Effect of nano-SiO2 on the compatibility interface and properties of polylactic acid-grafted-bamboo fiber/polylactic acid composite

To improve the properties of polylactic acid-grafted-bamboo fiber/polylactic acid (PLA-g-BF/PLA) composite, a compatible interface was constructed by adding nano-silica (nano-SiO2). The results showed that, with increased nano-SiO2 mass ratio, the composites' mechanical strength and water resistance were significantly improved. The composite with a 1.5% nano-SiO2 mass ratio exhibited the best mechanical properties and water resistance. Strain scanning results showed that the strain value at which the storage module (G') of the composite began to decrease was the largest with 1.5% nano-SiO2 and the G' and complex viscosity (η*) of the composite also reached the best state at this point. The interfacial compatibility between PLA-g-BF and PLA was also confirmed to be the best at this mass ratio. SEM and TEM analyses indicated that, when the mass ratio of nano-SiO2 was 1.5%, nanoparticles were uniformly dispersed in the composite and PLA-g-BF and PLA in a state of integration. The addition of nano-SiO2 was beneficial for the crystallization and nucleation of PLA, and composite crystallinity with 1.5% nano-SiO2 reached the maximum value. With increased interfacial compatibility and crystallinity of the composite, the thermal stability was also best when the mass ratio of nano-SiO2 was 1.5%.