Preparation and properties of silane-treated banana fiber/poly(lactic acid) biocomposites

Abstract

Poly(lactic acid) (PLA) reinforced with silane-treated banana fiber (BFSi) at various fiber contents was studied. Banana fiber surfaces were firstly treated by sodium hydroxide and subsequently by 3-aminopropyl triethoxysilane. The biocomposites were then prepared by melt blending method in a twin-screw extruder. The effect of BFSi fiber contents on the mechanical and thermal properties of the biocomposites were investigated. Scanning electron microscope (SEM) was used to reveal the cryo-fractured surfaces of the composites. Mechanical properties, thermal characteristics and thermal stability were carried out by universal testing machine, differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), respectively. Interfacial adhesion between PLA matrix and BFSi fibers was significantly improved even fiber content up to 40% by weight. There were few fiber pull-outs or voids appeared. With increasing fiber contents, tensile modulus and strength increased while elongation at break decreased. Moreover, glass transition temperature (Tg) and cold crystallization temperature (Tcc) decreased, whereas, crystallinity (Xc) significantly increased, however, melting temperature (Tm) was almost intact when fiber contents increased. The composites with higher amount of fibers exhibited faster thermal decomposition and higher residue contents at 550°C.