Process Characterization of Bio-filler SMC Casey Blabolil and Paula Watt

Green Cost effective Lightweighting Why Bio-Filler? 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 Green Cost effective Lightweighting

Why not Bio-Filler? Overcoming 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 Overcoming Barriers

Understanding differences SMC Characterization Compression molding Understanding differences

Understanding differences SMC Characterization SMC Formula Formula CaCO3 BioFiller Ingredients %BOW UPE Resin solution 10.8 14.7 LPA Styrene 2.7 3.7 Peroxide 0.3 0.4 Inhibitor 0.2 Pigment 3.0 4.1 Mold release 1.3 1.8 Thixotrope Filler 43.1 22.6 Thickener 0.5 0.7 Glass Fiber 27.0 36.8 Formula CaCO3 BioFiller Ingredients %BOV UPE Resin solution 19.3 LPA Styrene 4.9 Peroxide 0.5 Inhibitor 0.4 Pigment 3.8 Mold release 2.3 Thixotrope 0.2 Filler 29.6 Thickener 0.9 Glass Fiber 19.0 Understanding differences

Understanding differences SMC Characterization 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 Understanding differences

Understanding differences Brookfield Paste Thickening 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. Understanding differences

Understanding differences Brookfield Paste Thickening Thickening profiles Understanding differences

Understanding differences Squeeze flow rheometry 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. Understanding differences

Understanding differences Squeeze flow rheometry Test geometry 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. r ---------- h v F Understanding differences

Understanding differences Squeeze flow rheometry Typical raw data precompaction stress steady state flow platen stopped Understanding differences

PPt Squeeze flow Testing Squeeze flow rheometry r ---------- h v F Viscosity calculations based on the Stefan equation for shear flow. An infinite plate assumption is employed as a modification for plug flow. apparent stress apparent viscosity shear rate power law model F = load r = plate radius h = plate separation v= closure rate n = power law index PPt Squeeze flow Testing

Understanding differences Squeeze flow rheometry Results Understanding differences

Understanding differences Squeeze flow rheometry Stress strain curves Understanding differences

Understanding differences Squeeze flow rheometry Viscosity vs. shear rate (average of 5 curves each) Understanding differences

Understanding differences Squeeze flow rheometry Stress Relaxation Understanding differences

Understanding differences Rheology Data Summary Data 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) (MPa) (%) (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 0.98 6.1 1.0 0.28 Understanding differences

Understanding differences Dielectric Cure Analysis 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. Understanding differences

Understanding differences 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. Understanding differences

Understanding differences Dielectric Cure Analysis data Understanding differences

Understanding differences Reaktometer Monitoring 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 Understanding differences

Understanding differences Reaktometer Monitoring Temperature and pressure –1/8” Temperature ( °C) CaCO3 Soy filler time (s) Understanding differences

Understanding differences Reaktometer Monitoring Temperature and pressure – 1/4” CaCO3 Temperature ( °C) Soy filler time (s) Understanding differences

Understanding differences Reaktometer Monitoring Impedance and displacement – 1/8” CaCO3 Displacement (mm) Soy filler time (s) Understanding differences

Understanding differences Reaktometer Monitoring Impedance and displacement – 1/4” CaCO3 Displacement (mm) Soy filler time (s) Understanding differences

Understanding differences Cure Data Summary 1/8” data 1/4” data Understanding differences

Understanding differences Mechanical Performance 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 Understanding differences

Understanding differences Mechanical Performance Properties SMC from Molded specimen BBC density Flexural Strength Flexural Modulus Tensile Strength Tensile Modulus Notched Izod H2O Abs (%) (g/cc) (MPa) (J/m) Bio-Filler SMC 53 1.4 133 7870 75 6460 1020 0.9 std dev   13 1230 953 220 0.05 Std density CaCO3 SMC 11 1.8 190 10000 70 12000 1000 0.08 Glass bubble low density 1.2 160 7000 65 8000 700 0.2 Low filler low density 1.5 100 8500 1100 0.6 Understanding differences

Understanding differences Conclusions 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 Understanding differences

Understanding differences 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 Understanding differences

Understanding differences 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 Understanding differences

Understanding 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 Understanding differences

Thank you Questions?