COMPOSITES 2013

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Composites 2013

American Composites Manufacturing Association

January 29-31, 2013

Orlando, FL - USA

Renewable Resource Low Density Materials

By

Kurt Butler, Premix Inc. (The Composites Group)

Abstract Renewable polymeric technologies using build-

ing blocks derived from biologically renewable materials

have now started to emerge as a viable alternative to pe-

troleum based technologies for the preparation of com-

posite components. Further, mass reduction (light

weighting) technologies are fast becoming a critical topic

for enhancing fuel efficiency. It has become clear that

these two technology areas can be combined to produce

composites that are both friendlier to the environment,

and reduce the overall mass of composite components to

enhance energy efficiencies. The thermoset industry has

seen this opportunity and is currently pursuing com-

pounds that incorporate the as mentioned technologies to

produce compression, and injection moldable materials.

This paper will explore, compare, and demonstrate prop-

erties produced by these renewable resource low density

compounds.

Introduction The greening of the global economy, carbon

footprint sensitivity, increased emphasis on sustainable

systems, and the evolution of product lifecycle analysis

have led many polymeric manufacturers away from the

oil-and -gas wellhead and back to the farm. Indeed, resin

feedstocks derived from plants, just a novelty a few years

ago, are now full-fledged product lines in numerous cas-

es, and are apparently here to stay (1).

Polymeric materials have been prevalent in our

everyday lives for quite a long time. Most of today’s

polymeric materials are derived from nonrenewable pe-

troleum-based feedstock. Instabilities in the regions

where petroleum is drilled, along with an increased de-

mand in petroleum, have driven the price of crude oil to

record high prices. This, in effect, increases the price of

petroleum-based polymeric materials, which has caused

a heightened awareness of renewable alternatives for

polymeric feedstock (2).

The shift away from petroleum feedstocks po-

tentially reduces the importation of oil from unfriendly

nations, in favor of increased consumption of agricultural

products grown closer to home. Additionally, the grow-

ing plants actually sequester carbon dioxide from the at-

mosphere and incorporate it into the plant matter. Sub-

sequent conversion of the plant matter into composites

and further into durable products has a favorable impact

on the carbon footprint.

Today the industrial bio-based product lines

have enormous potential in the chemical and material

industries. The diversity of the biomass feedstocks,

combined with the numerous biochemical and thermo-

chemical conversion technologies (3) have enabled in-

dustries to produce new products, and new production

routes for identical petroleum based feedstocks. See

equations # 1 & 2 for examples of alternate feedstock

routes of bio-based propylene glycol which, is used to

produce various thermoset resins.

Equation # 1(4)

Equation # 2(5)

Natural oils are also commercially available on a large

scale and are relatively low priced. These natural oils can

now be effectively and efficiently turned into usable res-

inous products for the thermoset industry. Natural oils

also have the advantages of low toxicity, high purity and

ready availability, an example of this can be seen in

equation # 3 & 4 that show the use of soy oil to produce

a thermoset resin.

Equation # 3 (6)

Equation # 4 (7)

With new regulations being phased in on in-

creasing fuel efficiency, lighter weight composites are

also of interest as can be seen by the new C.A.F.E (Cor-

porate Average Fuel Economy) standards that have been

released. See figure #1 on C.A.F.E standards for passen-

ger cars and light trucks.

Producing low mass compounds can take nu-

merous avenues. Of interest for this paper are the uses of

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versatile low density microspheres and or microballoons.

With the advent of technology advances to produce bet-

ter suited microspheres, elevated crush strengths, smaller

particle sizes, and favorable bubble densities have ena-

bled composites to push into areas that were not deemed

plausible years ago. They have enabled value creation

both to the manufacturer and final customer.

In efforts to satisfy both green renewable and

low mass capable composites, which are now becoming

the norm, and not so much a novelty as seen in years

past, this paper will explore the combining of the two

technologies to promote renewable low mass composites.

