2004 training seminars interpreting data

7/23/2019 2004 Training Seminars Interpreting Data

1/57

2004 Training Seminars

DSC

3

Interpreting DSC Data

Glass Transition & Melting


2/57

Glass Transitions

The glass transition is a step change inmolecular mobility (in the amorphous phase of

a sample) that results in a step change in heat

capacity

The material is rigid below the glass transitiontemperature and rubbery above it. morphousmaterials flow! they do not melt (no "#$ melt

pea%)


3/57

Glass Transitions

The change in heat capacity at the glasstransition is a measure of the amount of

amorphous phase in the sample

nthalpic recovery at the glass transition is a

measure of order in the amorphous phase.nnealing or storage at temperatures 'ust

below Tg permit development of order as the

sample moves towards euilibrium

l i


4/57

Heat Flow & Heat Capacity at

the Glass Transition

eat *low

eat $apacity

Temperature +elow Tg, lower $p, lower -olume, lower $T&, higher stiffness, higher viscosity

, more brittle, lower enthalpy

Glass Transition is "etectable by "#$+ecause of a #tep,$hange in eat $apacity

,./

,/.0

,/.1

,/.2

,/.

,/.4

,/.5

,/.3

67777789eat*low

(m:)

/.4

./

.4

;./

eat$apacity($)

2/ 0/ /

Temperature (>$)

&o Hp Hniversal -3.1 T Instruments

Polystyrene


5/57

Measuring!eporting Glass Transitions

" The glass transition is always a temperature range

" The molecular motion associate# with the glasstransition is time #epen#ent$ There%ore Tg increases

when heating rate increases or test %re'uency (MDSC)

DM* D+* etc$, increases$

" -hen reporting Tg it is necessary to state the test

metho# (DSC DM* etc$, e.perimental con#itions

(heating rate sample si/e etc$, an# how Tg was

#etermine# Mi#point 1ase# on Cp or in%lection (pea3 in #eriatie,


6/57

Glass Transition *nalysis

Polystyrene

5$67mg

809Cmin


7/57

Glass Transition *nalysis

Polystyrene

5$67mg

809Cmin


8/57

Step Change in Cp at the Glass Transition

: *morphous ; 0$84


9/57

Aged Epoxy Sample


10/57

Effect of Annealing Time on Shape of Tg


11/57

Importance of Enthalpic Relaxation

Is enthalpic recovery at the glass transition important?

>Sometimes" Glass transition temperature shape an# si/e proi#e use%ul

in%ormation a1out the structure o% the amorphous component

o% the sample$" This structure an# how it changes with time is o%ten

important to the processing storage an# en#?use o% a

material$" +nthalpic recoery #ata can 1e use# to measure an# pre#ict

changes in structure an# other physical properties with time$


12/57

+%%ect o% *ging on *morphous Materials

Temperature

Max TgStorage

timeH

MS

+'uili1rium

@i'ui#

+'uili1rium

Glass

Aau/mannTempB @owest Tg

(+ntropy o% Crystal,

-here H ; High relatie cooling rate

M ; Me#ium relatie cooling rat

S ; Slow relatie cooling rate

Decreases+ntropy

Decreases+nthalpy

DecreasesHeat Capacity

DecreasesCoe%%icient o%+.pansion

ncreasesMo#ulus

DecreasesSpeci%ic olume

!esponse on

S

Physical Property

+ntropy

+nthalpy

Coe%%icient o%

Mo#ulus

Speci%ic olume

!esponse on

Storage Eelow Tg

Physical Property

!


13/57

Suggestions %or Fin#ing -ea3

Glass Transitions" Anow your empty?pan 1aseline

" Get as much material in the amorphous state

" Cool slowly through the glass transition

region

" Heat rapi#ly through glass transition region

" se MDSC)

" r use uasi?sothermal MDSC


14/57

Glass Transition Summary

" The glass transition is #ue to *morphous

material

" The glass transition is the reersi1le change

%rom a glassy to ru11ery state & ice?ersa

" DSC #etects glass transitions 1y a step

change in Cp


15/57

Melting De%initions

" Melting the process o% conerting crystalline

structure to a li'ui# amorphous structure

" Thermo#ynamic Melting Temperature the

temperature where a crystal woul# melt i% it ha# a

per%ect structure (large crystal with no #e%ects,

" Metasta1le Crystals Crystals that melt at lower

temperature #ue to small si/e (high sur%ace area, an#poor 'uality (large num1er o% #e%ects,


