SURFACE-ANALYSIS OF POLYMERIC JOINTS

The stability of polymer-to-polymer joints was assessed using a thermo dynamic method based on surface tension components, similar to that de veloped by Kinloch et al.,1 showing that joint stability is improved i n air by plasma treatments, while it is depressed in water. Shear stre ngth tests showed qualitative agreements with these suggestions. Surfa ce analysis by contact angle measurements, SSIMS and XPS allowed the c larification of contributions which originated from phenomena unaccoun ted for by thermodynamic analysis. Plasma treatment was shown to form a weak boundary layer on polypropylene surfaces, possibly due to depol ymerization. In the case of polycarbonate a water sensitive, possibly water soluble, layer is formed, therefore inducing a remarkable decrea se in shear strength upon immersion in water.