewer the number of dye molecules

that are grouped together, the smaller the aggregate and the

more readily the dye will sublime. Commercially available

disperse dyes are finely ground powders that are capable of

being suspended in a state of dispersion. Because they are

so finely ground the dispersion has few coarse particles and

many fine, minute dye particles. This physical structure of

the dye dispersion allows disperse dyes to volatilize easily

and so suits them for the Thermosol process.

Balchin (3:13) has postulated that the heat of the

Thermosol method opens the polymer structure and makes the

fiber more permeable to the dye, which diffuses from the

surface into the interior of the fiber. Dye fixation is

dependent upon the molecular size, shape, solubility and

volatility of the dye in the fiber.

The Thermosol method is well suited for dyeing the

polyester portion of polyester/cotton blends. When the

fabric is padded with the dye dispersion, dyestuff is de­

posited upon both fibers. Brent et al. (6:606) showed that

15

during the Thermosol phase of the dyeing procedure, some of

the dye deposited on the cotton portion of the blend trans­

fers to the polyester portions of the blend. They concluded

that this movement of dye from one fiber to the other

occurred by vapor transfer rather than contact migration.

Most dye stain remaining on the cotton fibers may be removed

by a reduction/clear treatment.

Commercially, the growth of the Thermosol method

parallels that of polyester/cotton blends. By the late

1970's there were approximately one billion pounds of fiber,

mostly in polyester/cotton blends, annually being dyed by

the Thermosol process in the United States (13:22).

Colorimetric Measurement

Color Perception

The perception of color is dependent upon three separate

factors; an observer, an object, and light. The human per­

ception of color is both a physical and psychological re­

sponse. The eyes are the receptor, an object is the stimulus

and a lighting source is the illuminant.

Light rays are a part of the spectrum of electromagnetic

energy. Light rays are measured by the distance from wave

crest to wave crest using nanometers (one nm is equal to one-

billionth of a meter). Visible light rays compose a narrow

part of the total energy spectrum falling between 380 to

16

720 nm. The following colors are associated with the indi­

cated wavelength ranges:

Blue, Violet 380-480 nm Green 480-560 nm Yellow 560-590 nm Orange 590-630 nm

Red 630-720 nm

Color is perceived when light from the visible spectrum

strikes the eye directly, or when an object reflects part of

the light spectrum back into the line of vision (9:173).

The receptors in the eye which are responsible for color

vision are the cones. When a stimulus hits the eye, it

excites the three types of cones present on the retina (in­

terior lining of the eye) differently. These three types of

cones have different sensitivity to red, blue, and green.

The different responses by the cones to the color stimulus

are transmitted to the brain where they are mixed and color

is perceived (23:24).

Without light or a source of illumination, color cannot

be seen. White light, such as sunlight, incandescent light,

and fluorescent light, contains the whole spectrum of visible

light. Sir Isaac Newton demonstrated this in 1730 when he

separated white light into color bands by causing it to pass

through a prism.

Color Systems

For color to be discussed, reproduced and documented,

a need was recognized for an orderly arrangement of colors.

17

In the early part of this century. Professor Wilhelm Ostwald

devised a triangle based on a color wheel of six colors.

This system defines colors by their color content, white and

black content in terms of idealized spectrophotometric curves

(5:30). In the 1920's, Munsell expanded the Ostwald system

by accommodating brighter colors than had previously been

possible (23).

The Munsell system defines color using three descrip­

tive terms; hue, value and chroma. Hue is the color family,

for instance, red, blue or green. Value is a description

of the amount of white or black a color contains, and chroma

is used to describe the saturation or purity of a color.

The Commission Internationale de I'Eclairage (CIE,

International Commission on Illumination) developed a color

system to be used in color measurement. Where the Ostwald

and Munsell color systems are based on physical samples,

(i.e., paint chips), the CIE system is based on mixing

colored lights.

The mixture of colored lights is known as additive

color mixture. With the addition of three primary colors;

red, blue, and green, secondary colors are achieved and

finally white is produced.

To report color data in the CIE system, the CIE X, Y,

and Z tristimulus values are used to determine chromaticity

coordinates x, y, and z. The CIE X, Y, and Z tristimulus

18

values are imaginary red, green and blue primary lights

chosen for color description. The use of these imaginary

primary lights circumvents the problem of negative numbers

that would occur if actual primary lights were used (5:38).

Only two of the chromaticity coordinates (x, y, or z)

are needed to plot a planar point on a chromaticity diagram

(since x + y + z = 1) which is capable of yielding dominant

wavelength and percent purity. The tristimulus value Y is

used to indicate luminosity, or the lightness of a color

(5:38), in addition to the quantity of green.

Colorimetry

A very broad definition of colorimetry (9:185) is "the

scientific measurement of color usually based on reflected

light." Colorimeters usually determine the proportions of

the primary additive lights which are necessary to match the

color reflected or transmitted by the sample under investiga­

tion (35:668). In its simplest form, a colorimeter may con­

sist of a viewing tube with half the viewing field being

illuminated by light reflected from the test specimen; the

other half being directly illuminated by a beam of standard

light. The beam of standard light is altered by the inser­

tion of primary colored glass filters, until a color match

is obtained. With the use of calibrated controls and trans­

formation equations, the CIE X, Y, and Z tristimulus values

may be determined (34:668).

19

Sample Preparation

Colorimeters are extremely sensitive to the way in

which a sample is displayed to the viewing eye. There are

many factors related to the sample, or sample preparation

which may influence the colorimetric reading.

Saltzman (33:130) has stated "We have instruments that

are far better than the samples we prepare for measurement."

Problems which cause inaccurate readings and which are asso­

ciated with sample preparation include soiled samples giving

inaccurate readings, unlevel dyeings in the samples, im­

proper mounting of the sample (allowing background to show

e.g., translucent samples and samples that are not flat in

the holder) and improper conditioning of the sample. Sur­

face gloss, polarization and/or fluorescence also interfer

with correct measurement. According to Hoban (15:17) the

surface of the textile sample may cause problems when trying

to obtain an accurate reading. Highly textured fabrics such

as corduroy, twills, wide wale knits and sculptured carpets

will yield different measurements depending upon the sample

orientation in the instrument. If the pile of a fabric is

especially long as in some carpet samples, velours, and

velvets, then mounting the sample behind glass to keep the

pile from extending too far into the instrument may be neces­

sary. If glass is used, then a correction factor must be

20

included into the color matching formula to account for the

effect of the glass on the readings. Suchecki (33:130) has

drawn attention to the fact that any change in the substrate

to which a dye is applied will affect the colorimetric read­

ing. Any difference in the fiber content, denier or fiber

shape, fabric construction, or addition of finishing agents

can cause variations in dye acceptance.

Color Difference

A single number has long been sought which could give

accurate, repeatable and consistent information on the am.ount

or quantity of color difference between a sample and standard,

There are many calculations available to determine color dif­

ference or AE. Unfortunately, the results of many of these

calculations are not the same, nor do they correspond with

subjectively assessed color differences. Two of the histor­

ically more important color difference calculations were due

to Nickerson in 1936 (29) and Balinkin in 1941 (4) who devel­

oped formulas based upon the Munsell Color System. The

National Bureau of Standards (NBS) developed a color differ­

ence formula based on the uniform chromaticity scale of

Hunter (16). The American Society of Testing and Materials

(ASTM) has used the 194 2 Adams formula (1). The MacAdam

color space (27) was used as a basis for the revisions by

Davidson in 1956 (10), and Simon in 1958 (31). The most

recent recommendations for a color difference equation by

21

the American Association of Textile Chemists and Colorists

is the CIE 1976 L* a* b* formula (2:122-123).

Kubelka-Munk Analysis

The Kubelka-Munk equation for color computation is

based upon the relationship of reflectivity and colorant

concentration,

K/S [dye],^j^^^_

The Kubelka-Munk equation is:

K/S = (1-R) /2R

where:

K = sum of dyestuff and fiber absorption

S = scattering or changes in the direction of light rays

R = reflectance or light scattered back from opaque material

For dyeing of textiles, it is assumed that all scatter­

ing occurs by the substrate, not by the colorant. The

Kubelka-Munk theory makes the following assumption: there

is diffuse illumination and viewing without polarization of

light; there is a plane, parallel surface with no light loss

at the edges; there is no allowance for the presence of

large particles, agglomeration or orientation of the par­

ticles in the layer; there is optical contact with the next

layer; and finally, the scattering particles are large in

comparison to the wavelength, but small compared to the

fabric thickness (22:14-15).

CHAPTER III

PROCEDURE

The purpose of this study was to develop a rapid and

accurate methodology for determining polyester fiber content

in polyester/cotton blends. it was hypothesized that there

would be a significant difference between the Thermosol

techniques and the AATCC Test Method 20A for determining

polyester content, and that significant differences would be

found between the polyester contents of desized, and scoured

and bleached fabrics as determined by the Thermosol tech­

niques. This chapter outlines the methodology developed for

this study. It also includes detailed descriptions of the

experimental design.

Pilot Study

A pilot study was conducted before initiation of the

actual research. The objectives of the pilot study were as

follows:

1.- To determine if there was a color difference between

varying polyester and cotton fabric blend levels when these

fabrics were dyed with the Thermosol method using disperse

dyes.

2. To develop a methodology for the dyeing and reduc­

tion/clear procedures to be used in the study.

3. To determine if the research project would be fea­

sible in terms of available time and equipment. 22

23

During the pilot study, it was found that there was

indeed a color difference between polyester/cotton blend

fabrics of various fiber blends which had been dyed using

the same disperse dye at the 2% w/w depth of shade. It

was determined during the pilot study that all fabrics

required a reduction/clear stripping before colorimetric

measurement of the samples in order to insure consistent

data acquisition. Familiarity with the equipment and

methods was also gained by the author during the pilot study.

Because the pilot study was successful in terms of the objec­

tives mentioned above, it was recommended that the study

proceed.

Major Study

Experimental Design

After the pilot study was complete, the overall exper­

imental design of the main study was outlined. It was recom­

mended that the actual fiber contents of the fabric samples

be determined by AATCC Test Method 20A. The sublimation

techniques on both fabrics and fibers would be tested using

two heat sources: a Benz Laboratory Drying and Curing Appa­

ratus and a regular household iron. It was also decided that

both bleached and desized fabrics be used to determine

if the polyester content could be determined with acceptable

accuracy using fabric in either state. Finally, it was

determined that the testing should be conducted using

24

at least two different disperse dyes (see Figure 1 for spe­

cifics of the experimental design).

