A wood bioplastic composite from soy flour and sawdust: influence of process parameters and composition on physical and mechanical properties

Abstract

The influence of the processing conditions and composition on the properties of biocomposites made of a bioplastic matrix from soybean protein, crosslinked with glutaraldehyde, reinforced with lignocellulosic material from wood sawdust (Wood Bio-Plastic Composite, WBPC) was investigated. The WBPCs were obtained by thermocompression applying a pressure of 70 bar at 100 and 120 °C for 30 or 60 minutes. Several test pieces were prepared varying the crosslinker/protein and protein/sawdust ratios. The samples obtained were characterized by scanning electron microscopy (SEM), flexural and hardness tests, and water absorption and swelling, according to international ASTM standards. The crosslinking of the protein improves the mechanical properties of the biocomposites, especially when contents of bioplastic matrix and crosslinker are low. It was also verified that the WBPCs prepared in this work recover their original shape and dimensions after immersion in water and subsequent drying. The results were explained considering crosslinker-protein and protein-sawdust interactions.