Environment‐influenced surface layer in polymers

Several epoxy polymers, poly(methyl methacrylate), a highly plasticized polyethylene, and a polyethylene of molecular weight 2500 were found to be influenced to a considerable depth from the surface by the mold material or the atmospheric environment. The results presented are interpreted in terms of a diffuse double layer induced by the mold in the polymer surface region. These environmental effects appear to be greatest for the epoxy systems and are evident to a lesser extent, progressively, as the molded polymer is changed to materials of higher purity or narrower molecular weight range.