Selection of Fabric Samples

Five of the six fabrics used were produced specifically

for this project by the Textile Research Center (TRC), Texas

Tech University. The sixth fabric was donated by the Postex

Plant of Burlington Domestics (Division of Burlington Indus­

tries, Inc.) Post, Texas. The fabrics were available orig­

inally as greige goods and were all plain weave construction

being composed of polyester and cotton. The fabric blend

donated by Burlington had no specific fiber type or construc­

tion information supplied with the sample (see Tables 1, 2,

3, and 4 for specific fiber and fabric properties).

Determination > Proportions in using Dissolut

of Bl ion

Fiber ends Analyses

To determine actual blend level compositions, all de-

sized fabric blend samples were analyzed using the AATCC

Test Method 20A (2:46-51) as well as a polyester dissolution

method (21).

Procedure for AATCC Test Method 20A. A bone dry sample

(1.0 g) was accurately weighed to the nearest 0.005 g. It

was transferred to a beaker (250 ml) and 70% sulfuric acid

(100 ml) was added. The sample was agitated for 32 minutes

then filtered through a fritted-glass crucible which had

25

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TABLE 1

FABRIC CONSTRUCTION PROPERTIES (Of P o l y e s t e r / C o t t o n B l e n d F a b r i c s u s e d i n t h i s S t u d y )

Physical Properties

Yarn Sizes Ends Per Inch Picks Per Inch Fabric Weights (oz/yd )

Desized Fabrics Nominal % Polyester

100

35/1 82.0 76.0 3.45

65

69.0 58.0 3.65

60

35/1 82.0 81.0 3.50

50 .

35/1 82.2 81.0 3.58

40

35/1 82.0 80.8 3.40

0

35/1 85.2 80.8 3.60

Bleached Fabr ics Nominal % Po lyes t e r

Yarn Sizes Ends Per Inch Picks Per Inch Fabric Weights

2 (oz/yd )

35/1 82.8 62.4 3.15

—

—

—

——

35/1 88.0 72.6 3.30

35/1 88.8 74.0 3.30

35/1 86.4 73.8 3.30

35/1 92.0 73.8 3.29

TABLE 2

POLYESTER CONTENT* (Of P o l y e s t e r / C o t t o n B l e n d F a b r i c s u s e d i n t h i s S t u d y )

Nominal Po lye s t e r

100 65 60 50 40 0

Actual % Polyester

99.9 65.3 63.6 50.1 45.1 0.0

*As determined by the AATCC Test Method 20A (2)

27

TABLE 3

COTTON FIBER PROPERTIES

Type Acala S tap le Length (inches) 1 . 16 Uniformity Ratio 46 Short F ibe r s ( < l / 2 " ; %) 2.90 S t reng th (0 Gauge P r e s s l e y ; m ps i ) 98.13 Elongat ion (%) 4.83 Non- l i n t Content (%) 6.7

TABLE 4

POLYESTER FIBER PROPERTIES

Type Hoechst 421 S tap le Length ( inches) 1.5 Weight/Unit Length (denier) 1.5

28

been oven-dried, desiccator cooled and tared to the nearest

0.005 g. Suction was applied and 3 aliquots (10 ml each) of

70% sulfuric acid were passed through the sample. The

crucible was washed with sulfuric acid (50 ml, water:acid =

1:19), then with distilled water until the filtrate was

neutral to litmus. The suction was disconnected and ammonium

hydroxide (25 ml, water:acid = 8:92) was added to the cruci­

ble, and allowed to soak for 10 minutes. The suction was

again applied to the residue which was then rinsed with dis­

tilled water (150 md). The crucible and oven-dried (105°C

for 2 hr) residue were cooled in a desiccator for 30 minutes

and the weight of the dry residue was recorded to the near­

est 0.005 g. The polyester percentage was then calculated

as follows:

Percent Polyester = Final Dry Weight ^

•^ Initial Dry Weight

Tetracholorethane Dissolution Analysis. A bone dry

fabric sample (1.0 g) was accurately weighed to the nearest

0.005 g. The sample was soaked in a solution of sodium bi­

carbonate (8%), pressed between filter paper and oven-dried

(30 minutes at 105°C). The sample was then immersed in

tetrachloroethane (20 ml) and heated from room temperature

to the reflux temperature (150°C) of the solvent. The mix­

ture was rapidly cooled to room temperature in an ice bath.

The fabric sample was transferred to fresh tetrachloroethane

(20 ml) and the heating/cooling process repeated twice. The

29

remaining cotton was rinsed 3 times with ethyl alcohol, then

with distilled water. The sample was oven-dried (2 hr at

105°C) cooled in a desiccator for 30 minutes and the weight

was recorded to the nearest 0.005 g. The cotton percentage

was then calculated as follows:

Percent Cotton = Final Dry Weight Initial Dry Weight

Fabric Preparation

The following steps were taken in preparing the samples

for testing:

1. Removal of Sizing. The warp yarns of the TRC fabric

samples had been sized with polyvinyl alcohol. To remove

this sizing, the following procedure was followed on a lab­

oratory, small scale basis. Fabric samples (1 yd each) were

wetted out in a paddle machine (9 0 1 capacity). The water

temperature was raised to 96°C and the surfactant, Strodex

Super V-8 (Dexter Chemical Corporation; 10 g for each yard

of fabric) was added. The water temperature was maintained

for 1 hour during which time the fabric was continuously

agitated. The fabric was then rinsed thoroughly, extracted,

and tumble-dried.

The warp yarns of the Postex Plant fabric sample had

been sized with starch. The sample was desized with an

enzyme-containing mixture as follows: the fabric (262 g)

was wetted out in a paddle machine (90 1 capacity). The

30

water temperature was raised to 75°C and stabilized at this

temperature. Rapidase XC (GB Fermentation Industries, 25.5%

owf), sodium chloride (17% owf), and Triton XlOO (Rohm and

Haas, 1.7% owf) were added. The fabric was agitated con­

stantly for 30 minutes, rinsed, extracted and tumble-dried.

2. Desizing, Scouring and Bleaching. In a separate

procedure, fabrics from the TRC were desized, scoured and

bleached (with the exception of the 100% polyester sample

which was desized only) on a full scale industrial basis.

The procedure for the desizing of the fabrics was as follows:

The fabrics (complete with end cloths) were loaded into a

jig. The jig was partially filled with water (300 1), and

hydrogen peroxide (1.5% owf, 35%) acetic acid (0.5% owf),

and Triton XlOO (0.1% owf) were added. The liquor tempera­

ture was raised to 96°C and maintained for 1 hour. The

fabric was then rinsed twice with cold water. For scouring,

the jig was again filled with cold water to yield a liquor:

goods ratio of 10:1 and then caustic soda (see Table 5 for

specifics) was added. The liquor temperature was raised to

96°C and maintained for 30 minutes. The fabrics were rinsed

with cold and then boiling water. For bleaching, the jig

was again filled to produce a liquor:goods ratio of 10:1 and

hydrogen peroxide, sodium silicate, sodium carbonate and

sodium hydroxide were added. The liquor temperature was

raised to 96°C and maintained for 30 minutes. After draining

31

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32

the spent bleach liquor, the fabrics were rinsed twice with

cold water, then again with boiling water, neutralized with

acetic acid (50 ml), and finally rinsed with cold water

prior to drying at 110°C.

3. Fabric Sample Size. The prepared fabric samples

were cut into samples (3.5 + 0.1 g), and numbered for iden­

tification with an indelible marker.

Fiber Preparation

Samples (5.0 + 0.1 g each) were prepared for testing

in the following manner:

1. Gravimetric Measurement. Mixtures of polyester and

cotton fibers were weighed out into samples (5.0 g each).

Each sample was representative of a polyester/cotton blend

proportion (90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70,

20/80, 10/90).

2. Blending. The samples were hand blended to dis­

tribute the fibers.

3. Package Preparation. Each sample was stitched into

a gauze package (Johnson and Johnson Gauze Sponge 4 X 4 - 16

ply, U.S.P. Type VII gauze) and marked for identification

with an indelible marker on a one-inch square of muslin sewn

into the end of the gauze package.

Preparation of Dye Dispersion

The disperse dyes chosen for this study were: Color

Index (CI) Disperse Blue 73, an anthraquinone, medium energy

33

dye and CI Disperse Red 122, an azo, medium to high energy

disperse dye. They were dispersed in the following manner.

The disperse dye powder was weighed accurately (20 +

.005 g) and then pasted with distilled water. To this paste

were added Superclear N 100, an antimigrant (Diamond Sham­

rock Industries, 20 g), Strodex Super V-8 (10 ml of a 10%

solution), and enough water to produce a total weight of

one kilogram. This mixture was then converted into a disper­

sion by blending it for 3 minutes using a Thermolyn Magnetic

Stirrer (Model #SP-A1025B). In this way a 2% weight per

weight (w/w) dispersion was produced. Dispersions containing

1% and 3% w/w of dye were produced in a similar manner.

Thermosol Method

Benz Procedure

The Benz Laboratory Drying, Curing and Setting Apparatus

(Benz) Unit (see Figures 2a and 2b) was used to develop a

standard method of Thermosoling. Six Thermosol techniques

were identified and tested using the Benz. Throughout the

study they will be referred to as follows:

Technique 1- Disperse Blue (2% w/w), Benz/Desized Fabric Technique 2- Disperse Blue (1% w/w), Benz/Desized Fabric Technique 3- Disperse Blue (3% w/w), Benz/Desized Fabric Technique 4- Disperse Red (2% w/w), Benz/Desized Fabric Technique 5- Disperse Blue (2% w/w), Benz/Fiber Technique 6- Disperse Blue (2% w/w), Benz/Bleached Fabric

34

FIGURE 2a

THE BENZ UNIT

Dye Pad 90-100% p . u .

Dry o

90 C Thermosol

200°C

FIGURE 2b

SCHEMATIC DRAWING OF BENZ UNIT

35

The following steps were used to dye each fabric sample for

the sublimation techniques listed on page 33.