This paper will look at sheet molding compounds and

injection moldable compounds made with renewable bio-

based containing resins in combination with a low densi-

ty additive.

Experimental In the experimental section we will be looking

at SMC's and injection grade compounds produced with

bio-content constituents particularly the thermosetting

resin combined with low density microspheres.

Components for Compound Manufacture

Terms:

SMC - Sheet Molding Compound

MAESO - Maleinated Acrylated Epoxidized Soybean

Oil

PHR - Parts per Hundred Resin

Resins

1. Bio Resin A - MAESO type resin 57% bio-

content in 33% vinyl toluene monomer.

2. Bio Resin B - MAESO type resin 57% bio-

content in 33% styrene monomer.

3. Bio Resin C - Polyester resin with 31 % bio-

content from propylene glycol feed stock in

styrene monomer.

4. Petroleum Based Resin (D) - Polyester resin

5. Petroleum Based Resin (E) - Polyester resin

Monomers

1. Monomer A - vinyl toluene

2. Monomer B - styrene

3. Monomer C - divinyl benzene

Low Profile Systems

1. LP A - thermoplastic in styrene

2. LP B - thermoplastic in vinyl toluene

Initiator

1. Initiator (A) - Peroxymonocarbonate

2. Initiator (B) - Peroxyester

Process Aids

1. Additive A - inhibitor

2. Additive B - inhibitor

3. Additive C - coupling agent

4. Additive D - rheological agent

5. Additive E - surface enhancer

Pigment

1. Black liquid dispersion

Filler

1. Calcium carbonate

Low Density Agent

1. Microsphere A

2. Microsphere B

Thickener

1. Magnesium oxide dispersion (40%)

Reinforcement

1. Glass (A) (1" length)

2. Glass (B) (1/2" length)

See Tables 1, 2 and 3 for formulation break-downs

Paste Blending

All paste for the renewable resource low density

compounds were mixed under a high speed disperser in a

5 gallon pail. Initial process viscosities for the various

compounds can be seen in table # 5.

Compounding

All compounds were produced on a 24" SMC

machine see figure # 2. After compounding of the vari-

ous materials the compounds were allowed to mature to a

comparable molding viscosity.

Mechanical Property Testing

Test panels for the sheet molding compounds

were molded on a 100 ton hydraulic press in a 12" X 12"

plaque tool. The injection test samples were molded on a

250 ton injection press. Mechanical property testing for

the compression molding process was based on ASTM

methods, and the injection molding process was based on

ISO methods. Testing was based on typical transporta-

tion specifications for low density applications as a

method for comparison purposes for the SMC's. The in-

jection bio-based grade compound was compared to typ-

ical higher density injection grade compound ranges.

The physical property data for the compounded SMC's

can be seen in table # 6 and the injection grade com-

pound can be seen in table # 7.

Results & Discussion The SMC blending and compounding processes

did not encounter any issues. The use of the bio-content

resins showed the same SMC processing characteristics

as conventional petroleum based resin SMC systems.

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Normal adjustments were made to the doctor box dams

to accommodate the low density paste so that the appro-

priate amount paste was being deposited on the SMC

carrier film.

The molded SMC mechanical property results

showed systems using the MAESO 57% bio-content

based resin (BIOA5, BIOA6, BIOA7), and the 31% bio-

content polyester resin systems (BIOL5, BIOS1), that the

bio-content low density combination as a whole does not

deteriorate mechanical properties when compared to typ-

ical low density compression molded automotive appli-

cations using petroleum based resins at room tempera-

ture. In some cases the data exhibited higher properties

than typical transportation low density applications (ten-

sile strength, tensile modulus, flexural strength).

Further, when comparing a petroleum resin

based low density system (PETROL5) to the bio-content

based systems low density system (BIOL5, BIOS1); vir-

tually no compromises were seen in the mechanical

properties. See tables # 8 & 9.

