Hydrolysis behaviors of ramie fiber/polylactic acid composites under different pH conditions

By using bio-based resin polylactic acid as matrix and plant fiber ramie as reinforcing agent, ramie fiber/polylactic acid (RF/PLA) composites were prepared by melting mixing method. The hydrolysis behaviors of RF/PLA composites in different pH environments were investigated and its degradable properties were evaluated by mechanical properties testing, SEM, DSC and Vicat softening temperature measurement. The results indicate that RF/PLA composites degrade faster in alkaline (pH=12.0) environment than in acid (pH=2.0) or neutral (pH=7.0) environments. The performance deterioration is mainly because the erosion and cavitation of the interface. The addition of RF improves the crystallinity and the Vicat softening temperature of PLA, and accelerates the degradation velocity of PLA. Then the degradation leads to the decline of the mechanical strength of the material. The crystallinity and Vicat softening temperature of RF/PLA composites show a gradual descending with the aggravating of degradation due to the generation of defect in the material. But the crystallinity of pure PLA resin increases and the Vicat softening temperature changes slightly along with the extension of alkali solution treatment time.