16/57

De%initions (cont$," Crystal Per%ection the process o% small less per%ect

crystals (metasta1le, melting at a temperature 1elowtheir thermo#ynamic melting point an# then (re,

crystalli/ing into larger more per%ect crystals that

will melt again at a higher temperature

" True Heat Capacity Easeline

o%ten calle# thethermo#ynamic 1aseline it is the measure# 1aseline

(usually in heat %low rate units o% m-, with all

crystalli/ation an# melting remoe#>$ assumes no

inter%erence %rom other latent heat such as

polymeri/ation cure eaporation etc$ oer the

crystalli/ationmelting range


17/57

Melting o% n#ium

42./>$

4./>$;1.4/$=min

,;4

,;/

,4

,/

,4

/

eat*low(m

:)

4/ 44 / 4

Temperature (>$)

&Go Hp Hniversal -5./+ T Instruments

@ea% Temperature

trapolated

Jnset

Temperature

eat of

*usion

*or pure! low

molecular weight

materials (mwK4//

g=mol) usetrapolated Jnset as

Melting Temperature


18/57

Melting o% P+T

;50.2/>$

;3.4>$4;.0$=min

,2

,

,4

,5

,3

,;

,

eat*low(m:)

;// ;/ ;;/ ;3/ ;5/ ;4/ ;/ ;2/

Temperature (>$)


trapolated

Jnset

Temperature

@ea% Temperature

eat of

*usion

*or polymers! use @ea% as Melting Temperature


19/57

Comparison o% Melting

;50.2/>$

;3.4>$4;.0$

4./>$;1.4/$=min

@&T.20mg/>$=min

,;4

,;/

,4

,/

,4

/

eat*low(m:)

5/ / 1/ ;// ;;/ ;5/ ;/ ;1/

Temperature (>$)&Go Hp Hniversal -5./+ T Instruments


20/57

*naly/ingnterpreting !esults

" t is o%ten #i%%icult to select limits %orintegrating melting pea3s

ntegration shoul# occur 1etween two points on

the heat capacity 1aseline

Heat capacity 1aselines %or #i%%icult samples can

usually 1e #etermine# 1y MDSC)or 1y

comparing e.periments per%orme# at #i%%erent

heating ratesSharp melting pea3s that hae a large shi%t in the

heat capacity 1aseline can 1e integrate# with a

sigmoi#al 1aseline


21/57

Easeline Due to Cp


22/57

Easeline Type


23/57

"SC of #olymer $lend

-here is theCp 1aselineI

More on this sample in

the MDSC) section


24/57

s it a meltI

J+SK

nset shi%ts 1y only 0$=9C


25/57

s it a MeltI

LK

nset shi%ts 1y almost =09C


26/57

+%%ect o% Heating !ate on Melting

/>$=min

4/>$=min

//>$=min

4/>$=min

/

;

5

1

/

eat$apacity($)

,5/ / 5/ 1/ ;/ / ;// ;5/ ;1/Temperature (>$)

Melt


27/57

+%%ect o% Heating !ate on Polymorph

"#$ at $=min

"#$ at /$=min

"#$ at 4/$=min

"#$ at $=min


28/57

+%%ect o% mpurities on Melting

ffect of p,minobenAoic cid Impurity $oncentration

on the Melting #hape=Temperature of @henacetin

ppro. mg

$rimped l @ans

;>$=min

L+# 45

Thermal nalysis@urity #et

Melting of

utectic Miture

// @ure

04./ @ure

00.3 @ure

0./ @ure


29/57

ant Ho%% Purity Calculation

33./

33.4

35./

35.4

34./

Temperatur

e(>$)

,; / ; 5 1 /

Total rea = @artial rea

;4.;/>$32.24>$

@urity? 00.43mol Melting @oint? 35.0;>$ (determined)"epression? /.;4>$"elta ? ;.44%$NM# "eviation? /./>$

,;.;

,;./

,.1

,.

