Torrefied biomass filled polyamide biocomposites: mechanical and physical property analysis

Biobased fillers in thermoplastics have seen increased usage over the last several years. The increased usage of biobased fillers follows the ever-increasing thrust to reduce petroleum and synthetic petrochemical product consumption. The study of polyolefin-based biocomposites is well established, however, the incorporation of biomass fillers into engineering thermoplastics still proves to be challenging. For engineering thermoplastics, the increased processing temperatures lead to degradation of the biomass, often detrimental for the mechanical performance and visual appearance of the end product. The goal of this work was to evaluate the effectiveness of agricultural by-products as fillers in polyamides, while minimizing the effects of increased processing temperatures. Through the use of torrefaction, polyamide biocomposites were produced and shown to have comparable mechanical properties to the neat matrix. Torrefied sunflower hulls and flax shive were shown to produce tensile strengths within 70 % of the neat matrix, increase elastic modulus by 150 %, maintain flexural strengths within 94 % of the neat matrix, increase flexural modulus by 154 %, and decrease the absorption of environmental moisture by as much as 50 %.