process characterization of bio-filler smc casey blabolil and paula watt

PROCESS CHARACTERIZATION OF BIO-FILLER SMC

Casey Blabolil and Paula Watt

2GREEN COST EFFECTIVE LIGHTWEIGHTING

» Weight reduction

» Targeted for volume cost parity to CaCO3

» Local renewable feedstock with no food value

» Industrial market for farmers’ crop by-product

» USDA and State BioPreferred purchasing programs

Why Bio-Filler?

3OVERCOMING BARRIERS

» Water absorption

• Reduced with thermal treatment

» Rheological differences

• Wetout, resin demand, thickening, flow

» Thermoset cure effects

• Avoided with choice of precursor and treatment controls

» Mechanical performance

Why not Bio-Filler?

4UNDERSTANDING DIFFERENCES

SMC Characterization

Compression molding


SMC Characterization» SMC Formula

Formula CaCO3 BioFiller

Ingredients %BOW %BOW

UPE Resin solution 10.8 14.7

LPA 10.8 14.7

Styrene 2.7 3.7

Peroxide 0.3 0.4

Inhibitor 0.2 0.3

Pigment 3.0 4.1

Mold release 1.3 1.8

Thixotrope 0.2 0.3

Filler 43.1 22.6

Thickener 0.5 0.7

Glass Fiber 27.0 36.8

Formula CaCO3 BioFiller

Ingredients %BOV %BOV

UPE Resin solution 19.3 19.3

LPA 19.3 19.3

Styrene 4.9 4.9

Peroxide 0.5 0.5

Inhibitor 0.4 0.4

Pigment 3.8 3.8

Mold release 2.3 2.3

Thixotrope 0.2 0.2

Filler 29.6 29.6

Thickener 0.9 0.9

Glass Fiber 19.0 19.0


» Rheological Behavior

• Thickening profiles

• Squeeze flow rheometry (PPT)

» Cure Characteristics

• Dielectric analysis (DEA)

• Reaktometer Monitoring

» Mechanical Properties

• Flexural and tensile strength and modulus

• Izod impact, notched

• Water absorption

SMC Characterization


» Brookfield DV-III Ultra Programmable Rheometer

• Calibrated with Bookfield Calibration Fluids 12500, 30000, 60000 and 100000.

• SMC paste samples weighing between 400-450 g were poured into 500 ml cans after addition of the thickener.

• Viscosity index was measured periodically at 5 rpm using spindle TF for 36 s.

• A heliopath was used to avoid cavitations during measurement.

Brookfield Paste Thickening


» Thickening profiles

Brookfield Paste Thickening


» Premix Processability Tester (PPT)

• Test principles developed with Dr. Meinecke –University of Akron• Instrument commissioned by Premix, Built by Interlaken

Technology• The instrument is a hydraulic press with 7.62 cm diameter

parallel plates equipped with a load cell to measure stress as a function of sample compression.

Squeeze flow rheometry


» Test geometry


r---------- h

v

F

» 3 plies of SMC are stacked and placed between the

plates, which are initially separated by a 10 mm gap.

» A 10% precompaction to 9 mm is applied prior to start of

test data collection.

» The platens then close at 2 mm/s to 66% compaction.

» The position is held for up to 5 s to monitor stress

relaxation.

» The platens then open and the sample is removed.

» Stress is measured during compression and during the

relaxation hold time.


» Typical raw data


0 1 2 3 4 5 60

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Time (s)

Sh

ea

r S

tre

ss

(M

Pa

)

yield

stress relaxation

precompaction stress

steady state flow

platen stopped

12PPT SQUEEZE FLOW TESTING


r---------- h

v

F

F = loadr = plate radiush = plate separationv= closure rate

n = power law index

𝜏𝐴 = 𝐹𝜋𝑟2

𝛾ሶ = 32 𝑣𝑟(ℎ2)2

𝜇𝐴 = 𝜏𝐴𝛾ሶ = = 23 (ℎ2)2𝐹𝑣𝜋𝑟3

𝜇𝐴 = 𝑚𝛾ሶ𝑛−1

apparent stress

apparent viscosity

shear rate

power law model

Viscosity calculations based on the Stefan equation for shear flow. An infinite plate assumption is employed as a modification for plug flow.


» Results



» Stress strain curves



» Viscosity vs. shear rate (average of 5 curves each)


0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 25

5.2

5.4

5.6

5.8

6

6.2

6.4

6.6

6.8

7

Soy filler

CaCO3

log shear rate (1/s)

log

vis

co

sit

y (

cp

s)


» Stress Relaxation


0 0.5 1 1.5 2 2.5 3 3.5 40

0.2

0.4

0.6

0.8

1

1.2

soy filler

CaCO3

Time (s)

No

rma

lize

d S

tre

ss


» Data

Rheology Data Summary

Filler

Brookfield 2-day paste

viscosity

Brookfield 30-day paste

viscosity

PPT SMC precompaction

stress

PPT SMC compression

modulus

PPT SMC yield

stress

PPT SMC yield strain

PPT SMC viscosity at 10 sec-1

Power Law Index

Relaxation time

(M cps) (M cps) (MPa) (MPa) (MPa) (%) (M cps) (s)

Bio-Filler 9.8 15 0.56 0.22 1.04 5.6 1.3 0.18 2.3

CaCO3 11 19.5 0.23 0.22 0.98 6.1 1.0 0.28 1.3


» Signature Control System SmartTrac® with a 2.54 cm diameter sensor embedded in a 15.24 cm x 15.24 cm mold.