,.5

,.;

,./

,/.1

eat*low(:=g)

;; ;5 ; ;1 3/ 3; 35 3 31

Temperature (>$)&Go Hp

5


30/57

2004 Training Seminars

DSC

5

Interpreting DSC Data

$rystalliAation! eat $apacity!

and $rosslin%ing


31/57

CrystallinityDe%initions

" Crystalli/ation the process o% conerting eithersoli# amorphous structure (col# crystalli/ation on

heating, or li'ui# amorphous structure (cooling, to a

more organi/e# soli# crystalline structure

" Crystal Per%ection the process o% small less per%ect

crystals (metasta1le, melting at a temperature 1elow

their thermo#ynamic melting point an# then (re,

crystalli/ing into larger more per%ect crystals thatwill melt again at a higher temperature

"


32/57

Change in Crystallinity -hile Heating

/4.//>$;24.//>$

35.3>$

;2.1>$/.122$

;3/./>$

2.0$)


Ouenched @T

0.4mg

/>$=min


33/57

Crystalli/ation

" Crystalli/ation is a 3inetic process which can 1e

stu#ie# either while cooling or isothermally

" Di%%erences in crystalli/ation temperature or time(at a speci%ic temperature, 1etween samples can

a%%ect en#?use properties as well as processing

con#itions

" sothermal crystalli/ation is the most sensitie wayto i#enti%y #i%%erences in crystalli/ation rates


34/57

Crystalli%ation

" Crystalli/ation is a two step processN

LucleationGrowth

" The onset temperature is the nucleation (Tn,

" The pea3 ma.imum is the crystalli/ation

temperature (Tc,


35/57

/./

/.4

./

.4

;./

eat*lo

w(:=g)

5/ 4/ / 2/ 1/ 0/ // / ;/ 3/ 5/ 4/ /

Temperature (>$)&Go Hp

P@JP!PJ@+L+-TH LC@+*TLG

*G+LTS

P@JP!PJ@+L+-THT

LC@+*TLG *G+LTS

,.4

,./

,/.4

/./

eat*low(:=g)

/ 1/ // ;/ 5/ / 1/ ;//

Temperature (>$)&o Hp

crystalli%ation

melting

+%%ect o% Lucleating *gents

-h i h l C lli i I


36/57

-hat is sothermal Crystalli/ationI

" * Time?To?+ent +.periment

*nnealing Temperature

Melt Temperature

sothermal Crystalli/ation

Temperature

Tem

perature

Time

Oero Time

h l C lli i


37/57

sothermal Crystalli/ation

117.4 oC

117.8 oC

118.3 oC

118.8 oC

119.3 oC

119.8 oC120.3 oC

0

1

2

3

4

5

HeatFlow

(mW

!1 1 3 5 7 9

"ime (min

@olypropylene


38/57

Speci%ic Heat Capacity (Cp,

" Heat capacity is the amount o% heat re'uire# to

raise the temperature o% a material 1y 89C %rom T8

to T2

" True Heat Capacity (no transition, is completely

reersi1leB the material releases the same amount

o% heat as temperature is lowere# %rom T2to T8

"Speci%ic Heat Capacity re%ers to a speci%ic massan# temperature change %or a material (g9C,

-h i H C i I


39/57

-hy is Heat Capacity mportantI

" *1solute thermo#ynamic property (s$ heat

%low, use# 1y engineers in the #esign o%

processing e'uipment

" Measure o% molecular mo1ility Cp increases as molecular mo1ility increases$

*morphous structure is more mo1ile than crystalline

structure

" Proi#es use%ul in%ormation a1out the

physical properties o% a material as a %unction

o% temperature


40/57

Does DSC Measure Heat CapacityI

" DSC or MDSC) #o not measure heat

capacity #irectly$ They measure heat %low ratewhich can 1e use# to calculate heat capacity

which is more appropriately calle# apparent

heat capacity DSC calculate# Cp signals inclu#e all transitions 1ecause

the heat %low signal is simply #ii#e# 1y heating rate (an

e.perimental constant, to conert it to heat capacity units

* true alue o% Cp can only 1e o1taine# in temperatureregions where there are no transitions

C l l i H C i (C ,


41/57

Calculating Heat Capacity (Cp,

" Depen#ing on the DSC that you hae there

are three #i%%erent ways to calculate Cp8, Three !un Metho# *STM +8265

*pplica1le to all DSCQs

2, Direct Cp Single !un Metho# *pplica1le to 8000 only

=, MDSC) ? Single !un Metho#

*ny T* nstruments DSC w MDSC option

Most accurate #etermination


42/57

Cp 1y Stan#ar# DSC

" Generally three e.periments are run in aDSC oer a speci%ic temperature range

+mpty pan run

Sapphire run

Sample run

C l l ti C 1 St # # DSC


43/57

Calculating Cp 1y Stan#ar# DSC

" Three e.periments are run oer a speci%ic

temperature range *llow < minute isothermal at start se 209Cmin heating rate

8$ +mpty pan run Match panli# weights to R 0$0< mg

se# to esta1lish a re%erence 1aseline



44/57


2$ Sapphire run

se# to #etermine cali1ration constant se same weight o% panli# as %or 1aseline R

0$0< mg

Typical weight is 20 2< mg

=$ Sample run Typical weight is 80 8< mg

se same weight o% panli# as 1e%ore R 0$0< mg

C 1 T #iti l DSC = !


