Study of the chemical endurance of particulate reinforced thermoplastic composites

Polylactic acid (PLA) is a biodegradable thermoplastic made from lactic acid monomers obtained through fermented glucose in crops like wheat and corn. PLA has numerous applications, including industrial packaging, biomedical equipment, and membranes, due to its low toxicity, biodegradability, and recycling potential. However, little is known about the short-term aging effects of particulate reinforced PLA composites in complex environments. This study investigates the chemical endurance of various PLA composites before and after exposure to different chemicals and hygrothermal conditions. The results reveal that the fabrication processing method greatly affects the degradation rate. The PLA/Carbon Fiber Powder (CFP) samples had the highest chemical resistance towards degradation in 1% HNO₃ followed by 2% NaOH with a maximum mass increase of 2.8% and 3.9% respectively. The PLA/CFP samples showed lowest chemical resistance under a combination of water and aging temperature, with an average maximum weight gain of 9.64% throughout the three CFP loadings. Continuous test for 15wt% CFP sample under subsequent liquid immersion and hot air exposure had an insignificant mass loss of 0.76% but a very brittle surface with severe micro and macro cracks were present on the sample surface. In conclusion, while PLA/CFP composites demonstrate notable chemical resistance under certain conditions, the short-term aging effects, particularly under hygrothermal conditions, reveal the significance of fabrication processing methods and the potential brittleness induced by continuous exposure to specific environments, emphasizing the need for a comprehensive understanding of material behaviors.