Water absorption and hygrothermal aging behavior of short ramie fiber‐reinforced poly(lactic acid) composites

Short ramie/poly(lactic acid) (PLA) composites were prepared by using extrusion and injection moulding method. The water absorption and hygrothermal aging behaviors of ramie/PLA composites at 60°C was analyzed. The water absorption and mechanical properties of the ramie/PLA composites with immersion time were reported and compared to those of neat PLA. Crystallinity and molecular weight of neat PLA and ramie/PLA composites were determined by differential scanning calorimetry and gel permeation chromatography, respectively. The results showed that the water absorption and mechanical properties was affected by the short ramie fiber. Ramie/PLA composites showed higher saturation weight gains and diffusion coefficients than that of neat PLA, which indicated that the addition of short ramie fiber induced higher water absorption caused by the hydrophilic nature of the fibers. Tensile strength and flexural strength severely decreased after aging. Moreover, it was found that PLA was severely degraded in hygrothermal environment, and ramie accelerated the degradation of PLA. The morphologies of fractured surfaces of neat PLA and ramie/PLA composites with different immersion time were observed by scanning electronic microscopy. The micro‐cracks and voids were found which was due to the degradation of PLA and debonding of ramie and PLA. POLYM. COMPOS., 39:1098–1104, 2018. © 2016 Society of Plastics Engineers