Effect of physical adhesion on mechanical behaviour of bamboo fibre reinforced thermoplastic composites

Abstract

Systematic experimental results describing the dynamic wetting properties of bamboo fibres were analysed by applying the molecular-kinetic theory of wetting. Results suggest that the bamboo fibre surface represents a well-defined system for wetting analysis. The surface free energy components were calculated according to the acid–base theory. These values were then used to calculate the theoretical work of adhesion, spreading coefficient, wetting tension, and interfacial energy. The wetting behaviour of various thermoplastic matrices (polypropylene, maleic anhydride-grafted polypropylene, polyvinylidene-fluoride, and polyethylene-terephthalate) was characterized. Surface chemical components were identified using XPS. Additionally, transverse 3-point bending tests and single fibre pull-out tests were performed. This integrated physical–chemical–mechanical approach was used to study the effect of adhesion on the mechanical strength of thermoplastic composites reinforced with bamboo, showing that increase in physical adhesion can explain the improved interfacial and longitudinal strength in bamboo polyvinylidene-fluoride (PVDF) composites compared to the other thermoplastic matrices used in this study. Surface energy components of bamboo fibres and PVDF were matched, resulting in an improvement of the physical adhesion.