Please note that the respective compositions

were closely held to the fiber volume percent content, as

this is critical in low density applications. The reason for

this is to maintain property performance of the com-

pound. Also, note when looking at BIOS1 you will see a

slight change in the PHR amounts when compared to

PETROL5 and BIOL5. This was due to the adjustments

that had to be made because of microsphere density dif-

ferences. See table # 1 and 4. Shrinkage and surface

gloss differences were also noticed between the MAESO

type systems and the bio propylene glycol based systems,

(see table # 6), with the MAESO systems showing

slighter higher shrink and a visually duller (matte) sur-

face.

Additional work is underway to assess how dif-

ferent operating temperatures affect the mechanical

properties of the various compounds.

The injection molded bio-based low density

system could only be compared to conventional higher

density ranges. Very little data is available on conven-

tional petroleum based low density injection moldable

systems. Overall the bio low density injection moldable

compound did quite well in comparison. See table # 10.

Actual part moldings were made by the com-

pression molding process and injection molding process

using the low density bio-content compounds. Compari-

sons were made to show weight saving of the lower den-

sity bio-content moldings to conventional higher density

moldings. See table # 11 and figures # 4-7.

Conclusion Use of bio-content and low density technologies

have seen use for many years in the thermoset industry

mostly as independent technologies. Recently with the

increased awareness of the environment (carbon foot-

print), and the need to become more energy efficient, the

combining of these technologies have potential benefit to

the thermoset industry as can be seen from the data pre-

sented, a combination synergy of both can enhance the

value of current and new products both for the manufac-

turer and end user that are, in combination, friendlier to

the total environment.

Acknowledgments

I would like to acknowledge The Composites

Group for making this paper possible. I would also like

to acknowledge Jon Boomhower, our pilot plant supervi-

sor for producing the SMC and injection compounds

needed for this paper. Additional acknowledgments go to

our technical service and lab service personnel for con-

ducting all the needed molding and testing to produce the

final data.

Author: Author Biography:

Kurt Butler, Research Polymer Chemist, Premix Inc (The

Composites Group).

Over 23 years of thermoset industry experience, BS de-

gree in Chemistry (Youngstown State University) 1987,

MS degree in Macromolecular Science (Case Western

Reserve University) 1995.

References

1. Composites World,

http://www.compositesworld.com/articles/green-resins-

growing-up

Accessed November 27, 2012

2. Energy Citation Database,

http://www.osti.gov/energycitations/product.biblio.jsp?os

ti_id=939375

Accessed November 30, 2012

3. T. M. Carole, J Pellegrino, and M. D. Paster, "Oppor-

tunities in the Industrial Biobased Products Industry",

Applied Biochemistry and Biotechnology, pp. 871, Vol.

113-116, 2004.

4. J. E. McAlvin, Ph.D., Composites 2011, February 2-4,

2011, Ft. Lauderdale, FL USA

5. J. E. McAlvin, Ph.D., Composites 2011, February 2-4,

2011, Ft. Lauderdale, FL USA

6. A. Campanella, Composites 2012, February 21-23

2012, Mandalay Bay Convention Center, Las Vegas, NV

USA

7. A. Campanella, Composites 2012, February 21-23

2012, Mandalay Bay Convention Center, Las Vegas, NV

USA

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8. Wikipedia.org,

en.wikipedia.org/wiki/Corporate_Average_Fuel_Econo

my

Accessed November 26, 2012

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2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026

Fuel

Eff

icie

ncy

(mp

g)

Vehicle Model Year

2011-2025 C.A.F.E Standards for Each Model Year in Miles Per Gallon

"footprint": 41 sq ft or smaller passenger cars

"footprint": 55 sq ft or bigger passenger cars

"footprint": 41 sq ft or smaller light trucks

"footprint": 75 sq ft or bigger light trucks

Figure # 1 New C.A.F.E. Standards through 2025 (8)

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INGREDIENTS PHR (PETROL5) PHR (BIOL5) PHR (BIOS1)

