Degraded rubber vulcanizates swollen in benzene was cooled, and the degree of freezing point depression of the benzene, ΔT, was determined. This measurement is generally called a cryoscopic method. It was experimentally found that the relationship between ΔT and the average radius of gyration of network chains, RG, which characterizes mesh size of network in swollen crosslinked rubber, can be given by the following equation : ΔT-R_G^m
The above relation is the same as those of an undegraded rubber vulcanizates, except for the numerical coefficient. The exponent m of degraded networks was larger than that of undegraded ones. ΔT increases due to smaller meshes remaining in degraded networks, even if the crosslink density of a degraded sample is equal to that of an undegraded one. Meshes of various size exist in degraded networks and the distribution of mesh size occurs, which is influenced by degradation conditions and/or degradation mechanism, and the exponent m can reflect the inhomogeneity of degraded network structure. Such the inhomogeneity can be detected only by a cryoscopic method, but not by the conventional technique such as stress-strain measurement and the swelling method.

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A series of composites were prepared using commercial polymers, mostly Nylon 12, and various chatter-machined metal fibers (aluminum, copper, steel and brass) and carbon fiber to provide shielding materials for electromagnetic interference, and the thermal stability of the electrical conductivity and the shielding effectiveness (SE) of the composites were examined at 80°C in air. The order of the generation of the SE was, copper > brass > aluminum > steel > carbon, and except carbon fiber series all composites showed deterioration of the SE during the thermal treatment. In the aluminum series, the thermal stability was improved remarkably by the surface treatment of the fillers with commercial polymers and oligomer solutions or their solvents. The thermal stability of the SE of the composites was discussed taking account of the physical properties of the matrix polymers.

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