Exploring the Impact of Dynamic Vulcanization on Ductile-Brittle Transition and Morphology Evolution of PLA/EVA Blends

Blends of poly (lactic acid) (PLA) enhanced with ethylene-vinyl acetate copolymer (EVA) and dynamically vulcanized have garnered interest from researchers and the polymer industry due to their versatility and combined properties. These include the high elasticity of EVA and the environmentally friendly characteristics of PLA, which is both a biopolymer and biodegradable. This study aims to produce PLA/EVA blends dynamically vulcanized with dicumyl peroxide (DCP) and evaluate their rheological, thermal, morphological, and ductile-brittle transition properties. The materials were prepared by melting them in an internal mixer and injection molding them to produce impact test specimens. Rheological analysis showed that the compounds with DCP exhibit increased complex viscosity (eta*), storage modulus (G '), and loss modulus (G ''), indicating the formation of crosslinks and the in situ creation of the PLA-g-EVA copolymer. Morphological analysis revealed improved homogeneity with the addition of DCP, characterized by an interconnected, nearly co-continuous structure, as observed primarily through transmission electron microscopy (TEM). Scanning electron microscopy (SEM) showed that as the temperature decreased, voids appeared on the surface of the PLA/EVA/DCP compounds, reducing impact strength. The ductile-brittle transition temperature for the PLA/EVA/DCP compounds was approximately 17.5 degrees C for compositions with 20% and 30% EVA.