Valorization of waste protein biomass for bio-based plastics, composites and adhesives development

Abstract

The increasing demand and cost escalation of raw materials for industrial chemicals, materials and energy impel the development of sustainable strategies of resource utilization. Such resource demand spurred investigation for the utilization of agricultural wastes and by-products. The emergence of bovine spongiform encephalopathy (BSE) reduced most of the traditional uses of rendered animal meals such as blood meal, meat and bone meal as animal feed. The purpose of this research was to valorize rendering industry wastes for preparation and synthesis of bio-based products. Specified risk materials (SRM) were hydrolyzed according to two protocols approved by the Canadian Food Inspection Agency and Food and Drug Administration and the recovery of proteinacious fragments for non-food/feed value-added applications were evaluated. Cleavage of recovered proteinacious materials and other characteristics were evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), size exclusion high performance liquid chromatography (SEC-HPLC), and free amino acid determination methods. The recovered protein hydrolyzates were modified through chemical crosslinking to develop a thermosetting protein based plastics. The plastics made by the crosslinking of protein hydrolyzates with epoxy resins exhibited promising thermal and mechanical performance. Based on these results, biocomposites were also developed by using the protein thermosets as matrices and reinforcing with filling fibers of hemp, woven roving and chopped strand mat glass fibers. Results showed that the biocomposites developed in this research also exhibited promising flexural strength, tensile strength and tensile modulus; despite relatively poor moisture resistance. In another platform, an adhesive for engineered wood composites such as oriented strand board, was developed from the hydrolyzed material. The performance of the engineered wood with the use of the protein based adhesive was evaluated against a commercial adhesive and a standard. In summary, this study has showed that using the knowledge of polymer chemistry and material science, the otherwise hazardous waste SRM can be valorized into a feedstock for a range of useful applications including bio-based plastics, adhesives, biocomposites etc. This approach avoids the cost of landfilling, perceived competition of biomass feedstock with food production while at the same time producing an alternative income source for the rendering and livestock industries.