Polylactide compounding for injection molding product

Abstract

The ring-opening polymerization of lactide was synthesized in single step process via using stannous (II) octoate, Sn(Oct)₂ as a catalyst to get the high molecular weight of polylactide (PLA). For improving the thermal and mechanical properties of PLA, the graft copolymerization between a lactide monomer and epoxidized natural rubber (ENR), ENR-g-PLA was synthesized. The ENR-g-PLA copolymers were successfully synthesized and confirmed by FT-IR spectra. The occurrence peak at 1740 cm¯¹ and 3400 cm¯¹ corresponded to the carbonyl group (C=O) and hydroxyl group (-OH) which resulted from the reaction between PLA and ENR. Moreover, the ENR-g-PLA copolymers gave the molecular weight around 1.87 x 10⁴ to 2.78 x 10⁴ g/mol. The highest amount of copolymer and the highest molecular demonstrated at the catalyst content around 0.2 wt% and the temperature of mixing around 160 ºC. Furthermore, the calculation of grafting showed that there was 24%grafting of ENR on PLA. Also, the degree of grafting was directly proportional to various ENR contents. For the thermal properties, the decomposition temperature of copolymer (~355 ºC) was higher than pure PLA (~332 ºC). In addition, the impact strength of copolymer increased in the presence of ENR. The impact strength of ENR-g-PLA increased 1.5-folds in comparison to pure PLA. The elongation of copolymer was improved compared to pure PLA. Moreover, the morphology of copolymer was studied by FE-SEM. The results revealed the well dispersion phase of ENR in PLA matrix.