Thermal, Mechanical, and Physical Properties of Wood-Plastic Composites with Added BiocharDavid DeVallance,Gloria Oporto,George Cheng, andPatrick Quigley
GOALS & OBJECTIVES The long-term goal of this research: • Integrate bio-energy related by-products, particularly biochar, with plastics and wood by- products to create sustainable composite products The objective in this project: • To combine biochar with wood flour and polymeric materials (i.e., plastics) to fabricate a novel composite material
BACKGROUND• Wood and most polymers (i.e., plastics) are not compatible• Polymers – hydrophobic (i.e., non-polar)• Wood – hydrophilic (i.e., polar)• Traditional WPC’s use coupling agents• Most WPCs undergo some UV degradation and lighten over time (Falk et al. 2001)• Carbon black – additive to reduce UV degradation• There is a need to identify alternative, environmentally friendly materials that can replace the currently used additives in WPCs• Biochar - Viable replacement for WPC additives?
BACKGROUNDBiochar• By-product of slow pyrolysis processes used to produce gas and bio-oil (Sohi et al., 2009)• Exhibits a hydrophobic nature (Maciejewska, et al. 2006)• Should reduce UV degradation in WPCs• Has a higher ignition temperature, as opposed to wood fiber (Antal and Gronli, 2003)• Should be more thermal resistant than wood
EXPERIMENTAL Wood (yellow-poplar), Biochar (mixed hardwoods), and Polypropylene (with lubricant) were combined to form composites
EXPERIMENTAL Component were mixed using a Haake PolyDrive blender Composite specimens for physical and mechanical analysis prepared using a Carver Hot press (Temp. 200°C, Pressure 8.9 kN)
EXPERIMENTAL Mechanical properties evaluated using an Instron Universal Test Machine Water absorption and swelling were measured after 24 and 48 hours Thermogravimetric analysis (TGA, DTGA) was performed
TEST RESULTS: Bending Composites with biochar Box-and-Whisker Plot Flexural Strength (MPa) included resulted in a 24 statistically significant 20 higher flexure strength 16 (MOR), as compared to 12 the composites without 8 biochar Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5 Group Summary Modulus of Rupture, MOR (MPa) Statistic 40/0/60 35/5/60 25/15/60 15/25/60 0/40/60 Average 16.1 19.4 20.4 21.3 19.5 St. Dev. 4.3 1.4 1.6 1.5 2.3 COV % 26.7 7.1 7.7 7.2 11.8 Minimum 8.7 17.0 17.6 18.4 15.8 Maximum 23.6 21.6 23.0 23.6 22.4
TEST RESULTS: Tension Box-and-Whisker Plot While two composites Tensile Strength (MPa) 15.9 that included biochar 13.9 (5% and 15%) resulted in higher average tensile 11.9 strengths, the 9.9 differences were not 7.9 statistically significant Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5 Group Summary Tensile Strength, Ft (MPa) Statistic 40/0/60 35/5/60 25/15/60 15/25/60 0/40/60 Average 11.2 12.5 12.0 10.8 11.0 St. Dev. 1.4 1.3 1.3 1.3 0.9 COV % 12.6 10.1 11.1 12.3 8.1 Minimum 9.4 10.2 9.6 7.9 9.0 Maximum 14.3 14.4 14.9 12.5 12.4
TEST RESULTS: Water Absorption Water absorption is reduced by 25%, 51% and 73% after the incorporation of 5%, 15% and 25% biochar
TEST RESULTS: Swelling Although reduction in swelling is observed after the addition of biochar, no statistically significant difference was found
TEST RESULTS: Thermogravimetric Analysis (TGA & DTGA) Considering a 10% of weight loss, biochar increase the composite decomposition temperature from 315°C to 360°C when 15% is added to the mixture
Major ConclusionsAddition of biochar appears to have:1. Improved strength properties,2. Improved thermal degradation properties, and3. Reduced water absorptionOn-going researchResearch is underway to evaluate:1. Potential improvements in UV degradation,2. Flame resistance,3. Conductivity,4. Mechanical properties with the incorporation of coupling agent, and5. Microbial degradation after the incorporation of biochar in wood-plastic composites (WPCs)
Questions?Further Information: firstname.lastname@example.orgAcknowledgments:Dr. Rakesh Gupta, Chair of the Chemical EngineerDepartment at West Virginia University, for giving usaccess to some laboratory equipment
References: Antal, M.J. and Gronli, M. 2003. The art, science, and technology of charcoal production. Ind. Eng. Chem. Res. 2003(42):1619-1640. Falk, R.H., T. Lundin, and C. Felton, 2001. Accelerated weathering of natural fiber-thermoplastic composites: Effects of ultraviolet exposure on bending strength and stiffness. In: Proc. Sixth International Conference on Woodfiber- Plastic Composites. Forest Prod. Soc., Madison, WI. pp. 87-93. Maciejewska, A., H. Veringa, J. Sanders, and S.D. Peteves. 2006. Co-firing of biomass with coal: Constraints and role of biomass pre-treatment. DG JRC Institute for Energy. Retrieved October 21, 2010, from <http://www.techtp.com/Cofiring/Cofiring%20biomass%20with%20Coal.pdf> Sohi, S., E. Lopex-capel, E. Krull, and R. Bol. 2009. Biochar, climate change and soil: A review to guide future research. CSIRO Land and Water Science Report. Retrieved April 28, 2010, from, <http://www.csiro.au/files/files/poei.pdf>.