Methods for surface activation of wood-fiber reinforced thermoplastic composites for surface adhesion enhancement and composites having such surface properties

A method for treating the surface of a wood plastic composite material to enhance its surface adhesion properties to a water-based acrylic coating material, the method comprising the use of at least one of the following surface activation methods:

• i) oxygen plasma treatment to increase a wettability of the wood plastic composite material with polar liquids, wherein the oxygen plasma treatment includes exposing the wood plastic composite material to a oxygen plasma for a predetermined time exposure;
• ii) flame treatment for increasing an acrylic coating peel load, wherein the flame treatment includes exposing the wood composite material to a flame at a predetermined distance from the flame;
• iii) chromic acid treatment for roughening of a surface of the wood plastic composite material, wherein the chromic acid treatment includes applying a chromic acid solution to the surface of the wood plastic composite material;
• and
• iv) benzophenone/UV irradiation (BP/UV) treatment for increasing an acrylic coating peel load, wherein the BP/UV treatment includes immersing the wood plastic composite material in a benzophenone-solvent solution, evaporating the solvent, and UV irradiating the wood plastic composite material.