45/57

Cp 1y Tra#itional DSC = !uns

,//

/

//

;//

3//

5//

Temperature

(>$)

,3/

,;4

,;/

,4

,/

,4

/

4

eat*low(m:)

/ / ;/ 3/ 5/

Time (min)

eat *low

+aseline Nun

#ample Nun

$alibration Nun

1 #i i l


46/57

Cp 1y Tra#itional DSC = !uns

/

//

;//

3//

5//

4//

Totaleat($)

4/.// >$. $

4/.// >$./0 $

;1/.// >$.0;5 $

;1/.// >$

545. $25. $35.05


47/57

Speci%ic Heat Capacity

" MDSC) & T/ero DSC hae the a1ility

to calculate a heat capacity signal #irectly

%rom a single run$

" Eene%its o% using a heat capacity (instea# o%heat %low, signal inclu#eNThe a1ility to oerlay signals %rom samples run

at #i%%erent heating ratesThe a1ility to oerlay signals %rom heating an#

cooling e.periments

Direct Cp %rom a 8000


48/57

Direct Cp %rom a 8000

;24.//>$43/.1$

/.23$)

/ 4/ // 4/ ;// ;4/ 3//

Temperature (>$)

Hniversal -3.1 T Instruments

Fatent eat of

Melting is Lot eat

$apacity

Fatent eat of

$rystalliAation is Lot

eat $apacity

bsolute integral

calculates total heat


49/57

Heat Flow w Di%%erent Heating !ates

Heat Flow Signal# In$rea#e in Si%e

wit& In$rea#ing Heating 'ate

E %it % Pl tti H t C it


50/57

Eene%it o% Plotting Heat Capacity

Nemember! "#$ and M"#$

$p signals are really

Apparent Cp signals;

crystalliAation and melting

are latent heats! not $p

eat $apacity #ignals reLormaliAed for eating Nate and

@ermit $omparison of periments

"one at "ifferent eating Nates

H t Fl & C Si l


51/57

Heat Flow & Cp Signals

PolypropyleneSi/eN 5$28 mg

DSC Cycle 80#egCmin

Heat Capacity on Heating

Heat Capacity on Cooling

Heat Flow on Heating

Heat Flow on Cooling

-ea3 Tg isi1le in Cp Signal


52/57

-ea3 Tg isi1le in Cp Signal

SampleN Polypropylene

Si/eN 5$28 mg

DSC Cycle 80Cmin

Heat Capacity on Heating

Heat Capacity on Cooling


53/57

Thermoset Curing & !esi#ual

Cure" * UthermosetV is a cross?lin3e# polymer

%orme# 1y an irreersi1le e.othermic

chemical reaction* common e.ample woul# 1e a 2 part epo.y

a#hesie

" -ith a DSC we can loo3 at the curing o%these materials an# the Tg o% %ull or

partially cure# samples

Curing o% a Thermoset


54/57

Curing o% a Thermoset

34.;>$

01.34>$;41.3$=min to 0/ >$

5

1

/

;

eat*low

(m:)

5/ / 1/ // ;/ 5/ / 1/ ;//

Temperature (>$)

# ti ll C d S t


55/57

#artially Cured System

;ndheat shows increased

Tg! due to additional

curing during st heat

Lote? #mall eotherm due to residual cure

Ph l C 1 PC*


56/57

Photopolymer Cure 1y PC*

./1min

./min;/0.$;? Isothermal for .// min3? Fight? on B ;/m:=cm;5? Isothermal for 4.// min4? Fight? off? Isothermal for ;.// min2? &nd of method

$ure of a @hotopolymer by @$

/

4/

//

4/

;//

;4/

eat*low

(m:)

/ ; 5 1

Time (min)


57/57

2004 training seminars interpreting data

Documents