1. The oven temperature thermostat was set for drying

(90°C).

2. The pad roller air pressure was set (8 psi) to pro­

duce a wet pickup of dye dispersion in the range of 90 to

100%.

3. The fabric samples were dipped into the dye dis­

persion, passed through the pad rollers and then weighed to

determine the percent wet pickup.

4. The padded fabrics were placed on the Benz frame

and held taut between the parallel rows of metal pins.

5. The impregnated fabric samples were dried at 90°C

for 2 minutes using a speed of 1.6 yards per minute.

6. The Benz heating unit was then equilibrated at 200°C

7. Dyeing was achieved by passing the dry fabrics

through the Benz Unit at 2 00°C for 2 minutes.

8. The samples were removed from the frame and sub­

jected to a reduction/clear stripping process.

For dyeing fiber samples in the Benz, steps 1 through

8 were followed as for the fabric samples. The exception to

this was that in step number 5, the speed of passage was

reduced (5 minutes, 0.8 yards per minute) to insure that the

mass of fibers dried thoroughly.

36

Reduction/Clear. A solution of sodium hydrosulfite and

sodium hydroxide (1% w/w with respect to each) was prepared

in the following manner: sodium hydrosulfite and sodium

hydroxide (1 + 0.005 g each) were weighed out and dissolved

in distilled water (998 g). The solution was used immedi­

ately before the sodium hydrosulfite had a chance to

decompose.

Fabric Samples. The dyed fabric samples were placed

into the reduction/clear solution (200 g, liquor:goods =

57:1) , and the temperature of the solution was raised to 85°C

and maintained for la minutes. The fabric samples were

stirred during the entire process. The samples were then

rinsed and air dried.

Fiber Samples. The fiber samples were subjected to the

reduction/clear treatment in the same manner as the fabric

samples, with the exception that the fibers were removed

from their gauze packages before stripping and the quantity

of stripping solution was increased to 2 85 g in order to keep

a constant liquor:goods ratio (57:1).

Machine Blending. To obtain the best possible blend,

the stripped fiber samples were processed through a Spinlab

33 8 Fiber Opener/Blender. The fibers were passed through

the blender 5 times, each time the sample was rotated through

45 degrees (with respect to the previous passage) and on the

final pass through the blender, the sample was turned top

37

to bottom. The fibers were then considered to be prepared

for colorimetric measurement.

Iron Procedure

Two iron sublimation techniques were identified and

tested. They will be referred to throughout the study by

their respective technique number. They are as follows:

Technique 7- Disperse Blue (2% w/w), Iron/Desized Fabric Technique 8- Disperse Blue (2% w/w), Iron/Fiber

These iron sublimation techniques used a household iron (Gen­

eral Electric Self Clean II, 1100 watts) to sublime the dye

into the fibers. The iron was equilibrated to heat the

sample, sandwiched between aluminum foil, to a range of 199-

204°C as verified by heat sensitive paper. The following

procedure was followed:

Fabric Samples. The desized fabric samples were handled

in the following manner.

1. The samples were padded through the dye dispersion

in the same manner as were the samples dyed with the Benz

method.

2. The padded samples were dried in the following man­

ner; they were pinned to one rack of a Stabil-Therm Constant

Temperature Cabinet (Model #DV-500C-2) with wooden, spring-

type clothes pins and positioned in the middle of the oven.

They were dried for 30 minutes at 90°C and removed from the

oven.

38

3. The iron was set at the "cotton" setting on the

heat indicator dial and adjusted so that it would supply dry

heat only, no steam.

4. The fabric sample was placed between two layers of

aluminum foil.

5. The heated iron was placed on the aluminum foil

encased sample for 20 seconds. Constant pressure was sup­

plied by the actual weight of the iron (1 lb, 4 oz) plus the

weight of a lead collar that was fitted to the iron (7 lb,

12 oz).

6. After 20 seconds, the sample was removed from be­

tween the layers of foil and subjected to the same reduction/

clear treatment as described for the Benz method samples.

Fiber Samples. The fiber samples were handled in the

following manner.

1. The samples were padded with dye dispersion in the

same manner as were the Benz method samples.

2. The padded fiber samples were dried in the same

manner as the fabric samples.

3. The iron was set at the "cotton" setting and

adjusted so that it would supply steam.

4. The fiber samples were blended in the same manner

as the Benz fiber samples. The blended samples were weighed

out (1 + 0.1 g) and spread into a thin mat on aluminum foil.

39

5. The heated iron was placed directly onto the fiber

sample for 20 seconds with the same pressure as was used on

the fabric samples. After 20 seconds, the sample was turned

over and the heating process repeated.

6. The fiber samples were subjected to the same reduc­

tion/clear treatment (liquor:goods ratio = 57:1) as the

fabric samples.

Colorimetric Measurement

All colorimetric measurements were performed on a

Macbeth 1500 Color Measurement System. The following steps

were followed in making each measurement:

1. The instrument was calibrated with a standard white

tile using CIE illuminant C and a 2° viewing angle.

2. The samples were exposed to the viewing eye of the

instrument in accordance with the manufacturer's recommenda­

tions.

3. Reflectance measurements were made three times on

each sample. Subsequently, the average of these three read­

ings was recorded.

4. Data recorded for each sample included L* a* b*,

AE wavelength of minimum reflection, and the reflectance at

this wavelength.

40

AE was determined using the following CIE 19 76 L*

a* b* formula:

^^CIELAB = t(^L*)2 + (Aa*)2 + (Ab*)-]^/^

where

L* = 24 (lOOy/y )^^^ - 16

a* = 500 [(X/X )-^/^ - (Y/Y )-^^^]

h* = 200 [(Y/Y )-^/^ - (Z/Z )-'-/]

When X , Y , Z , are the tristimulus values of the o o o

nominally white standard, Y becomes equal to 100.

5. The Kubelka-Munk K/S values were then calculated

for each sample using the following equation:

K/S = (1 - R)^/2R

CHAPTER IV

ANALYSIS OF DATA

The primary objective of the study was to develop a

rapid method for the determination of polyester fiber blend

levels in polyester and cotton blends. The study consisted

of developing a methodology for the procedure using a Benz

Unit, then applying the same methodology using a household

iron.

The results of the Thermosol method were compared to

those results determined by the AATCC Test Method 20A.

Eight sublimation techniques were developed and subsequently

tested on polyester and cotton blends. Figure 3 is a graphic

overview of all the fiber determination techniques used in

this study.

Fiber Blend Analyses-Dissolution Test Results

AATCC Test Method 20A

The average polyester contents of a polyester, a cotton,

and four polyester/cotton blend fabrics as determined by the

AATCC Test Method 20A are summarized in Table 6. The data

reported are the means of twelve determinations for each

blend level group. The standard deviations indicate that

the accuracy of the test decreases as the polyester content

of the fabrics decreases.

41

4 2

^

Polyester /Cotton Blend SZ

Desized FaUaric

Sulfuric Acid Analysis

Tetrachloro­ethane Analysis

1 Desized Fedbric

Disperse Blue 2% w/w (5)

Benz Sublimation Technique

Disperse Blue ?.% w/w (8)

< 1 -Iron Sublimation Technique

Fiber Samples

r^

Fabric Samples

Benz Sublimation Technique

Bleached FeUaric .

Disperse Blue

Desized Fedsric T£>

Disperse Blue

Iron Sublijnation Technique

--0>

Disperse Red 2% w/w (4)

Disperse Blue 2% w/w (7)

r> 2%. w/w ( 6 , 1 )

1% w/w

(2)

3% w/w

(3)

FIGURE 3

METHODS OF FIBER CONTENT DETERMINATION

43

TABLE 6

FIBER ANALYSIS (AATCC T e s t Me thod 20A)

Sample Number

P o l y e s t e r Conten t (%)

Nominal

100

65

60

50

Polyester Content (%) Actual

99.9

66.6 65.6 66.1 66.2 65.5 64.8 64.8 64.8 65.2 65.0 64.8 64.5

65. 64. 64. 64. 63. 63. 63. 63. 62. 63. 63. 63.

51. 52 50 50 50 49 49 49 49 49 49 50

1 6 5 3 0 1 3 2 9 2 1 4

.0

.2

.1

.6

.4

.4

.6

.4

.4

.2

.5

.0

Actual Mean

Actual Standard Deviation

65.3 0.67

63.6 0.75

50.1 0.87

44

TABLE 6 — C o n t i n u e d

Sample Number

5

6

Polyester Content (%) Nominal

40

0

Polyester Content (%) Actual

49.0 46.7 46.7 45.9 44.1 43.9 44.1 44.2 44.1 44.1 44.6 44.0

0 .0

Actual Mean

45.1

Actual Standard Deviation

1.51

45

Tetrachloroethane Method

The average polyester contents of a polyester, a cotton,

and four polyester/cotton blend fabrics as determined by the

tetrachloroethane dissolution method are summarized in Table

7. The data reported are the means of three determinations

on fabric samples for each blend level. Comparison of the

standard deviations indicates that the tetrachloroethane pro­

cedure is a more accurate test method than the sulfuric

acid dissolution technique for determining polyester content

in polyester/cotton blends. All standard deviations for the

tetrachloroethane test are lower than those standard devia­

tions derived from the currently accepted AATCC Test Method,

despite the fact that fewer samples were tested using the

organic solvent technique.

Fiber Blend Analyses-Colorimetric Measurement

The data for all colorimetric measurements performed on

both cotton and polyester fabrics and polyester and cotton

fiber blend samples are shown in Tables 17 through 24 (Appen­

dix B) . The data presented in these tables includes the

nominal and actual polyester contents, AE and K/S data as

well as the standard deviations for both AE and K/S.

From the raw data, simple linear regression equations

were generated to allow prediction of polyester content.

This latter information is presented in Tables 8 and 9.

TABLE 7

FIBER ANALYSIS (Tetrachloroethane Method)

46

Sample Number

1

2

3

4

5

6

Polyester Content (%) Nominal

100

65

60

50

40

0

Polyester Content (%) Actual

DC* DC DC

65.3 65.5 65.4

62.7 62.7 62.8

48.8 48.5 48.8

43.6 43.6 43.9

0.0 0.0 0.0

Actual Mean

65.5

62.7

48.7

43.7

Actual Standard Deviation

0.10

0.05

0.19

0.13

DC- Dissolved Completely.

