Moisture Absorption and Thermal Properties of Unidirectional Pineapple Leaf Fibre/Polylactic Acid Composites under Hygrothermal Ageing Conditions

Abstract

In this study, the effect of fibre content on moisture absorption and thermal properties of pineapple leaf fibre (PALF) reinforced polylactic acid (PLA) at elevated temperature and humidity was assessed. The unidirectional PALF/PLA composites were fabricated by using pre-pregging technique and compressed moulded to produce composites with two fibre loadings (40 and 60 wt. %). The composite was saturated in a humidity chamber that contains 90% relative humidity at 50°C for 30 days. The effect of different fibre loading on moisture absorption was measured through moisture uptake. Their thermal stability and thermal characteristic were evaluated by using thermal gravimetric analysis (TGA) and differential scanning analysis (DSC). The result showed that moisture absorption increases with the increase of fibre content and follows Fickian Law. The presence of PALF reduces the initial thermal degradation of the neat PLA as well as promoted the crystallization of the PLA.  Upon exposure to the high temperature and humidity, the value glass transition temperature (Tg) and melting temperature (Tm) of the neat PLA and PALF/PLA composites shifted to the lower temperature possibly due to hydrolytic degradation in the composite structure.