Effect of fibre surface treatment on interfacial and mechanical properties of non-woven kenaf fibre reinforced acrylic based polyester composites

The interfacial and mechanical properties of nonwoven kenaf fibre (KF) reinforced acrylic based polyester composites fabricated by resin impregnation process were studied. Different types of treatments were applied to KF, i.e. alkali treatment with NaOH at concentration of 6% (at room and elevated temperature of 60 degrees C) and heat treatment at 140 degrees C for 10h. FT-IR spectral data showed the chemical changes in KF that induced the modification of physical and interfacial characteristics of KF. Alkali treated KF was found to have smaller diameter but higher density. Significant increase in the crystallinity index of treated KF contributed to the improved fibre strength. AFM analysis revealed the exposure of cellulose micro-fibril network and the increase in the area peak density value of treated KF. Surface energy of KF and surface tension of acrylic resin were obtained through Owens-Wendt-Rabel-Kaelble (OWRK) equation and Du Nouy ring approach, respectively, for the interfacial properties determination. The improved wettability of alkali treated KF was confirmed as higher surface energy of the fibre was recorded exceeding the surface tension of acrylic resin, thereby imparting better flexural properties and dynamic mechanical behavior, but conversely deteriorating the fracture toughness of the reinforced composites. POLYM. COMPOS., 40:E214-E226, 2019. (c) 2017 Society of Plastics Engineers