Mechanical Optimization of Virgin and Recycled Poly(ethylene terephthalate) Biocomposites with Sustainable Biocarbon through a Factorial Design

Abstract A statistical approach was taken to evaluate the effect of using recycled poly(ethylene terephthalate) (RPET), sustainable biocarbon and a chain extender on the performance of impact-modified PET biocomposites. Through a full factorial design, the extrusion-injection molded samples were tested for their tensile and impact properties. The mechanical results of the experiment were analyzed based on how the factors’ main effects and interactions between them varied the properties. The novelty is observed through the combination of the chain extender in the presence of the biocarbon reinforcing filler that enhanced stiffness and tensile strength through a synergistic interaction, while also providing a 278% increase in impact toughness over the biocarbon variant without chain extender. The inclusion of chain extender was the most important factor, with the biocarbon being the second most influential contributor, in causing changes in all mechanical properties measured, partially due to the morphological differences observed. Through this investigation, an optimized biocomposite formulation that had 28% sustainable content, with 10 wt.% biocarbon, 25 wt.% RPET substitution of PET and 1 phr of chain extender, was chosen that maintained a stiffness-toughness balance in the range of the statistical design.