Physical Properties of Poly(lactic acid)/Hydroxyl Terminated Natural Rubber Blends

Summary The objective of the study is to use hydroxyl‐terminated natural rubber (HTNR) as the toughening modifier for poly(lactic acid) (PLA). Photochemical degradation of natural rubber by ultraviolet radiation from high pressure mercury vapor lamp was used as depolymerization and hydroxylation of natural rubber. Molecular weight of HTNR was 25,000 ( ) and estimation of hydroxyl number of HTNR according to ASTM D4274‐11 was 2.04 mg KOH/g. The present of hydroxyl group was confirmed by FT‐IR, 1 H‐NMR and 13 C‐NMR spectrum. HTNR was blended with PLA in the ratio of 100/0, 100/3, 100/5, 100/10, and 100/15. Tensile and impact tests were carried out according to ASTM D638 and D256 respectively. It was found that tensile strength and tensile modulus of the PLA/HTNR blends were not significantly decreased whereas elongations at break were increased up to about 9 times compared with neat PLA. For impact properties, the results showed that impact strength of PLA was significantly increased up to 4 times with an addition of 10 wt% HTNR. SEM micrographs of the blends showed well disperse of HTNR particles and the occurrence of ductile fracture.