TABLE 3

47

SIMPLE LINEAR REGRESSION EQUATIONS (y = ax + b)

(y = P o l y e s t e r C o n t e n t , x = AE)

Technique

1

2

3

4

5

6

7

8

9*

Regression Equation

Slope (a)

2.0904

2.2674

2.3132

2.6614

2.8971

2.5683

2.0221

2.3678

0.9843

Intercept (b)

-54.2268

-54.3757

-68.9171

-84.8770

-94.1716

-75.3981

-49.6458

-69.0264

0.8793

Coefficient of Determination (r^)

0.9744

0.9598

0.9707

0.9481

0.9990

0.9966

0.9405

0.9199

0.9876

standard Error y on x

1.9418

2.5489

2.0757

2.7621

0.9187

0.7913

2.9587

3.8292

0.9824

Technicjue Technique Technique Technique Technique Technique Technique Technicjue Technicjue

1-Disperse Blue 2-Disperse Blue 3-Disperse Blue 4-Disperse Red 5-Disperse Blue 6-Disperse Blue 7-Disperse Blue 8-Disperse Blue 9-AATCC Test Method 20A/Desized Fabr ic

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) ,

Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Fiber Benz/Bleached Fabric Iron/Desized Fabric Iron/Fiber

*y = i n d i v i d u a l measurement of blend l e v e l X = a c t u a l mean of blend l e v e l measurements

48

TABLE 9

SIMPLE LINEAR REGRESSION EQUATIONS (y = ax + b)

(y = Polyester Content, x = K/S)

Technique

1

2

3

4

5

6

7

8

9*

Regression Equation

Slope (a)

10.7385

13.1407

10.6516

16.0207

13.5695

14.7866

19.4711

12.4579

0.9843

Intercept (b)

23.1384

21.0225

21.9046

16.1786

7.2770

16.1088

24.5346

15.4252

0.8793

Coefficient of Determination (r^)

0.9688

0.9538

0.9775

0.9151

0.9433

0.9912

0.9209

0.9553

0.9876

standard Error y on x

2.1558

1.9442

1.8212

2.6349

6.2631

0.7841

2.5185

2.8629

0.9824

Technique 1-Technique 2-Technique 3-Technique 4-Technique 5-Technique 6-Technique 7-Technique 8-Technique 9-

Disperse Disperse Disperse Disperse Disperse Disperse Disperse Disperse

Blue Blue Blue Red Blue Blue Blue Blue

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) w/w) w/w) w/w) w/w) w/w) w/w) w/w)

Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Fiber Benz/Bleached Fabric Iron/Desized Fabric Iron/Fiber

AATCC Test Method 20A/Desized Fabric

*y = individual measurement of blend level X = actual mean of blend level measurements

49

Simple Linear Regression Analysis-AE Data

The best fit of the equation y = ax + b in Table 8 is

Technique 5. The next best fit for the equation y = ax + b

is Technique 6. Both of the above coefficients of determi-

, 2, 2

nation (r ) are greater than the r value determined for the

AATCC Test Method. The remaining coefficients of determina­

tion for the equations which predict polyester content using 2 2

AE reflectance data range from r =-.92tor =0.97. 2

These high values of r indicate that between 92% and 97% of

the variation in predicted polyester content can be explained

in terms of reflectance. The remaining variation could be

due to experimental error.

Simple Linear Regression Analysis-K/S Data

In Table 9 the best fit of the equation y = ax + b is

seen to be sublimation Technique 6. This method also showed

the least standard error of any of the blend determination

techniques, even that of the AATCC Test Method. The second

best fit of the equation y = ax + b is the coefficient of

determination for sublimation of Technique 3. The remaining

coefficients of determination of the equations for predicting 2

polyester content with K/S reflectance data range from r =

2 0.92 - 0.96. Again, these high values of r indicate

that between 92% to 96% of the variation in predicted poly­

ester content can be explained in terms of K/S data. It is

50

possible that the remaining variation could be caused by

experimental technique.

Confidence Limits for Predicting Polyester Content

The simple linear regression equations shown in Tables

8 and 9 were applied to predict polyester content using both

AE and K/S data. The results of these predictions are shown

in Tables 10 and 11. These tables present the averages of

the predicted polyester content at each blend level for each

sublimation technique. Standard deviations, confidence

limits for the predicted means as well as standard errors of

the means are also shown in Tables 10 and 11.

Table 10 shows that the standard errors of the means

fall with the + limits prescribed by the Federal Trade Com­

mission for acceptable error in labeling, with the exception

of Technique 5. Table 11 illustrates that when K/S data

are used to predict polyester content, all standard errors

of the mean fall within the +_ 3% limits prescribed by the

FTC.

Coefficients of Variation

Coefficients of variation (CV) were calculated for all

blend determination techniques. The CV is a percent of the

sample average, it allows for any discrepancies between

sample sizes for each method. The CV's allow a direct

51

TABLE 10

CONFIDENCE LIMITS OF SUBLir4ATI0N TECHNIQUES FOR DETERiMINING POLYESTER CONTENT IN

POLYESTER/COTTON BLENDS BY AE

Sample Number

1

2

3

4

5

N*

12 12 12 12

12 12 12 12

12 1] 12 12

12 12 12 12

__

^_

_...

_ ^

.«._

- v ^

^ ^

—

Polyester Content

%

AATCC

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0

N*

6 6 6 6

6 6 6 6

6 6 6 6

6 6 6 6

6 6 6 6 6 6 6 6 6

a of Predicted Polyester Content (%) by AE

0.52 0.64 1.29 0.89

1.02 0.53 0.89 1.95

0.54 0.98 0.51 0.58

1.60 1.74 0.57 0.84

1.32 1.05 3.49 2.79 4.51 2.68 1.40 1.23 2.74

95% Confidence Level Polyester Content by AE

Limits for pre­dicted mean

66.3 ± 0.55 61.7 ± 0.67 51.9 ± 1.35 44.5 ± 0.93

66.2 ± 1.07 61.1 ± 0.56 52.1 ± 0.93 44.5 ± 2.04

65.6 ± 0.57 61.9 ± 1.03 52.2 ± 0.54 44.0 ± 0.61

65.1 ± 1.68 62.0 ± 1.83 53.3 ± 0.66 43.6 ± 0.88

88.8 ± 1.39 79.8 ± 1.10 70.4 ± 3.66 60.3 ± 2.92 50.3 ± 4.73 41.5 ± 2.81 28.7 ± 1.47 20.3 ± 1.29 8.90 ± 2.87

standard error of mean

0.21 0.26 0.51 0.36

0.42 0.22 0.36 0.80

0.22 0.40 0.21 0.24

0.65 0.71 0.23 0.34

0.54 0.43 1.42 1.14 1.84 1.09 0.57 0.50 1.19

52

TABLE 1 0 — C o n t i n u e d

Sample Niimber

6

7

8

N*

12 12 12

12 12 12 12

_

—

—

Polyester Content

%

AATCC

63.6 50.1 45.1

65.1 63.6 50.1 45.1

60.0 50.0 40.0

N*

6 6 6

6 6 6 6

6 6 6

aof Predicted Polyester Content (%) by AE

0.92 0.11 1.11

0.88 1.13 0.69 2.68

1.26 1.42 1.93

95% Confidence Level Polyester Content by AE

Limits for pre­dicted mean

63.4 ± 0.96 50.7 ± 0.12 44.7 ± 1.16

65.4 ± 0.92 60.4 ± 1.19 53.4 ± 0.72 43.7 ± 2.81

62.0 ± 1.32 53.2 ± 1.49 43.6 ± 2.03

Standard error of mean

0.37 0.05 0.45

0.36 0.46 0.28 1.09

0.51 0.58 0.79

*N = number of samples

Technique Technique Technique Technique Technique Technique Technique Technicjue

1-Disperse 2-Disperse 3-Disperse 4-Disperse 5-Disperse 6-Disperse 7-Disperse 8-Disperse

Blue Blue Blue Red Blue Blue Blue Blue

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) ,

Benz/Desized Benz/Desized Benz/Desized Benz/Desized Benz/Fiber

Fabric Fabric Fabric Fabric

Benz/Bleached Fabric Iron/Desized Iron/Fiber

Fabric

TABLE 11

CONFIDENCE LIMITS OF SUBLIMATION TECHNIQUES FOR DETERMINING POLYESTER CONTENT IN

POLYESTER/COTTON BLENDS BY K/S

53

Sample Number

1

2

3

4

5

N*

12 12 12 12

12 12 12 12

12 12 12 12

12 12 12 12

___

_.-

^^

_ ^

^^

_ _>

^ ^

—

Polyester Content

(%)

AATCC

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

65.1 63.6 50.1 45.1

90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0

N*

6 6 6 6

6 6 6 6

6 6 6 6

6 6 6 6

6 6 6 6 6 6 6 6 6

a of Predicted Polyester Content (%) by K/S

0.34 0.80 0.61 0.18

0.62 0.49 0.40 0.60

0.76 0.76 0.27 0.50

2.44 1.74 0.44 0.65

3.00 1.77 3.37 2.57 3.63 1.63 0.57 0.65 0.42

95% Confidence Level Polyester Content

Limits for pre­dicted me:an

66.0 ± 0.35 61.2 ± 0.84 51.1 ± 0.64 45.1 ± 0.19

66.9 ± 0.66 60.8 ± 0.51 51.4 ± 0.42 44.9 ± 0.63

66.4 ± 0.80 61.6 ± 0.80 51.1 ± 0.29 44.9 ± 0.52

66.3 ± 2.56 60.6 ± 1.82 52.6 ± 0.46 44.6 ± 0.68

99.7 ± 3.15 80.3 ± 1.86 63.2 ± 3.53 52.3 ± 2.70 42.9 ± 3.80 36.4 ± 1.71 29.8 ± 0.60 24.8 ± 0.68 20.6 ± 0.46

by K/S

Standard error of mean

0.14 0.32 0.24 0.07

0.25 0.20 0.16 0.25

0.31 0.31 0.11 0.20

0.97 0.71 0.18 0.27

1.22 0.72 1.36 1.05 1.48 0.67 0.23 0.27 0.17

54

TABLE 1 1 — C o n t i n u e d

Sample Number

6

7

8

N*

12 12 12

12 12 12 12

_ _

—

Polyester Content

(%)

AATCC

63.6 50.1 45.1

65.1 63.6 50.1 45.1

60-0 50.0 40.0

N*

6 6 6

6 6 6 6

6 6 6

a of Predicted Polyester Content (%) by K/S

1.00 0.21 0.79

1.49 1.62 0.79 1.56

1.74 1.15 1.41

95% Confidence Level Polyester Content

Limits for pre­dicted mean

63.5 ± 1.31 50.2 ± 0.22 45.1 ± 0.83

72.1 ± 1.56 61.1 ± 1.71 47.8 ± 0.83 44.9 ± 1.64

60.2 ± 1.83 49.5 ± 1.21 40.3 ± 1.48

by K/S

Standard error of mean

0.21 0.09 0.32

0.61 0.66 0.32 0.64

0.71 0.50 0.58

N = number of samples

Technique Technique Technicjue Technique Technique Technique Technique Technicjue

1-Disperse 2-Disperse 3-Disperse 4-Disperse 5-Disperse 6-Disperse 7-Disperse 8-Disperse

Blue Blue Blue Red Blue Blue Blue Blue

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) ,

Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Fiber Benz/Bleached Fabric Iron/Desized Fabric Iron/Fiber

55

comparison to be made between the methods in terms of dis­

persion from the mean. Table 12 shows the results of these

comparisons.

