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W. M. Rzymski, B. Wolska

Physical structure and topology of elastomers networks

Polimery 2003, No 4, 246


Summary

Two groups of chosen models of elastomers networks have been discussed on the basis of literature data and own research results. The first group of models encloses: statistical theory of elasticity, Mooney-Rivlin model, model with constraints on chain and junctions, tube model by Heinrich, Straube and Helmis as well as Tschoegl model. They use simple experimental measurements of stress - strain dependence. However the concentration of chemical crosslinking joints of network, Nc, and crosslinking efficiency Ec, calculated for NR and IR cured with dicumyl peroxide (DCP) are much higher than the values resulting from the known mechanism of these elastomers curing with a peroxide (Ect = 2) (Table 1, Figs. 3 and 4). In the second groups of models, by Charlesby-Pinner (concerning the rubber showing Mw/Mn ≈ 2) and by Langley and Pearson (any value of Mw/Mn), there is necessary (for proper analysis) to do labour-consuming determinations of sol content as well as molecular weight and polydispersity of a rubber before curing, but this way determinated values of Nc and Ec, in case of curing NR and IR with DCP [(Ec = 1.8-2.0), agree with theoretical values (Table 1)]. These methods can be recommended to complex analysis of physical structure and topology of a network. In networks of cured elastomers there are both the chemical and permanent topological joints. Their part in total number of network joint reaches up to 80% when chemical crosslinking degree is not high.


Keywords: networks of elastomers, chemical and topological joints, chain entanglement, comparison of network models, crosslinking efficiency


W. M. Rzymski, B. Wolska

Physical structure and topology of elastomers networks