Surface treatment of wood polymer composites for adhesive bonding

An experimental study was undertaken to evaluate different surface treatment techniques for adhesive bonding of a Wood Polymer Composite (WPC) material. The surface treatment methods were flame, corona discharge treatment (CDT), mechanical abrasion (MA) and combination treatment of MA followed by the CDT. Surface analytical techniques used were contact angle analysis, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Atomic Force Microscopy (AFM) and 2 dimensional profilometry. Adhesion pull-off test was used to assess the effects of surface treatments. The combination surface treatment, i.e. MA+CDT, was particularly effective in improving bonded joint strength. The adhesion pull-off strengths increased from 0.2 MPa for untreated substrate to 3.4 MPa for MA+CDT treated substrates. The carbonyl, hyroxyl and wood indices obtained from the ATR-FTIR spectra were valuable indicators for studying the nature of WPC substrates.