SURFACE TREATMENT AND ADHESION OF POLYMER FILMS

摘要

The surface of polyolefins such as polyethylene and polypropylene has very poor polarity. The distribution of electron charge densities in polyethylene was calculated by molecular orbital method and the difference between carbon and hydrogen is very small, as shown in Fig.1. Dispersion force only gives rise to attraction between molecules and is too weak for adhesion. It is generally believed that adhesion is mainly attained not by covalent bonding but by molecular-molecular interactions, i.e., permanent dipole. Therefore, the localization in electron charge densities is very important in adhesion. The introduction of functional groups having high polarity is required for attaining sufficient adhesion. The oxygen containing functional groups is easy to introduce to polymer molecular chains, though various kinds of functional groups are possible to introduce in principle.