Toughening Polylactic Acid with Epoxidized Natural Rubber via Altering the Dicumyl Peroxide Mixing Sequence

The effect of the sequence to add dicumyl peroxide (DCP) to the polylactic acid (PLA) and epoxidized natural rubber (ENR) blending was investigated. According to the tensile and impact resistance tests, premixing DCP with ENR resulted in blends with better mechanical properties where nearly 20 times improvement of impact strength was observed at 30wt% ENR. In addition, the chemical, morphological, and thermal properties of PLA/ENR blends were investigated via Fourier-transform infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry analysis, respectively. When DCP is premixed with ENR, DCP could act more effectively as a vulcanizing agent than a compatibilizer, whereas the DCP mixing with PLA/ENR blending of PLA/ENR might lead to more PLA chain scission than DCP premixing with ENR. This study indicated that the toughening of PLA/ENR blends can be significantly enhanced when high ENR vulcanization together with the formation of small PLA phases.