Green Composites From Biofibers and Soy protein based Bioplastics

摘要

Expanding global production and consumption of polymer materials together with increasing public awareness of environmental issues have created serious concern about the problems related to the disposal of plastic waste. Biodegradable plastics and their composites with natural fibers - - the so-called "green" composites --- are finding broad acceptance with the public as natural and environmentally friendly materials. In view of the above, soy protein based bio-plastics have gained significant interest for various applications and are being considered as a potential alternative to petroleum based polymers. Poor strength and stiffness of soy-based plastics limit their applications in some areas. This problem can be solved by the addition of natural/bio-fibers to the soy-based plastics. This paper discusses the fabrication of soy protein based bio-plastics and their bio-composites and characterization of their mechanical and thermal properties. The usual extrusion and injection molding processing techniques are adopted in fabricating both the bioplastics and biocomposites. A considerable enhancement in tensile, flexural and impact properties was observed with the inclusion of natural fiber (industrial hemp) in soy plastics. The tensile strength, flexural strength, tensile modulus and flexural modulus values of this composite (with 30 wt.% hemp fiber) increased by as much as 125%, 850%, 300% and 1050% respectively in comparison to soy flour-based bio-plastics. Improvement in impact properties of the bio-composite was also observed. Thermal studies show an increase in the heat deflection temperature by about 35℃ with the addition of the 30-wt% natural fiber. The effect of higher fiber loading on the physico-mechanical performance of the resulting "green" composites is reported.