Bio Resin (C) 54.58 53.81

Petroleum Based Resin (D) 54.58

LP (A) 36.40 36.40 35.89

Monomer (B) 9.02 9.02 10.29

Initiator (A) 1.25 1.25 1.29

Additive ( A ) 0.22 0.22 0.23

Additive ( B ) 0.28 0.28 0.29

Additive ( C ) 1.42 1.42 1.58

Additive ( D ) 0.42 0.42 0.43

Pigment 7.63 7.63 7.88

Mold Release 2.36 2.36 2.44

Mold Release 2.36 2.36 2.44

Filler 15.43 15.43 13.82

Microsphere ( A ) 27.86 27.86

Microsphere ( B ) 34.12

Thickener 4.50 4.50 4.64

Glass (A) 41.00 41.00 41.00

Fiber Volume (%) 18.10 18.10 18.70

Table # 1 Formulations with Bio Propylene Glycol Feedstock in the Resin

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INGREDIENT PHR (BIOA5) PHR (BIOA6) PHR (BIOA7)

BIO RESIN (A) 54.4

BIO RESIN (B) 54.4 27.2

BIO RESIN (C) 27.2

LP (A) 36.29 36.29

LP (B) 36.29

MONOMER (A) 9.31

MONOMER (B) 9.31 9.31

INITIATOR (A) 1.29 1.29 1.29

ADDITIVE (A) 0.09 0.09 0.09

ADDITIVE (B) 0.29 0.29 0.29

ADDITIVE (C) 2.01 2.01 2.01

ADDITIVE (D) 0.43 0.43 0.43

PIGMENT 7.74 7.74 7.74

MOLD RELEASE 2.44 2.44 2.44

MOLD RELEASE 2.44 2.44 2.44

FILLER 5.73 5.73 5.73

MICROSPHERE (A) 36.77 36.77 36.77

THICKENER 4.16 4.16 4.16

GLASS (A) 43 43 43

Fiber Volume (%) 17.5 17.6 17.4

Table # 2 Formulations with MAESO Resin

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INGREDIENTS PHR (BIOLD6) (Injection Grade)

Bio Resin (C) 53.14

Petroleum Based Resin (E) 17.69

LP (A) 23.61

Monomer (B) 2.78

Monomer (C) 2.78

Additive (E) 3.33

Initiator (A) 0.39

Initiator (B) 0.83

Additive (A) 0.08

Additive (B) 0.28

Additive (C) 1.67

Pigment 5.56

Mold Release 4.67

Filler 31.67

Microsphere (B) 33.33

Thickener 4.31

Glass 33

Fiber Volume % 15

Table # 3 Injection Grade Formulation with Bio Propylene Glycol Feedstock in the Resin

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MICROSPHERESDensity

(g/cm3

)

Particle Size

(Microns)

Crush Strength

(psi)

Microsphere (A) 0.37 45 3,000

Microsphere (B) 0.46 20 16,000

Table # 4 Microsphere Properties

COMPOUND INITIAL VISCOSITY (cps) BLEND TEMPERATURE 0F

BIOA4 20,000 115

BIOA5 16,000 115

BIOA6 20,800 115

BIOA7 22,400 115

BIOA8 22,400 110

PETROL5 17,000 110

BIOL5 15,000 110

BIOS1 16,000 110

BIOLD6 19,200 110

Table # 5 Process Viscosities

Paste

Paste

Glass

Roving

Doctor

Box

Carrier Film

Doctor

Box

Carrier Film

Compaction

Rollers

Gamma

Gauge

Chopper

Blades

Figure # 2 SMC Machine

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COMPOUND BIOA5 BIOA6 BIOA7 PETROL5 BIOL5 BIOS1