Of all the methods used to determine polyester content,

the tetrachloroethane analysis was found to have the lowest

CV's for all the polyester blend fabrics. For the fiber

analysis, the CV's generated from the AE data were consis­

tently lower than those generated by the K/S values.

Determination of Significance

To determine if there were significant differences be­

tween the variables proposed in the following hypotheses,

the t-test for statistical significance was conducted at the

a£.05 level or beyond. The results of these tests are com­

piled and presented in Table 13.

Hypothesis 1. There are significant differences be­tween the Thermosol techniques and the AATCC Test Method 20A in determining the polyester content in desized polyester/cotton blend fabrics.

The first hypothesis was partially accepted. Table 13

shows that there were mixed significance levels within each

Thermosol technique. Overall, the AE data showed greater

nonsignificance than the K/S data. Techniques 1-4 showed

mixed significance for both AE and K/S data when the pre­

dicted polyester content was compared to the polyester con­

tent as determined by the AATCC Test Method. Technique 5

showed no significant difference at thea<_. 05 level between

56

TABLE 12

COEFFICIENTS OF VARIATION (Comparison of AE, K/S, AATCC andTetrachloroethane

Determination of Polyester Techniques)

Sample Number

1

2

3

4

5

Polyester Content

(%)

Nominal

65 60 50 40

65 60 50 40

65 60 50 40

65 60 50 40

90 80 70 60 50 40 30 20 10

Co­efficient of Variation

AE

0.35 0.54 0.99 0.91

0.68 0.44 0.80 1.89

0.40 0.76 0.42 0.43

1.06 1.18 0.42 0.68

0.72 0.63 2.10 1.62 3.13 1.97 1.14 1.06 2.63

Co­efficient of Variation

K/S

0.73 2.26 1.92 0.49

1.43 1.32 1.29 2.20

1.87 2.09 0.71 1.78

5.11 3.97

12.55 2.24

3.37 2.42 6.31 6.02 10.65 8.08 2.41 5.42 5.10

Co­efficient of Variation AATCC

1.03 1.17 1.73 3.34

1.03 1.17 1.73 3.34

1.03 1.17 1.73 3.34

1.03 1.17 1.73 3.34

—

—— —

——— —

1

Co­efficient of Variation Tetrachlor­

oethane

0.15 0.08 0.03 0.30

0.15 0.08 0.03 0.30

0.15 0.08 0.03 0.03

0.15 0.08 0.03 0.30

" * ^ • " • "

^ ^—^

^ •-—^

^

^

57

TABLE 12—Continued

Sample Number

6

7

8

Polyester Content

(%)

Nominal

60 50 40

65 60 50 40

60 50 40

Co­efficient of Variation

AE

0.68 0.14 0.92

0.79 2.68 0.67 2.86

0.97 1.16 1.72

Co­efficient of Variation

K/S

2.50 0.43 A.> • ^ _/

2.24 2.94 1.51 6.73

3.44 3.03 4.82

Cc-efficient of Variation AATCC

1.17 1.73 3.34

1.03 1.17 1.73 3.34

Co­efficient Variation Tetrachlor-

eothane

0.08 0.03 0.30

0.15 0.08 0.03 0.30

Technique Technique Technique Technique Technique Technique Technique Technique

1-Disperse 2-Disperse 3-Disperse 4-Disperse 5-Disperse 6-Disperse 7-Disperse 8-Disperse

Blue Blue Blue Red Blue Blue Blue Blue

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) ,

Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Fiber Benz/Bleached Fabric Iron/Desized Fabric Iron/Fiber

58

TABLE 13

ANALYSIS OF AATCC TEST METHOD AND SUBLIMATION TECHNIQUES

(t-Test for Statistical Significance)

Technique

1

2

3

4

5

6 v.

Nominal Polyester Content (%)

65 60 50 40

65 60 50 40

65 60 50 40

65 60 50 40

90 80 70 60 50 40 30 20 10

60 50 40

df

16 16 16 16

16 16 16 16

16 16 16 16

16 16 16 16

5

5 5 5 5 5 5 5

16 16 16

t AE

-2.93 5.53

-3.75 0.87

-2.17 7.36

-4.58 0.72

0.92 3.92

-5.56 1.66

0.43 2.90 -8.46 2.18

2.13 0.43 -0.33 -7.30 -0.14 -1.34 0.52

-0.62 -0.97

0.64 -1.79 0.56

t K/S

5.56 6.12 -2.55 0

-4.87 8.38

-3.65 0.16

-3.02 5.32

-2.84 0.34

-1.22 5.16

-6.47 0.69

-7.61 -0.43 4.54 4.54 4.60 5.18 -1.12 -17.23 -38.90

0.30 -0.45 0.09

Level of S

AE

S* S S NS**

NS S S NS

NS S S NS

NS S S NS

NS NS NS NS NS NS NS NS NS

NS NS NS

ignificance

K/S

S S S NS

S S S NS

S S S NS

NS

S S NS

S NS S S S s NS S S

NS

NS NS

TABLE 13—Continued

59

Technique

7

8

Nominal Polyester Content (%)

65 60 50 40

60 50 40

df

16 16 16 16

5 5 5

t AE

-8.06 -0.27

-3.81 -5.53 -4.53

t K/S

-3.03 8.40

-5.77 0.29

-0.31 0.96

-0.49

Level of Significance

AE

NS s s NS

S S S

K/S

S S s NS

NS NS NS

* *

Significant at the a<_ .05 level.

Nonsignificant at the a< .05 level.

Technique Technique Technique Technique Technique Technique Technicjue Technique

1-Disperse 2-Disperse 3-Disperse 4-Disperse 5-Disperse 6-Disperse 7-Disperse 8-Disperse

Blue Blue Blue Red Blue Blue Blue Blue

(2% (1% (3% (2% (2% (2% (2% (2%

w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) , w/w) ,

Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Desized Fabric Benz/Fiber Benz/Bleached Fabric Iron/Desized Fabric Iron/Fiber

60

the known polyester content as determined by gravimetric

measurement and AE reflectance data. There was partial sig­

nificance between the predicted and known polyester content

when K/S data were analyzed for this technique. Technique

6 showed no significant difference at the a<_.05 level from

predicted polyester content with either AE or K/S reflec­

tance data. Technique 7 was found to have mixed signifi­

cance levels for both AE and K/S reflectance data.

Technique 8 indicates a significant difference between pre­

dicted and known polyester content as determined with the

AE data. There was no significant difference between the

predicted polyester content and the known polyester content

as determined with the K/S data at a<_. 05 level.

Hypothesis 2. There are significant differences be­tween the polyester content in desized polyester/ cotton blend fabrics compared to the polyester con­tent in scoured and bleached polyester/cotton blend fabrics as determined by the Thermosol techniques.

The data were analyzed in terms of Hypothesis 2, which

was then partially accepted. Table 14 shows the results of

a comparison for significance at the a<_.05 level between

desized (Technique 1) and bleached fabrics (Technique 6) .

The differences in predicted polyester contents of the

desized, and scoured and bleached samples using AE reflec­

tance data were found to be nonsignificant in all three

levels. The differences in predicted polyester contents of

the desized, and scoured and bleached samples using K/S

51

reflectance data were found to be nonsignificant in 2 of

the 3 blend levels.

TABLE 14

COMPARISON OF DESIZED, AND SCOURED '. AND BLEACHED FABRIC

(t-Test for Statistical Significance)

Nominal Polyester Content

60 50 40

df

5 5 5

t AE

-0.60 2.32

-0.40

t K/S

-4.22 1.73 0.20

Level of S: AE

NS* NS NS

Lgnificance K/S

s** NS NS

* *

'Nonsignificant at the a^.05 level.

Significant at the af_.05 level.

Analysis of Unknown Fiber Blends

As an ultimate test of the validity of one of the sub­

limation analysis techniques for predicting polyester con­

tent, three samples of polyester/cotton fibers of unknown

blend levels were subjected to Technique 8. Technique 8

was identified because it was the technique most likely to

be utilized in a small laboratory situation since it

required only a household type iron as the source of heat.

The raw data for this technique are illustrated in Table 25

(Appendix B). Simple linear regression equations generated

from Technique 8 were used to predict polyester content of

62

these known blend levels. The results of these analyses

are shown in Table 15.

TABLE 15

PREDICTED POLYESTER CONTENT OF "UNKNOWN" FIBER BLEND

(Simple Linear Regression Analysis)

Predicted Polyester Content (%) AE equation

50.4 75.1 11.8

Predicted Polyester Content (%) K/S equation

51.9 86.9 16.3

standard Deviation AE

3.60 2.90 2.81

K/S

4.24 5.70 0.03

The t-test for statistical significance was used to

determine if there was a significant difference between the

known polyester content as determined by gravimetric mea­

surement and polyester content as determined by the subli­

mation Technique 8. Only in one instance did the technique

show statistically significant differences at the a<_.05

level or beyond, this significant relationship occurred .

when the polyester content, as predicted from AE data and

the known polyester content of this blend were compared.

