Poly(lactic acid)/halloysite nanotube nanocomposites with high impact strength and water barrier properties

Abstract

Poly(lactic acid)/halloysite nanotube nanocomposites containing epoxidized natural rubber were prepared using melt compounding, followed by compression molding. The mechanical properties of the nanocomposites were determined by tensile, flexural, and Charpy impact test. The addition of 15 wt.% epoxidized natural rubber into poly(lactic acid)/halloysite nanocomposites increased the impact strength to about 340%. However, the tensile modulus, flexural modulus, tensile strength, flexural strength, and elongation at break of poly(lactic acid)/halloysite nanotube were decreased in the presence of epoxidized natural rubber. Water absorption tests were performed at three immersion temperatures (i.e. 30, 40, 50℃). The equilibrium water absorption ( Mm), diffusion coefficient ( D), and activation energy ( Ea) of water diffusion of the poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites were determined. The activation energy of poly(lactic acid)/halloysite nanotube was increased from 14.7 to 31.8 kJ/mol by the addition of epoxidized natural rubber. The percentage retention of impact strength of poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites after exposure to water absorption is higher than 80% for the one containing 5 and 10 wt.% epoxidized natural rubber loading.