Study on the compatible interface of bamboo fiber/polylactic acid composites by in-situ solid phase grafting

The in-situ reactive interfacial compatibilization and properties of polylactic acid-g-bamboo fiber (PLA-g-BF)/polylactic acid (PLA) composites, produced by blending with a three-component plasticizer, glycerol/formamide/tributyl citrate, were investigated. The PLA-g-BF/PLA composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and rotational rheometer, and the bending, tensile, and water resistance properties were also tested. The bending strength and elongation at break of PLA-g-BF/PLA composite reached 35.6 MPa and 5.59%, which increased by 19.3% and 30.1% relative to the ungrafted composites. The initial contact angle of the PLA-g-BF/PLA composite was 74.3°, which was larger than that of the ungrafted composite (41.2°), and the water absorption ratio reached 4.3% after 24 h, which was less than the unmodified material (6.1%). SEM results showed that PLA matrix showed smooth surfaces and the interfacial adhesion between modified BF and matrix PLA was greatly improved after grafting modification. The crystal structure results proved that the grafting treatment of BF strengthened the interfacial interactions between the filler BF and matrix PLA, and reduced the mobility of PLA molecular chain. The rotational rheometer illustrated that the initial storage modulus of PLA-g-BF/PLA composites was the largest and decreased slowly, which improved the processing properties of composites.