Table 16 summarizes the t-test for statistical significance

for this technique.

TABLE 16

COMPARISON OF "UNKNOWN* TO KNOWN POLYESTER CONTENT

(t-Test for Statistical Significance)

63

Known Polyester Content (%)

52.8 85.0 15.0

df

2 2 2

t AE

1.17 5.94 1.98

t K/S

0.51 -0.51 -0.92

Level of Si AE

NS* S** NS

gnificance K/S

NS NS NS

*Nonsignificant at the a<.05 level. * * Significant at the ci<_.05 level.

CHAPTER V

SUMMARY, CONCLUSIONS AND REC0Mr>4ENDATI0NS

The purposes of this chapter are to summarize the

study and draw conclusions which are based on the analyses

of data collected in the study. Recommendations will also

be made for further research into the Thermosol technique

for the determination of polyester content in polyester

blends.

Summary

A methodology was developed for the prediction of

polyester content in polyester/cotton blends dyed with dis­

perse dyes using a procedure involving sublimation. Reflec­

tance data were used in the prediction equation.

A total of six fabrics of different blend levels were

tested in both the desized, and scoured and bleached states.

Eleven fiber blend levels were also tested. A total of

eight different sublimation techniques were developed and

identified. The polyester contents of the fabric blends

were determined by the AATCC Test Method 20A and the results

were considered to represent the absolute polyester contents.

The actual polyester content of the fiber blends was pre­

determined by gravimetric measurement.

All dissolution and reflectance raw data were presented

Standard deviations were determined for the predicted

64

65

polyester content as determined by simple linear regression

equations using a known variable, either AE or K/S, both of

which were derived from reflectance readings as measured by

a colorimeter. Coefficients of variation, confidence limits

for predicted means and standard errors of the means were

also determined. Ultimately, t-tests for statistical sig­

nificance were used to analyze the two hypotheses developed

at the beginning of the study.

Conclusions Related to Objectives

The following findings and conclusions were related to

preliminary analyses of the raw data using standard devia­

tions, coefficients of variation, standard errors of the

predicted means and coefficients of determination (r ) of

simple linear regression equations. «

1. The first objective was to develop a methodology

for a rapid and accurate procedure to determine polyester

content in polyester/cotton blends that fell within the j 3%

range allowed by the FTC for truth in labeling. From the

standard errors of the predicted means for polyester con­

tents using both AE and K/S reflectance data, it was indi­

cated that individual measurements of the sample fell within

+_ 3% of the mean required for stating blend content in

labeling. This indicated that for the sublimation tech­

niques, individual measurements were accurate within the

66

limits prescribed by law (at the 95% confidence level).

The variation between the predicted means using Technique

5, and the actual means of the fiber blends show that

caution should be taken before applying this particular

technique to the determination of polyester content.

2. The second objective was to standardize rapid

Thermosol techniques using a Benz Unit and a household type

iron as the heat sources. The eight sublimation techniques

developed for this study were standardized in terms of pro­

cedure. It was found that all techniques could be performed

within a 60 minute period.

3. The third objective was to determine if medium or

medium to high energy dyes could be used in the Thermosol

process. It was found that polyester content was accurately

predicted by the sublimation techniques using either energy

dye.

4. The fourth objective was to develop simple linear

regression equations that would accurately predict polyester

content from reflectance data. In three cases, the coeffi-

2 cients or determination (r ) of the simple linear regression

equations which were used to predict the polyester content 2

utilizing reflectance measurements were greater than the r

value of the simple linear regression equation used to pre­

dict the polyester content of desized fabrics based on the

AATCC Test Method. In other words, the three sublimation

67

techniques involved are more accurate methods of predicting

polyester content than the AATCC Test Method (when their r^

values and standard errors are compared). Although the

remaining sublimation techniques resulted in simple linear

regression equations having r^ values less than that of the

equation derived from the AATCC Test Method, the savings in

time and chemicals involved in the sublimation techniques

could well offset the slight reduction in accuracy of these

methods.

5. The fifth objective was to determine the polyester

content of three "unknown" fiber blends using a Thermosol

technique. When the polyester contents of "unknown" fiber

blend level samples were determined using Technique 8,

only one of the fiber blends showed a polyester content sig­

nificantly different from the known polyester content for

that sample. This occurred only when AE reflectance data

were used in the simple linear regression equation.

6. The sixth objective was to compare the accuracy of

the AATCC Test Method 20A and the accuracy of the tetra­

chloroethane test method for determining polyester content.

The results obtained using AATCC Test Method 20A had a pro­

gressively larger standard deviation as the polyester

content of the sample decreased. This indicates that the

accuracy of the test method decreases as the polyester con­

tent decreases. The tetrachloroethane dissolution analysis

68

was shown to have smaller coefficients of determination in

all of the four fabric blend levels than AATCC Test Method

20A. This indicates that the organic solvent technique

produces results that are more accurate and reliable than

the results of AATCC Test Method 20A. With only one ex­

ception, all CV's for a reflectance measurement (either AE

or K/S) were lower than the CV's for the AATCC dissolution

analysis technique.

Conclusions Related to the Hypotheses

Tests of significance at the a<_.05 level resulted in

the following conclusions. The observations are discussed

in the order of the hypotheses.

1. The first hypothesis relating the prediction of

polyester content to reflectance data was the basis for the

following conclusions. The statistical significance levels

between the known polyester contents and the predicted poly­

ester contents at the a; .05 level varied for each sublima­

tion technique depending upon which set of reflectance data

was utilized, AE or K/S. The exception to this was Tech­

nique 6. This technique was found to be the most accurate

for predicting polyester content in fabric blends. Accord-2

ing to the r values and standard errors as determined by

the simple linear regression equations. Technique 8 was

found to be the best method for predicting polyester con­

tent in fiber blends.

69

2. The second hypothesis related polyester content

and the condition of the fabric (desized only or scoured

and bleached) when a Thermosol technique was used to predict

polyester content. The fabric state was found to be a fac­

tor in only one blend level using K/S data. The fabric

state was not a significant factor for any blend level when

AE reflectance data were employed to predict the polyester

content.

Recommendations for Further Research

Recommendations for further research include the

following:

1. A method be developed for the determination of

polyester content in polyester/cotton blends using disperse

dyes other than those used in this study.

2. A method be developed for the determination of

polyester content in polyester/cotton blends using fabric

constructions (e.g., knits, nonwovens, laces) other than

that used in this study.

3. A method be developed for the determination of

polyester content in polyester/cotton blends using heat

sources other than those used in this study (e.g., Thermosol

oven, microwave oven, mangle iron).

4. A method be developed for the determination of

polyester content in polyester/cotton blends containing

polyester types other than that used in this study.

70

5. A method be developed for the determination of

fiber content in other blends using the methodology devel-

oped in this study.

LIST OF REFERENCES

1. Adams, Elliot Q. "X-Z Planes in the 1931 I.C.I. (CIE) System of Colorimetry." Journal of the Optical Society of America 32 (March 1942):168-173.

2. American Association of Textile Chemists and Colorists. Technical Manual of the American Association of Textile Chemists and Colorists 57 (1981-82):46-51, 120-125. •

3. Balchin, T. J. "Dyeing Polyester/Cotton Blend Fabrics in Continuous Application." Crompton and Knowles Corporation, Charlotte, North Carolina, July 28, 1977 (Mimeographed).

4. Balinkin, Isay A. "Measurement and Designation of Small Color Differences." Bulletin of the American Ceramic Society 20 (Novem.ber 1941) : 392-402.

5. Billmeyer, Fred W. and Saltzman, Max. Principles of Color Technology. New York: John Wiley and Sons, 1966, pp. 30,38.

6. Brent, C. J., Flynn, T. D., and Sumner, H. H. "A New insight into the Thermofix Dyeing of Polyester-Cellulose Blends. I-Investigation of the Mechanism of Transfer of Disperse Dyes." Journal of the Society of Dyers and Colourists 85 (December 1969): 606.

7. Celanese Corporation. Man-Made Fiber Dictionary. Celanese Corporation, 1965,, p. 54.

8. Clark, F. R. S., Lambert, P., and Mercier, J. C. "Rapid Quantitative Microanalysis of Multicomponent Fiber Mixtures in Fabrics." Textile Research Journal, (August 1978) :442-446.-

9. Cohen, Allen C. Beyond Basic Textiles. New York: Fairchild Press, 1982, pp. 173, 185.

10. Davidson, Hugh R. and Hanlon, J. J. "Use of Charts for Rapid Calculation of Color Difference." Journal of the Optical Society of America 45 (August 1955): 617-620.

11. Derbyshire, Alan N. "The Development of Dyes and Methods for Dyeing Polyester." Journal of the Society of Dyers and Colourists 90 (August 1974) :273.

71

72

12. Ford, J. E. "Polyester/Cotton." Textiles 9 (February 1980):30-35.

13. Gibson, Joseph W. Jr. "The Thermosol Story." Textile Chemist and Colorist 10 (November 1979) :18 ^ 22"

14. Gorondy, Emery J. "Vapor Fixation of Disperse Dyes in Polyester." Textile Chemist and Colorist 10 (June 1978) :19": "

15. Hoban, Robert F. "Problems Associated with Color Measurements, Reflectance, and Transmittance." Textile Chemist and Colorist 13 (May 1981):16-18.

16. Hunter, Richard S. "Measurement of the Appearance of Paint Finishes." Official Digest 35* (1963):350-366.

17. . "Photoelectric Tristimulus with Three Filters." Journal of the Optical Society of America 32 (September 1942) :509-538.

18. Joseph, Marjorie L. Essentials of Textiles. New York: Holt, Rinehart and Winston, 1977p p. 24.

19. King, Walter D. and Stanonis, D. "Analysis of Cotton/ Polyester Blends with Hexafluoroisopropanol Solvent." Textile Chemist and Colorist 8 (December 1976) :44.

20. . "Determining Polyester in Cotton/Polyester Blends with Tetrachloroethane Solvent." Textile Chemist and Colorist 8 (August 1976) :16-17.

21. King, Walter D., Stanonis, D., and Reid, David. "Determining Polyester in Cotton/Polyester Blends with Monoethanolamine Solvent." Textile Chemist and Colorist 7 (December 1975):28-29.

