Effect of Surface Treatment on the Correlation in Non Destructive Testing for Wood Plastic Composites Adhesive Joint

The epoxy resin adhesive was used to bond the polyethylene woodplastic composites (WPC) combined with three treatment methods, including sanding treatment, coupling agent coating and plasma treatment. The correlations between dynamic parameters and shear strength in nondestructive testing for the WPC adhesive joints were measured with the longitudinal vibration method. The results showed that there was no correlation between resonant frequency and the shear strength of the WPC specimens regardless of surface treatment methods. The ratio of resonance frequency before and after bonding had a certain correlation with the bonding strength for the WPC specimens only treated with sanding process. Both dynamic modulus of elasticity and dynamic modulus of elasticity ratio had significant correlations with the shear strength for the WPC specimens coating treated with silane coupling agent, which was better than that for the WPC specimens only treated with sanding process. The dynamic parameters had no obvious correlation with the shear strength for the WPC specimens treated with plasma treatment.