• Samples were molded at 150 °C for 2 min at roughly 7 MPa pressure on 0.32 cm stops.

• Impedance was measured at 1 kHz. • Gel time was defined at the down turn of the resulting impedance

curve, and cure time was the point at which the curve plateaus to a predefined slope limit.

Dielectric Cure Analysis


» Theory

• Impedance is defined as the total opposition a device or circuit offers to the flow of an alternating current (AC) at a given frequency.

• SMC charge completes the circuit and carries current via dipole flipping which is affected inversely by the viscosity of the material.



» data



» SMC Technologie (Dr. Derek GmBH)

• Test prEN ISO 12114

• 4.72 in x 9.84 in mold, thickness range 0.03 in to 0.67 in

• Equipped with thermocouple, pressure transducer, displacement transducer and a dielectric sensor

Reaktometer Monitoring


» Temperature and pressure –1/8”


time (s)

Tem

pera

ture

( °C

)

CaCO3

Soy filler


» Temperature and pressure – 1/4”


CaCO3

Soy filler

time (s)

Tem

pera

ture

( °C

)


» Impedance and displacement – 1/8”


time (s)

Dis

plac

emen

t (m

m)

CaCO3

Soy filler


» Impedance and displacement – 1/4”


time (s)

Dis

plac

emen

t (m

m)

CaCO3

Soy filler


» 1/8” data

» 1/4” data

Cure Data Summary

Filler

Reaktometer Gel time

1/4"

Reaktometer Cure time

1/4"

Reaktometer Start of

exotherm

Reaktometer Time to peak

exotherm

Reaktometer z direction shrinkage

(s) (s) (s) (s) (%)

Bio-Filler 37 124 73 126 0.3

CaCO3 56 117 73 126 0

Filler

Signature Gel time

Signature Cure time

Peak Impedance Final Impedance Reaktometer

Gel time Reaktometer

Cure time

Reaktometer Start of

exotherm

Reaktometer Time to peak

exotherm

Reaktometer z direction shrinkage

QA x-y expansion

(s) (s) (Ω) (Ω) (s) (s) (s) (s) (%) (%)

Bio-Filler 28 100 1353 390 34 72 38 64 -3.7 0.5

CaCO3 38 80 1470 118 65 82 45 80 0 0.5


» Instron 3366

» Specimen cut from compression molded 12 in x 12 in X 1/8 in panels

• Flexural strength and modulus ASTM D790

• Tensile strength and modulus ASTM D638

• Izod impact (notched) ASTM D256

• Water absorption ISO 62 (1)

• Density ISO 1183

Mechanical Performance


» Properties

Mechanical Performance

SMC from Molded

specimen

BBC density Flexural Strength

Flexural Modulus

Tensile Strength

Tensile Modulus

Notched Izod

H2O Abs

(%) (g/cc) (MPa) (MPa) (MPa) (MPa) (J/m) (%)

Bio-FillerSMC

53 1.4 133 7870 75 6460 1020 0.9

std dev 13 1230 13 953 220 0.05

Std density CaCO3 SMC 11 1.8 190 10000 70 12000 1000 0.08

Glass bubble low density

13 1.2 160 7000 65 8000 700 0.2

Low filler low density

0 1.5 220 8000 100 8500 1100 0.6


» Rheological test comparisons

• Paste thickening response was not affected

• In SMC squeeze flow tests the compaction stress was higher for the bio-filler samples, suggesting less loft

• The CaCO3 SMC exhibited a stress overshoot at yield, not seen with

the bio-filler

• Viscosity, at low shear rates, was somewhat higher for the bio-filler material but, with its lower power law index, at high shear rates the curves converge

• Relaxation time for the bio-filler SMC is greater than the CaCO3 SMC,

which may account for the yield overshoot

Conclusions


» Cure analysis comparisons

• The shape of the impedance curves skews the calculated times, inflating the gel time for the CaCO3 SMC and the cure time for the bio-

filler SMC

• Cure timing based on the impedance curves was very similar

• At 1/8” the z-direction shrinkage with the bio-filler was greater but at 1/4” no significant difference was seen, more work is needed to confirm or disprove this

Conclusions


» Mechanical performance

• The bio-filler SMC provided 22% weight savings vs. the standard density SMC

• The bio-filler has a 53% BBC, much higher than other offerings

• Flexural strength was lower for the bio-filler SMC but the tensile strength was at par to the CaCO3 and low density SMCs

• Flexural modulus was at the same level as other low density materials, although the tensile modulus was somewhat lower.

• Impact was similar to the standard density SMC

• Water absorption is higher than for a CaCO3 SMC but at similar levels

to the lower filler, low density SMC

Conclusions


Acknowledgements » Funding

• Ohio Soy Council 15-4-10

» Dr. Coleen Pugh, University of Akron Polymer Science

• Members of the Pugh Research Group

» Collaborating business partners

• Agri-Tech, Union Process and Bunge

33

Thank you

Questions?

process characterization of bio-filler smc casey blabolil and paula watt

Documents

squeeze flow rheometry

paula watt slide

plies of smc

stress relaxation

filler smc casey blabolil

h v f f

load r

resin demand