Toughness Improvement in Bio-based Poly(Lactic Acid)/Epoxidized Natural Rubber Blend Reinforced with Nanosized Silica

This study focused on improving the toughness properties of poly(lactic acid) (PLA) by blending with either epoxidized natural rubber (ENR) or ENR plus nanosized silica (nSiO(2)). ENR with 30 mol% epoxidation (ENR-30) was synthesized via in situ performic acid epoxidation of NR latex under a controlled amount of hydrogen peroxide and formic acid. PLA was melt-mixed with three weight percentages (10-30 wt %) of ENR-30 using an internal mixer, followed by compression molding. The 80/20 PLA/ENR-30 blend showed the highest impact strength and elongation at break, indicating the optimally possible improvement in the toughness of PLA. This composition was further chosen for fabricating nanocomposites with nSiO(2) at 1-3 phr. Nanocomposite at 2 phr nSiO(2) revealed the highest impact strength with 1.8-fold over the neat blend, but the tensile properties of all nanocomposites decreased with the increasing nSiO(2) contents. The scanning electron microscopy analysis showed a preferential distribution of nSiO(2) in the ENR-30 phase rather than in the PLA phase. Based on thermal analysis results, the thermal stability of the entire nanocomposites was significantly higher than that of the neat blend, while the thermal behavior (T-g and T-m) of PLA in the nanocomposites showed no significant change. [GRAPHICS] .