Influence of surface treatments on structural and mechanical properties of bamboo fiber-reinforced poly(lactic acid) biocomposites

Abstract

Bamboo fiber-reinforced polylactic acid (PLA) composites were prepared using a film-stacking process. Bamboo fibers were treated using three different methods, i.e., direct silane coupling (DC), silane coupling after plasma (CAP) treatment, and silane coupling during UV irradiation (CDU), to improve the interfacial bonding strength between fibers and PLA. After surface treatment, the chemical group on the surface of bamboo fibers was analyzed through Fourier transform infrared spectroscopy. The intensity of bands around 880–900 cm−1 increased strongly. These results suggested that the grafting of silane onto fibers was enhanced substantially. X-ray diffraction analysis indicated that the amorphous region of the CDU- and CAP-treated fibers increased. The interfacial shear strength between the fibers and the matrix also increased by 44.2%, 64.2%, and 87.4% by DC, CDU, and CAP treatment, respectively. In addition, the tensile strength of bamboo–PLA composites with DC-, CDU-, and CAP-treated fibers increased 43.0%, 61.1%, and 71.2%, respectively. Moreover, the predicted tensile modulus of the composites with CAP-treated fibers showed good agreement with the experimental one.