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synopsisThe activity of Schiffs bases of cinnamic aldehyde and aromatic amines in the controlled photodegradation of polyethylene (PE) was studied. N-cinnamylidene anilines containing different substituents in the amine ring (methyl group, halogen, or amine group) and N-cinnamylidene a-naphthyl amine were synthesized and introduced into the polyethylene films by compression molding or extrusion, and they were exposed to the filtered ultraviolet light produced by mercury lamp. The changes in molecular weight, tensile strength, and characteristic IR absorptions were followed during irradiation to control the processes undergoing in the polymer films. It was discovered that N-cinnamylidene anilines containing methyl or halogen substituents and N-cinnamylidene a-naphthyl amine accelerated the photodegradation of polyethylene. Their sensitizing activity increased when the mixtures of Schiffs bases and stannous laurate were introduced into the polymer. PE films containing these additives became brittle after 600 h exposure to the artificial UV light which was the equivalent of 1.5-2 years exposure to the natural sunlight in the medium geographic latitudes. The mechanism of the initial step of photodegradation is discussed.

SynopsisIt was expected that elemental copper or zinc introduced into polycaproamide would interact with amide groups of the polymer and that the materials would be characterized by semiconductor properties. To prove this theory, resistivity at several temperatures was determined and thermal activation energies calculated. As the metal contents were relatively low, metallic conductivity was avoided. Temperature-resistivity dependence and a negative temperature coefficient of the resistivity prove that polyamide-metal compositions can be classified as semiconductors.

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