renewable resource low density materials
TRANSCRIPT
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
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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