Characterisation of the Interfacial Adhesion of the Different Components in Wood–Plastic Composites with AFM

Abstract

The search for innovative solutions for the reuse of solid residues has intensified with growing environmental issues and the increasing cost of most raw materials, leading to the design of eco-friendly composite materials, such as wood–plastic composites (WPCs). These materials combine the stability of wood fibres with the durability of plastic, allowing for a wide range of applications, whilst simultaneously offering the possibility of utilising waste products from the forest/wood industry and recycled plastic. Waste products that otherwise incur cost for disposal therefore become a sustainable material resource for new products. Natural fibres offer a number of advantages over synthetic fibres and are seen as a “green” alternative to other reinforcements. Commonly, the fibre-matrix adhesion in WPCs is improved by using compatibilisers that bond to the polar wood fibres and the non-polar polymer matrix. However, the problem with these is that good dispersion is not always achieved as it depends on the adhesion properties of three individual components in the WPC, which might lead to poor mechanical properties of the WPC. The ability of the atomic force microscope (AFM) to create 3D images of topography and various interaction forces with molecular resolution made it a valuable tool for the analysis of adhesion properties in WPCs.