Colloids and Surfaces A: Physicochem. Eng. Aspects 418 (2013) 7–15 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects journal homepage: www.elsevier.com/locate/colsurfa Effect of physical adhesion on mechanical behaviour of bamboo fibre reinforced thermoplastic composites C.A. Fuentes a,∗ , L.Q.N. Tran a , M. Van Hellemont b , V. Janssens a , C. Dupont-Gillain c , A.W. Van Vuure a , I. Verpoest a a Department of Metallurgy and Materials Engineering (MTM), Katholieke Universiteit Leuven; Leuven, Belgium b Unit Matter, GROUP T - Leuven Engineering College; Leuven, Belgium c Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain; Louvain-la-Neuve, Belgium highlights ◮ The wetting of bamboo fibres con- forms well to the molecular-kinetic theory (MKT). ◮ Meaningful information on the inter- facial interactions was obtained. ◮ X-ray photoelectron spectroscopy analysis was consistent with wetting measurements. ◮ Surface energy components of bamboo fibres and matrices were matched. ◮ Physical adhesion was improved as revealed by pull-out and three point bending tests. graphical abstract article info Article history: Received 24 September 2012 Received in revised form 7 November 2012 Accepted 7 November 2012 Available online 16 November 2012 Keywords: Interface Wetting Fibre-matrix bond Photoelectron spectroscopy (XPS) Bamboo Natural fibre composites Molecular kinetic theory 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 the- oretical 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 compo- nents 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. © 2012 Elsevier B.V. All rights reserved. ∗ Corresponding author. Tel. +32 16 321448; fax +32 16 321990 E-mail address: Carlos.Fuentes@mtm.kuleuven.be (C.A. Fuentes). 1. Introduction The interaction between the reinforcing fibre and the matrix has a significant effect on the properties of the composite since the stress transfer and the load distribution efficiency at the interface is determined by the degree of adhesion between the components. 0927-7757/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.colsurfa.2012.11.018