Halloysite nanotubes grafted polylactic acid and its composites with enhanced interfacial compatibility

Polylactic acid (PLA) polymers are promising substitutes for polluting fossil fuel-derived polymers in the field of food safety due to their environmental friendliness, good biocompatibility, and degradability. However, their poor mechanical property limits their practical utilization. In this study, abundant natural halloysite nanotubes (HNTs) were incorporated into PLA to address these issues. To overcome interfacial incompatibility between the matrix (PLA) and nanofillers (HNTs), 3-Aminopropyltrimethoxysilane (APS) were firstly grafted onto HNTs to form end-up amino groups which were served as binding sites for the polycondensation of lactic acid precursors. This formed PLA modified HNTs (pHNTs) precursor was further mixed with bulk PLA polymers to prepare the composite films by the solvent casting method. Compared with the pristine composite, the PLA/pHNTs composites show better thermal stability and mechanical properties, and the composite with 2 wt% pHNTs exhibits the best performance.