22. Kuehni, Rolf. Computer Colorant Formulation. Lexington Lexington Books, 1975, pp. 14-15.

23. Kiipper, Harald. Color: Origin, Systems, Uses. New York: Van Nostrand Rienhold Co., 1972, p. 103.

24. Leube, Herbert. "Quality Dyes; Quality Dyeing." Textile Chemist and Colorist 10 (February 1978):36.

25. Linton, George E. The Modern Textile and Apparel Dictionary. Ann Arbor: Braun-Brumfield, Inc., 1973, pp. 2,6.

73

26 Lupton, Christopher, J. Textile Research Center, Lubbock, Texas. Interview, 7 February 1983.

27. MacAdam, David L. "Visual Sensitivities to Color Differences in Daylight." Journal of the Optical Society of America 32 (May 1942) :247-274.

28. Moncrieff, R. w. Man-Made Fibers. 6th ed. New York: John Wiley and Sons, 1975, p. 435.

29. Nickerson, Dorothy. "The Specification of Color Tolerances." Textile Research Journal 6 (19 36): 505-514.

30. Rueckert, Irma. "Determining Polyester in Blends by Using Trichloroacetic Acid." Textile Chemist and Colorist 10 (August 1978) :23-25T

31. Simon, F. T. and Gordon, W. F. "Rapid Graphical Compu­tation of Small Color Differences." American Dyestuff Reporter 47 (February 1958):105-112.

32. Society of Dyers and Colourists. Colour Index. 3rd ed London: Lund Humphries, 19 71, p. 2479.

33. Suchecki, Stanley M. "The State of the Art in Color Science." Textile Industries 8 (August 1979): 130-137.

34. Trotman, E. R. Dyeing and Chemical Technology of Textile Fibers. 5th ed. London: Charles Griffin and Co. Ltd.,1975, pp. 668, 657.

35. . Textile Scouring and Bleaching. London: Charles Griffin and Co. Ltd., 1968, p. 78.

36. Wasserman, Tamar and Basch, Avrham. "Rapid Micro­analysis of Fiber and Fabric Blends." Textile Chemist and Colorist 9 (May 1976):30-31.

APPENDIX A

STATISTICAL ANALYSIS EXPLANATION

APPENDIX A: STATISTICAL ANALYSIS EXPLANATION

Standard Deviation

The standard deviation is a measure of variability, it

takes into account the variability of all observations in

a distribution.

The equation used to determine standard deviation in

this study is as follows:

s =/Zx^ - (Ex)

n-1

where:

n = number of observations

Zx = sum of raw scores squared 2

(Zx ) = sum of raw scores, quantity squared

s = standard deviation

Coefficient of Variation (CV) Coefficient of Variation is a measure of dispersion ex­

pressed as a percent of the mean. This allows standard

deviations to be compared in respect to their representative­

ness without the number of samples interferring in the

comparison.

The equation used to determine CV's in this study is as

follows:

CV = 100 X - ^ X

75

76

where:

s = standard deviation

X = mean

Limits for the Predicted Mean

Limits for the predicted mean are estimates that state

an interval into which the predicted means will fall.

The equation used to determine the limits for the pre­

dicted mean at the 95% confidence level is as follows:.

- _ 2.571 X = X s

where:

X = predicted mean

n = sample size

s = standard deviation

Standard Error of the Mean

Standard error of the mean estimates the limits in which

the mean of the next group of samples would be expected to fall

The equation used to determine the standard error of the

mean is as follows:

s SE- = ^n

where:

SE- = standard error of the mean X

s = standard deviation

n = samole number

77

Simple Linear Regression Analysis

Simple linear regression analysis yields a mathematical

equation for predicting the value of a dependent variable

when given the value of an independent variable using the

least squares model.

The equation used for this analysis is as follows:

y = ax + b

where :

^ ^ Zxy - n ExEy

Zx^ - i - (EX) 2

b = 4- Zy - :^ EX

2 = ^^^y — H ~ (^^^y]^

2 1 2 7 ^ 7

[Zx^ - - ^ (Zx)^][Zy^ - (Zy)^]

2 2 For the Oj r <1, the fit is exact if r = 1

t-Test fo.r Statistical Significance

The purpose of the t-test is to determine the signifi­

cance between two means and determine if the difference is

greater than that which chance would allow. The following

equations was used in this study.

t = X^ - X2

2 ^ 2 =1 + =2

n^ "2

78

where:

degrees of freedom (df) = n -1

^1' ^2 ^ niean of each group 2 2 _

s^ , s^ - variance of each group ^1' ^2 ^ sample size of each group

APPENDIX B

FIBER CONTENT-COLORIMETRIC MEASUREMENT

Tables 17 through 25

TABLE 17

FIBER CONTENT-COLORIMETRIC MEASUREMENT ( T e c h n i q u e l - D i s p e r s e B l u e (2% w / w ) , B e n z / D e s i z e d F a b r i c )

Sample #

1

2

3

4

5

PET Content

Nominal (%)

100

65

60

50

40

Actual (%)

99.9

65.3

63.6

50.1

45.1

AE

75.11 74.18 72.70 73.32 74.09 73.66

57.69 57.81 57.59 57.44 57.29 57.38

55.52 55.07 55.02 55.34 55.83 55.51

51.06 50.89 51.10 50.43 50.01 50.00

47.62 47.45 47.08 47.35 46.41 47.17

Mean AE

73.84

57.53

55.38

50.58

47.18

a AE

0.34

0.20

0.30

0.50

0.43

K/S at X min = 640nm

15.30 14.31 13.51 13.99 14.54 14.59

4.05 4.13 4.05 4.10 4.06 4.06

3.54 3.47 3.45 3.57 3.67 3.56

2.66 2.63 2.64 2.60 2.49 2.60

2.06 2.05 2.02 2.07 2.02 2.05

Mean K/S

14.37

4.07

3.54

2.60

2.04

a K/S

0.60

0.03

0.08

0.05

|o.02

80

81

TABLE 1 7 — C o n t i n u e d

Sample #

6

PET C o n t e n t

N o m i n a l (%)

0

A c t u a l (%)

0

AE

2 5 . 8 8 2 6 . 5 9 2 5 . 3 7 2 7 . 0 8 2 5 . 1 8 2 5 . 2 7

Mean AE

2 5 . 8 9

a AE

0 . 7 8

K/S a t X min = 640nm

0 . 3 4 0 . 3 6 0 . 3 4 0 . 3 9 0 . 3 2 0 . 3 2

Mean K/S

0 . 3 4

a K/S

0 . 0 3

82

TABLE 18

FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 2-Disperse Blue (1% w/w), Benz/Desized Fabric)

Sample #

1

2

3

4

5

6

PET C o n t e n t

N o m i n a l 1

(%)

100

65

60

50

40

0

\ c t u a l (%)

9 9 . 9

6 5 . 3

6 3 . 6

5 0 . 1

4 5 . 1

0

AE

6 8 . 2 4 6 4 . 9 3 6 7 . 1 6 6 5 . 8 0 6 7 . 2 4 6 7 . 2 7

5 4 . 7 6 5 4 . 8 8 5 4 . 3 8 5 4 . 2 0 5 4 . 2 9 5 4 . 9 4

5 2 . 6 0 5 2 . 4 1 5 1 . 9 7 5 2 . 1 2 5 2 . 2 7 5 2 . 0 9

4 8 . 0 8 4 8 . 3 6 4 8 . 9 2 4 8 . 0 4 4 8 . 3 5 4 7 . 7 7

4 5 . 7 9 4 3 . 3 6 4 4 . 8 4 4 5 . 6 1 4 4 . 8 7 4 5 . 0 2

2 8 . 7 7 2 7 . 0 2 3 0 . 5 3 2 7 . 6 9 2 9 . 2 1 2 7 . 2 1

Mean AE

6 6 . 7 7

5 4 . 5 7

5 2 . 2 4

4 8 . 2 5

4 4 . 9 1

2 8 . 4 0

a AE

1.19

0 . 3 7

0 . 2 3

0 . 3 9

0 . 8 5

1 .36

K/S a t X min = 640nm

1 0 . 1 6 7 . 9 2 9 . 2 3 8 . 5 0 9 . 7 8 9 . 5 5

3 . 5 3 3 . 5 0 3 . 5 7 3 . 4 1 3 . 4 9 3 .55

3 . 0 7 3 . 0 1 3 . 0 3 3 . 0 3 3 . 0 5 2 . 9 6

2 . 3 2 2 . 3 5 2 . 3 5 2 . 2 7 2 . 3 2 2 . 3 1

1 .89 1 .81 1.77 1 .85 1 .77

1.82

0 . 5 0 0 . 4 9 0 . 6 1 0 . 5 2 0 . 5 7 0 . 5 0

Mean K/S

9 . 1 9

3 . 4 9

a K/S

0 . 8 3

0 . 0 5

3 .02

2 . 3 2

1.82

0 . 5 3

0 . 0 4

0 . 0 3

0 . 0 4

,0 .58

83 TABLE 19

FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 3-Disperse Blue (3% w/w), Benz/Desized Fabric)

Sample #

1

2

3

4

5

6

PET Content

Nominal (%)

100

65

60

50

40

0

Actual (%)

99.9

65.3

63.6

50.1

45.1

0

AE 76.17 77.54 76.20 76.14 76.08 76.46

58.29 58.16 58.55 57.99 58.09 57.90

57.19 56.97 56.28 56.58 56.24 56.18

52.58 52.43 52.43 52.10 52.12 52.61

40.95 48.50 48.78 48.69 48.79 49.20

39.04 35.21 34.86 35.60 36.05 36.40

Mean AE

76.43

58.16

56.59

52.38

48.83

36.19

a AE

0.56

0.23

0.43

0.22

0.21

1.50

K/S at X min = 640nm

17.26 18.47 17.20 17.13 17.06 17.33

4.34 4.26 4.34 4.21 4.31 4.16

3.88 3.91 3.86 3.77 3.76 3.73

2.86 2.85 2.81 2.79 2.83 2.85

2.30 2.21 2.28 2.23 2.20 2.26

0.81 0.66 0.69 0.69 0.77 0.65

Mean K/S

17.41

4.27

3.82

2.83

2.25

0.71

a K/S

0.53

0.08

0.08

0.02

0.04

0.07

84 TABLE 20

FIBER CONTENT-COLORIMETRIC MEASUREMENT ( T e c h n i q u e 4 - D i s p e r s e Red (2% w / w ) , B e n z / D e s i z e d F a b r i c )

