Thermal and mechanical properties of aminolyzed‐poly(lactic acid) with amine‐terminated dendritic polymer: Surface and bulk functionalization

Abstract

This study details the effect of surface and bulk functionalization of poly(lactic acid) (PLA) with an amine‐terminated dendritic polymer, poly(amidoamine) (PAMAM), on the thermal and mechanical properties of PLA‐based formulations. Fourier‐transform infrared spectroscopy (FTIR) confirmed the presence of –NH2 groups derived from PAMAM, through emerging new peaks at around 1650 cm−1 associated with –NH bending vibration and separate double peak between 3705 and 3110 cm−1 associated with stretching vibration of –NH amide groups, in both surface and bulk functionalized PLA samples. Differential scanning calorimetry (DSC) measurements revealed a lowering of cold‐crystallization temperature (Tcc) for both surface and bulk functionalized PLA, suggesting that PAMAM served as a nucleating agent. According to thermogravimetric results (TGA), bulk treatment deteriorated the thermal stability of the polymer; while surface modification did not influence the decomposition pathway. Mechanical test results revealed that PAMAM greatly influenced the stiffens and ductility of the composites, with more pronounced changes for higher aminolysis rates. Therefore, the 3‐h PAMAM surface functionalization of PLA limits its affinity to solvents' content and enhances crystallization upon permissible deterioration in mechanical properties.Highlights Development of aminolyzed‐PLA by surface and bulk modification with PAMAM dendritic polymer. PAMAM as a nucleating agent for PLA. Surface modification as the favorable condition to introduce NH2 groups to PLA.