Chain extension and oxidation stabilization of Triphenyl Phosphite (TPP) in PLA

PLA, which is synthesized from natural resource, has good mechanical property and biodegradable ability, so it is well recognized as a reasonable substituent of petroleum base plastic. Triphenyl Phosphite can increase the molecular weight of PLA through the chain extension with PLA in the melt processing. In this paper, the factors that influence the chain extension of TPP in PLA were studied in detail. The results show that the adding amount of TPP, processing temperature and processing time affect the chain extension of TPP in PLA. When the adding amount of TPP is about 2wt% compared to PLA, the melt temperature is 180 °C and the melt time lasts 15 min, the chain extension is the best. On the conditions, the molecular weight of PLA increases about 56% compared to virgin PLA and can reach 2.52 × 105 g/mol. Furthermore, the chain extension makes the activation energy of oxidation degradation of PLA increases by 14.3%, so the chain extended PLA named PLA-TPP indicates the better oxidation stability.