Sample #

1

2

3

4

5

6

PET Content Nominal

(%)

100

65

60

50

40

0

Actual (%)

99.9

65.3

63.6

50.1

45.1

0

AE 76.54 76.58 75.29 76.27 76.15 77.54

56.42 56.71 55.43 56.23 57.20 56.06

55.91 55.60 55.37 55.40 54-20 54.56

51.83 52.17 51.80 52.17 52.04 51.59

48.12 48.09 48.01 48.55 48.03 48.81

31.63 28.94 27.90 32.01 31.52 30.90

Mean AE

76.39

56.34

55.17

51.92

48.27

30.48

0

AE

0.73

0.60

0.65

0.22

0.33

1.66

K/S at X min = 640nm

13.72 13.68 12.61 13.81 13.22 15.30

3.13 3.40 3.00 2.99 3.22 3.02

2.89 2.87 2.77 2.83 2.61 2.65

2.26 2.30 2.25 2.30 2.29 2.23

1.76 1.77 1.75 1.82 1.75 1.84

0.63 0.51 0.48 0.65 0.63 0.59

Mean K/S

13.72

3.13

2.77

2.39

1.78

0.58

a K/S

0.90

0.16

0.11

0.30

0.04

0.07

85 TABLE 2 1

F I B E R CONTENT-COLORIMETRIC MEASUREMENT ( T e c h n i q u e 5 - D i s p e r s e B l u e (2% w / w ) , B e n z / F i b e r )

P E T C o n t e n t Sample

#

N o m i n a l ( % )

A c t u a l ( % ) A E

Mean AE

a AE

K/S a t X min = 640nm

Mean K/S

a K/S

100 9 9 . 9

90 90

80 80

70

60

70

60

50 50

6 7 . 7 0 6 6 . 9 3 6 8 . 2 5 6 7 . 5 5 6 8 . 3 3 6 7 . 2 1

6 3 . 9 9 6 3 . 1 2 6 3 . 5 5 6 3 . 2 9 6 4 . 2 3 6 3 . 1 8

6 0 . 4 4 5 9 . 9 0 6 0 . 7 8 6 0 . 1 1 6 0 . 5 7 6 0 . 8 1

5 5 . 3 4 5 6 . 3 8 5 7 . 7 1 5 8 . 8 6 5 7 . 1 3 5 7 . 6 4

5 4 . 8 2 5 3 . 8 6 5 3 . 0 0 5 2 . 3 9 5 3 . 9 0 5 4 . 2 2

5 0 . 3 6 4 9 . 8 3 5 3 . 0 6 4 9 . 0 7 4 8 . 5 7 5 0 . 1 0

6 7 . 6 6 0 . 5 6

6 3 . 5 6 0 . 4 6

6 0 . 4 3

5 7 . 1 8

0 .38 .

1.20

5 3 . 7 0 0 . 8 7

5 0 . 1 6 1 .57

9 . 4 6 8 .89 9 . 8 0 9 . 2 1 9 . 8 0 9 . 0 7

7 .02 6 . 6 0 6 . 8 1 6 . 6 8 7 . 1 6 6 . 6 1

5 . 3 8 5 . 1 8 5 . 5 0 5 . 2 7 5 . 4 0 5 . 5 5

3 . 6 8 3 . 9 8 4 . 3 7 4 . 1 4 4 . 2 0 4 . 3 7

3 . 5 9 3 . 2 8 3 .14 3 . 0 8 3 .34 3 . 4 9

2 . 6 6 2 . 5 4 3 .14 2 . 4 1 2 . 3 5 2 . 6 6

9 . 3 7 0 . 3 8

6.81 0 .23

5 . 3 8 0 . 1 3

4 . 1 2 0 . 2 6

3.32 0 . 2 0

2 . 6 3 0 . 2 8

86

TABLE 2 1 — C o n t i n u e d

Sample #

7

8

9

10

11

PET C o n t e n t

N o m i n a l ( % )

40

30

20

10

0

A c t u a ] ( % )

40

30

20

10

0

L

AE

4 7 . 3 6 4 7 . 2 9 4 7 . 4 5 4 8 . 2 8 4 5 . 4 7 4 6 . 8 8

4 3 . 4 6 4 2 . 0 8 4 2 . 9 5 4 3 . 1 9 4 3 . 1 8 4 3 . 2 4

3 9 . 8 5 3 9 . 3 1 3 9 . 3 9 4 0 . 4 8 3 9 . 9 2 3 9 . 6 1

3 5 . 9 3 3 5 . 9 8 3 5 . 7 2 3 7 . 0 1 3 5 . 7 1 3 4 . 0 9

3 0 . 4 9 2 9 . 9 3 2 8 . 5 6 3 1 . 7 9 3 1 . 7 2 2 7 . 1 0

Mean AE

4 7 . 1 2

4 3 . 0 2

3 9 . 7 6

3 5 . 7 4

2 9 . 7 6

O

AE

0 . 9 3

0 . 4 9

0 . 4 2

0 . 9 4

1 .67

K/S a t X min = 640nm

2 . 1 8 2 . 1 5 2 . 1 4 2 . 2 9 1 . 9 1 2 . 1 9

1.64 1 .63 1.62 1 .67 1.67 1.74

1.29 1.22 1.26 1 .38 1.30 1 .31

1.00 1 .00

. 9 5 1 .03 1 .00 0 . 8 9

0 . 6 7 0 . 6 0 0 . 5 4 0 . 7 6 0 . 6 3 0 . 5 0

Mean K/S

2 . 6 3

1 .66

1.29

0 . 9 8

0 . 5 9

a K/S

0 . 1 3

0 . 0 4

0 . 0 7

0 . 0 5

0 . 0 9

TABLE 22 87

<T.c.„.,„. . !S-=n;-?S»ir«-»-™= /w), Benz/Bleached Fabric)

Sample #

1

2

3

4

5

PET Content

Nominal (%)

100

60

50

40

0

Actual (%)

99.9

63.6

50.1

45.1

0

AE

72.22 72.40 72.46 72.73 72.71 73.51

54.18 53.72 54.06 54.71 53.77 53.82

49.08 49.11 49.02 49.13 49.12 49.21

47.53 46.81 46.40 46.34 46.86 46.59

23.37 23.60 22.94 24.29 23.47 24.22

Mean AE

72.67

54.04

49.11

46.75

23.64

g

AE

0.44

0.37

0.07

0.43

0.51

K/S at X min = 640nm

13.26 13.34 13.38 13.90 13.85 14.50

3.22 3.13 3.19 3.34 3.15 3.19

2.30 2.31 2.28 2.31 2.31 2.33

2.06 1.96 1.91 1.91 1.97 1.93

0.25 0.28 0.27 0.29 0.26 0.28

Mean K/S

13.71

3.20

2.30

1.96

0.27

0 K/S

0.47

0.08

0.01

0.05

0.01

88 TABLE 23

FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 7-Disperse Blue (2% w/w), Iron/Desized Fabric)

Sample #

1

2

3

4

5

6

PET Content

Nominal (%)

100

65

60

50

40

0

Actual (%)

99.9

65.3

63.6

50.1

45.1

0

AE

69.76 70.77 70.48 70.75 70.57 70.12

56.17 56.64 57.13 57.15 57.42 56.83

54.38 55.30 53.89 54.74 54.36 53.95

50.66 51.16 51.24 50.58 51.36 50.70

47.41 46.79 45.77 47.43 44.01 45.49

34.16 36.03 33.45 32.59 37.36 35.20

Mean AE

70.41

56.89

54.94

50.95

46.15

34.80

a AE

0.39

0.45

1.47

0.34

1.32

1.75

K/S at X min = 640nm

11.28 12.00 12.00 11.94 12.07 11.46

3.88 3.95 4.05 4.06 4.13 4.04

3.37 3.56 3.29 3.45 3.39 3.32

2.61 2.61 2.70 2.63 2.71 2.60

2.10 2.00 1.88 2.09 1.72 1.86

0.70 0.69 0.59 0.54 0.64 0.60

Mean K/S

11.46

4.02

3.40

2.65

2.08

1 0.63

a K/S

0.34

0.09

0.10

0.04

0.14

0.07

89 TABLE 24

FIBER CONTENT-COLORIMETRIC MEASUREMENT (Technique 8-Disperse Blue (2% w/w), Iron/Fiber)

Sample #

1

2

3

4

5

PET Content

Nominal (%)

100

60

50

40

0

Actual (%)

100

60

50

40

0

1

AE

64.58 64.13 66.27 64.39 64.24 65.85

55.30 55.39 55.14 56.27 54.62 55.23

50.96 51.91 52.42 51.07 51.34 52.13

46.48 47.07 47.27 48.69 48.31 47.63

28.16 28.47 28.22 27.20 31.82 30.77

Mean AE

64.91

55.32

51.63

47.57

29.11

a AE

0.91

0.54

0.60

0.82

1.79

K/S at X min = 640nm

7.58 7.02 8.48 7.46 7.39 8.40

3.81 3.79 3.69 4.03 3.63 3.74

2.89 2.99 3.11 2.89 2.93 3.05

2.15 2.23 2.20 2.44 2.38 2.29

0.57 0.60 0.61 0.57 0.78 0.70

Mean K/S

7.73

3.78

2.97

2.28

0.64

a K/S

0.57

0.13

0.09

0.11

0.70

TABLE 25

FIBER CONTENT-COLORIMETRIC MEASUREMENT ("Unknown" Fiber Blends)

90

Sample #

1

2

3 *

Polyester Content (%) Actual Gravimetric

52.8

85.0

15.0

.

AE

52.14 49.09 50.02

61.75 61.39 59.49

33.42 32.88 32.97

Mean AE

50.42

60.88

33.09

a AE

1.40

1.08

0.29

K/S at X min. = 640 nm

3.12 2.53 2.68

6.04 5.96 5.74

0.89 0.89 0.86

•

Mean K/S

2.78

5.74

0.88

a K/S

0.27

0.41

0.02

•Subjected to stripping procedure twice