Dependence of macroscopic properties on the structure of cast nitrileurea-urethane elastomers
The dependence of the macroscopic mechanical properties and their structural features (such as behaviour during dynamically increasing temperature and structure of the brittle fracture surface) on the structure of nitrileurea/urethane elastomers was investigated. To this aim, dicyandiamide was used for the generation of hard segments and oligoesterdiols with varying chemical structure for the generation of soft segments. These oligoesterdiols differed in polarity, chain flexibility and sequence of mers. It was confirmed that the character of the dependence of macroscopic properties and structural features on the molar ratio of soft segments to hard segments (G/S molar ratio) has a universal character and is independent of the chemical structure of the substrates used. This universality comprises occurrence of discontinuities corresponding to the threshold values of G /S molar ratios, namely the values of 2,1 and 0.5. It was also found that the chemical structure of substrates effects only the absolute values of macroscopic properties of elastomers under study and that the addition of an internal coupling agent results in a specific plasticization of elastomers. In the presence of such agent, the absolute values of the mechanical strength decrease, but the abrasion resistance considerably improves, due to the enhancement of soft segments lability (mobility).
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