Preparation and characterization of polylactic acid-g-bamboo fiber based on in-situ solid phase polymerization

This study details effort to improve the interfacial compatibility of bamboo fiber/polylactic acid composites, by attaching the molecular chain of polylactic acid (PLA) to bamboo fibers (BF). The BF was pretreated using a 1 wt% sodium hydroxide solution and the lactic acid was then grafted onto BFs using in-situ solid phase polymerization. The prepared PLA grafted BF (PLA-g-BF) was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), the results confirmed that the grafting reaction occurred successful. The grafting ratio of the PLA-g-BF was 16.51% and the degree of substitution was 35.59%. The effect of reaction temperature and time on the degree of substitution of the PLA-g-BF was studied. The results showed that a reaction temperature of 80 °C and a reaction time of 7 h were the optimum conditions. The hydrophobicity, surface morphology, crystal structure, thermal properties and tensile properties of the PLA-g-BF were characterized. The results demonstrated that the surface and interior of BF were covered with PLA. The crystalline structure of the BF was somewhat damaged, which decreased its crystallinity and tensile strength. The grafting reaction improved the thermoplasticity and thermogravimetric performance of the PLA-g-BF. Moreover, the hydrophobicity of the PLA-g-BF was significantly increased.