PROCESS CHARACTERIZATION OF BIO-FILLER SMC Casey Blabolil and Paula Watt.
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Transcript of 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
5UNDERSTANDING DIFFERENCES
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
6UNDERSTANDING DIFFERENCES
» 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
7UNDERSTANDING DIFFERENCES
» 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
8UNDERSTANDING DIFFERENCES
» Thickening profiles
Brookfield Paste Thickening
9UNDERSTANDING DIFFERENCES
» 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
10UNDERSTANDING DIFFERENCES
» Test geometry
Squeeze flow rheometry
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.
11UNDERSTANDING DIFFERENCES
» Typical raw data
Squeeze flow rheometry
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
Squeeze flow rheometry
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.
13UNDERSTANDING DIFFERENCES
» Results
Squeeze flow rheometry
14UNDERSTANDING DIFFERENCES
» Stress strain curves
Squeeze flow rheometry
15UNDERSTANDING DIFFERENCES
» Viscosity vs. shear rate (average of 5 curves each)
Squeeze flow rheometry
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)
16UNDERSTANDING DIFFERENCES
» Stress Relaxation
Squeeze flow rheometry
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
17UNDERSTANDING DIFFERENCES
» 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
18UNDERSTANDING DIFFERENCES
» 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
19UNDERSTANDING DIFFERENCES
» 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.
Dielectric Cure Analysis
20UNDERSTANDING DIFFERENCES
» data
Dielectric Cure Analysis
21UNDERSTANDING DIFFERENCES
» 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
22UNDERSTANDING DIFFERENCES
» Temperature and pressure –1/8”
Reaktometer Monitoring
time (s)
Tem
pera
ture
( °C
)
CaCO3
Soy filler
23UNDERSTANDING DIFFERENCES
» Temperature and pressure – 1/4”
Reaktometer Monitoring
CaCO3
Soy filler
time (s)
Tem
pera
ture
( °C
)
24UNDERSTANDING DIFFERENCES
» Impedance and displacement – 1/8”
Reaktometer Monitoring
time (s)
Dis
plac
emen
t (m
m)
CaCO3
Soy filler
25UNDERSTANDING DIFFERENCES
» Impedance and displacement – 1/4”
Reaktometer Monitoring
time (s)
Dis
plac
emen
t (m
m)
CaCO3
Soy filler
26UNDERSTANDING DIFFERENCES
» 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
27UNDERSTANDING DIFFERENCES
» 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
28UNDERSTANDING DIFFERENCES
» 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
29UNDERSTANDING DIFFERENCES
» 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
30UNDERSTANDING DIFFERENCES
» 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
31UNDERSTANDING DIFFERENCES
» 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
32UNDERSTANDING DIFFERENCES
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?