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Surface tension of polymer mixtures and copolymers

1974; Wiley; Volume: 12; Issue: 6 Linguagem: Inglês

10.1002/pol.1974.180120614

1542-9385

Andor Schwarcz,

Adhesion, Friction, and Surface Interactions

Abstract Contact angles θ of liquids of different polarity were measured on a series of mixtures of solid high polymers and a series of copolymers. The mixtures were composed of an alternating poly(ethylene‐ co ‐maleic anhydride) (EMA), and its addition product with n ‐octadecylamine, poly(ethylene‐ co ‐ N ‐ n ‐octadecylmaleamic acid) (EOM). The co‐polymers were composed of the same monomeric units as the mixtures. The surface tension γ s of EOM, calculated from θ by the Good‐Fowkes‐Owens‐Wendt treatment, decreased slightly with increasing molecular weights and then reached a limiting value. Plots of γ s against EOM concentration indicated large negative excess surface tension of the units with lower surface tension, EOM, in both series studied. For the mixture series, γ a first sharply decreased with the EOM concentration; then it reached a limiting value, the γ s of pure EOM, at a very low EOM concentration. This indicates phase separation of the two polymers, and the thickness of a monomolecular surface layer was calculated from these data. For the copolymers, γ s varied logarithmically with the EOM concentration. Throughout the whole concentration range, the data fitted the equation developed by Belton and Evans for ideal mixtures.