Poly (Lactic Acid) (PLA)/Recycled Styrene Butadiene Rubber (rSBR) Composites

Abstract

Recycled styrene butadiene rubber (rSBR) from waste car tires was used as a filler in poly(lactic) acid (PLA) to modify its properties. The compounds were prepared via twin-screw extrusion and molded by injection with different rSBR contents (0 to 25% wt.). Additionally, recycled rubber particle size was controlled between 125 and 1000 μm to determine the effect of this parameter. From the samples produced, a series of morphological, physical and mechanical characterizations were performed. As expected, rSBR addition decreased the PLA stiffness. Up to 5% rSBR, the flexural and elastic moduli were unchanged, but the tensile strength, elongation at break and impact toughness were decreased. The highest tensile strength, elongation at break and impact toughness were achieved for PLA/rSBR blends filled with small rubber particles (125-250 μm). According to the morphological analysis, this behavior was associated to better interfacial interactions between smaller rSBR particles (higher specific surface area) and PLA resulting in a more uniform filler distribution and better stress transfer from PLA to rSBR. Finally, to complete the mechanical properties of the materials, fatigue tests were carried out on different blends and the results were related to instrumented indentation to get some more local information.