Influence of Chemical Treatments on the Interfacial Properties of Ramie Fiber Reinforced Poly(lactic acid) (PLA) Composites

In this study, effects of chemical treatments on the interfacial properties of ramie fibers and the poly(lactic acid) (PLA) matrix are investigated. Three surface treatments are performed on ramie fibers, namely alkali, silane coupling agent (3-aminopropyltriethoxy silane) and alkali-silane combined treatments. Scanning electron microscopy (SEM) results showed that the alkali-treated fiber seemed to be the cleanest with many characteristic striations on the surface. Fourier transform infrared spectroscopy (FT-IR) analysis indicates that alkylsilane is successfully grafted on the ramie fibers after the silane coupling agent treatment while no chemical composition change occurs for the alkali treated fibers. The surfaces of the alkali-treated fibers with a water contact angle of 38.5 degrees become more hydrophilic compared to the untreated fibers (46.9 degrees) while those of the silane treated fibers become slightly more hydrophobic with a water contact angle of 56.7 degrees. Micro-bond tests show that the interfacial shear strength (IFSS) value of the alkali-silane combined treated fibers and the PLA matrix increases the most by around 40%. In addition, the ramie fiber tensile strength does not change significantly after the chemical treatments.