Improvement of thermal and mechanical properties of Poly(L-lactic acid) by blending and radiation-induced crosslinking

Tago, Takanori; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*

Poly (L-lactic acid) (PLA) derived from corn starch is now widespread with a potential to replace the conventional petroleum-derived plastics. The PLA has, however, the less thermal stability above around 60C and impact resistance at room temperature than the conventional plastics. In this study, to improve the above-mentioned two properties of PLA, we investigated a new combination method of blending with polyamide11 (PA11) having high impact resistance, which is derived from castor oil, and then crosslinking. PLA/PA11(50/50wt%) blend with 3 phr of crosslinker irradiated to 100 kGy was formed about 80% of gel content. This sample demonstrated very little deformation above the grass transition-temperature of PLA, the melting-temperature of PLA and PA11 (ca.175C and 185C, respectively) by thermal-mechanical analysis. The impact value of crosslinked PLA/PA11 blend is 4.8 kJ/m. This value showed higher about 2.5 times of original PLA. Therefore, the applications of bioplastics will be expanded.