Effect of silica particle size on the microstructure and physical properties of microporous poly(L-lactic acid) produced by uniaxial stretching

Abstract

Abstract The microporous poly( l -lactic acid) (PLLA) materials were prepared by uniaxial stretching PLLA/20 wt% silica (SiO2) composites. The SiO2 fillers with particle size of 15 nm, 200 nm, 500 nm, 1 μm, 2 μm, and 5 μm were selected to investigate the effect of particle size of fillers on the microstructures and physical properties of the microporous PLLA materials. Micropores were formed due to the debonding at the interface between PLLA and SiO2. The composites with SiO2 particle size of 15 nm, 200 nm, 500 nm, 1 μm, 2 μm, and 5 μm began to debond at 1.4, 1.0, 1.0, 1.0, 0.9, and 0.7, respectively. With the increase of SiO2 particle size, the micropore diameter was enlarged at the same stretching ratio, while the particle number of SiO2 was decreased, however, the porosity was still increased. The mechanical properties, thermal insulation properties, and water vapor permeation properties of microporous PLLA samples were all improved compared with that of undrawn PLLA.