Study on natural aging properties of bamboo fibers/polylactic acid composites

The interface of bamboo fiber(BF)/polylactic acid(PLA) composites was regulated by hydroxide and isocyanate,BF/PLA composites was prepared by injection molding process.Natural aging properties of BF/PLA composites was studied by the methods of Fourier transform infrared spectroscopy,X-ray diffraction,gel permeation chromatography and scanning electron microscopy.The results showed that with the synergistic effect of the water,light,heat and oxygen,the PLA molecules in the composites were continuously hydrolyzed,the molecular chains were fractured,the molecular weight was decreased,the certain crystalline state of PLA was gradually transformed into the amorphous state,the degree of crystallinity was reduced,PLA strength was decreased,the bond strength between PLA and BF was continuously decreased,the bonding interface between the two materials was destroyed,the mass of composites reduced and the mechanical properties of composites decreased in the process of natural aging.There are obviously cracks in the surface of composites,and the tensile strength and impact strength were reduced by 69.6% and 75.8% after aging for 137 days.The natural aging of BF/PLA composites was serious and need to adopt certain technical means to further improve the composites outdoor use performance.