Molded Density (g/cm3) 1.16 1.09 1.17 1.21 1.19 1.22

Gel (sec) 25.53 33.77 26.38 32.46 36.48 35.95

Cure (sec) 92.27 89.18 90.17 87.49 93.99 87.69

Shrink (mils/in) -0.67 -0.67 -0.50 0.00 -0.25 -0.08

Table # 6 Physical Properties

COMPOUND

BIOLD6

Injection

Grade

Molded Density (g/cm3) 1.19

Gel (sec) 18.36

Cure (sec) 42.71

Shrink (mils/in) -0.75

Table # 7 Physical Properties

PROPERTY METHOD UNIT PETROL5 BIOL5 BIOS1 PROPERTY RANGES

12" X 12" 12" X 12" 12" X 12" Typical Tranportation (Low Density Applications)

Tensile Strength ASTM D638 MPa 63 63 71 45 - 60

Tensile Modulus ASTM D638 MPa 7,868 7,826 7,755 6,500 - 7,500

Flexural Strength ASTM D790 MPa 156 161 168 100 - 140

Flexural Modulus ASTM D790 MPa 6,496 6,736 6,680 6,000 - 7,000

Unnotched Izod ASTM D256 J/m 943 918 937 600 - 1,000

Notched Izod ASTM D256 J/m 649 700 642 650 - 900

Moisture Absorption ASTM D570 % 0.28 0.17 0.32 0.60 - 1.30

Glass Content - Burn Out ASTM D2584 % 41.01 40.63 42.00 34 - 48

Specific Gravity ASTM D792 1.21 1.19 1.22 1.20 - 1.45 Table # 8 Mechanical Properties Bio Propylene Glycol Containing Resin Compounds

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PROPERTY METHOD UNIT BIOA5 BIOA6 BIOA7 PROPERTY RANGES

12" X 12" 12" X 12" 12" X 12" Typical Transportation (Low Density Applications)

Tensile Strength ASTM D638 MPa 79 73 72 45 - 60

Tensile Modulus ASTM D638 MPa 7,393 7,654 6,854 6,500 - 7,500

Flexural Strength ASTM D790 MPa 163 153 155 100 - 140

Flexural Modulus ASTM D790 MPa 6,390 6,152 6,195 6,000 - 7,000

Unnotched Izod ASTM D256 J/m 1,272 888 975 600 - 1,000

Notched Izod ASTM D256 J/m 682 699 657 650 - 900

Moisture Absorption ASTM D570 % 0.24 0.18 0.23 0.60 - 1.30

Glass Content - Burn Out ASTM D2584 % 40.41 39.21 41.47 34 - 48

Specific Gravity ASTM D792 1.16 1.09 1.17 1.20 - 1.45 Table # 9 Mechanical Properties MAESO Resin Compounds

PROPERTY METHOD UNIT BIOLD6 PROPERTY RANGES

Injection Molded Conventional Higher Density Injection Molded

Tensile Strength ISO 527 MPa 36 25 - 34

Tensile Modulus ISO 527 MPa 6,959 6,500 - 9,500

Flexural Strength ISO 178 MPa 85 70 - 90

Flexural Modulus ISO 178 MPa 7,142 7,800 - 8,800

Notched Izod ISO 180/1A kJ/m2

18 6.0 - 8.0

Moisture Absorption ISO 62 % 0.29 0.5

Specific Gravity ISO 1183 1.19 1.69 - 1.79 Table # 10 Mechanical Properties Bio Propylene Glycol Containing Resin Injection Compound

PART WEIGHT SAVINGS

Density (g/cm3) Weight (g) Density (g/cm

3) Weight (g) %

A (Compression Molded) 1.83 1,395 1.19 905 35

B (Compression Molded) 1.8 7,900 1.19 5,425 31

C (Compression Molded) 1.51 580 1.19 475 18

D (Injection Molded) 1.74 1,884 1.19 1,249 34

CONVENTIONAL BIO-LOW DENSITY

Table # 11 Molded Part Comparison and Weight Savings

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Conventional Bio - Low Density

Figure # 4 Part A

Conventional Bio - Low Density

Figure # 5 Part B

Conventional Bio - Low Density

Figure # 6 Part C

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Conventional Bio - Low Density

Figure # 7 Part D