Tailoring the performance of poly(lactic acid)-based reactive blends: The effect of vinyl acetate and dicumyl peroxide content

Poly(lactic acid) has been gaining prominence in academia and industry, mainly due to being a biopolymer and biodegradable material. Nevertheless, mainly due to its high fragility, work has been carried out in order to seek alternatives to improve this drawback. Hence, this work aims to evaluate the effect of the vinyl acetate content using two types of EVA (EVA(1) with 28% and EVA(2) with 19%) in dynamically vulcanized PLA/EVA blends, using several dicumyl peroxide (DCP) contents, that is, 0.3, 0.5, and 0.7 phr. Blends were produced using an internal mixer, and the tensile, impact and HDT specimens were injection molded. By FTIR and torque rheometry, it was verified that, upon DCP addition, there was evidences of reticulation, resulting in crosslinked PLA, crosslinked EVA, as well as PLA-g-EVA. Through tensile and impact strength tests, it was observed substantial increases in the elongation at break, and in impact strength, mainly for the compounds with higher content of vinyl acetate (EVA(1)). Impact specimens made with PLA/EVA(1)20 0.7 DCP, PLA/EVA(1)30 0.5 DCP, and 0.7 DCP, did not completely break, due to the probable development of the in situ PLA-g-EVA compatibilizer among the present phases. Therefore, it is believed that a more homogeneous microstructure was obtained, as observed by SEM images, highlighted upon the DCP content increase. It was verified that the highest vinyl acetate content is of paramount importance for obtaining PLA/EVA blends with better compatibility as well as EVA(1) being more susceptible to crosslinking using DCP, resulting in blends with greater toughness.

Automated summary

Poly(lactic acid) is gaining popularity in academia and industry due to its biopolymer and biodegradable nature. However, its high fragility has led to efforts to find alternatives to improve this drawback.