Application of Bio-based Composites for the Automotive Industry: Material Characteristics of Switchgrass Biochar-Reinforced Polypropylene

Open Access
- Author:
- Ishihara, Hisaaki
- Graduate Program:
- Biorenewable Systems
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- February 25, 2021
- Committee Members:
- Jeffrey M Catchmark, Thesis Advisor/Co-Advisor
Alicyn Marie Rhoades, Committee Member
Stephen C Chmely, Committee Member
Paul Heinz Heinemann, Program Head/Chair - Keywords:
- biochar
switchgrass
polypropylene
surface modification
pyrolysis
thermal modification
Biochar
Switchgrass
Polypropylene
Surface modification
Pyrolysis
Thermal modification - Abstract:
- The automotive industry addresses environmental issues such as greenhouse gas emissions and end-of-life vehicle waste management by developing lighter materials that generate less waste. Biobased composites that use plant-based fillers with a resin matrix have attracted much attention as one avenue in addressing these environmental concerns. Lighter than conventional reinforcements such as talc and glass fibers, biobased fibers act as practical and abundant natural fillers for composites. Also, such composites create less waste because natural fibers are biodegradable and combustible. Biobased composites, however, often exhibit inferior mechanical properties due to poor adhesion between the biobased fiber surface and the hydrophobic polymer matrix. In this research, pyrolysis treatments were examined to modify switchgrass fiber’s surface. The thermal treatment causes a reduction of hydroxyl groups and facilitates porosity on the biofiber’s surface. These changes can enhance the adhesion between the biofiber and the polymer matrix. Samples with different pyrolysis temperatures (300℃, 750℃) and loading (10%, 20%) were molded with polypropylene (PP) by an industrial-scale injection molding machine. Also, the raw switchgrass, talc, and neat PP were used as controls. These samples were tested for tensile strength, Izod impact, and flexural modulus. The results showed that the PP resin penetrated some pores on the biochar surface, and the hydroxy groups were reduced. Also, an improvement in flexural modulus was observed with reduced weight. While there are a few studies on switchgrass biochar composites, this research adopts a unique and comprehensive approach to optimize the filler and matrix’s miscibility to improve mechanical performance.