Data on the influence of crystallization on the mechanical properties of elastomers -the elastic modulus, the relaxation properties, in particular, restorability in compression, and the tensile strength -have been generalized. These data have been compared to those on the influence of active fillers and a much higher crystallization efficiency has been shown. The size of single crystals has been evaluated for most crystallizable rubbers. It has been inferred that the nanosize of single crystals of elastomers and their direct bond with the elastomer matrix influence the mechanical properties of elastomer materials. In considering a partially crystallized elastomer as a nanocomposite model, one can formulate requirements imposed on efficient nanofillers for elastomer materials.Recent years have been seen an increasing number of works showing the efficiency of the presence of nanosize particles in polymers. At the same time, it is well known how efficiently the mechanical properties of elastomers change in the presence of the crystalline phase. As early as the 1940s, Aleksandrov and Lazurkin [1] and then Treloar [2] clearly substantiated an analogy between the influence of crystallization and filling. However, the reasons for the higher crystallization efficiency are still not clearly understood. The present report seeks to generalize data on the difference in the influence of crystallization and filling on the mechanical properties of elastomers, to analyze the role of the size of crystallites and to compare this role to the role of the size of filler particles, and to make an attempt at formulating requirements imposed on fillers (meeting these requirements improves the efficiency of fillers).Crystallization of elastomers has been studied quite adequately. Its influence on the mechanical properties of elastomers is also known [3][4][5]. Experiments have shown that an increase in the degree of crystallization C to 30% leads to an increase of three orders of magnitude in the elastic modulus of unvulcanized crystallized natural rubber (NR). Figure 1 gives data on a change of more than 1.5 orders of magnitude in the modulus of unvulcanized NR in the process of crystallization to 21% [3, 6]. (Here, apparently, the initial values of the modulus are somewhat overstated, since the initial crystallization (that before the beginning of measurements) is disregarded; this crystallization virtually does not influence the results of measurements of changes in the volume). In the case of polychloroprene (PCP), whose maximum degree of crystallization amounted to 10%, a growth of the order of magnitude in the shear modulus was observed (Fig. 2) [3,7,8]. The tensile [2] and torsional [9] moduli change in the process of crystallization in the same manner. Addition of the most active filler to the rubber, even in dosages at the compatibility level, cannot ensure such an effect.The addition of a filler in the amount C 1 = 5% virtually does not change the mechanical properties, whereas the presence of a 5% crystallization leads to a tw...

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BNKS paraffinate butadiene-acrylonitrile rubbers (ref. 1) are currently the main type of oil-and petrol-resistant rubbers used in the Russian rubber industry. These rubbers contain insoluble calcium paraffinates. The cold resistance of rubbers compounds based on BNKS is lower in a number of cases than that of compounds based on previously produced SKN butadiene-acrylonitrile rubbers. The aim of the present work was to clarify the reasons for this by investigating the lowtemperature and thermophysical properties of BNKS and SKN rubbers and compounds based on them. The investigation was carried out on BNKS rubber (36 specimens), SKN rubber (3 specimens), and Nipol rubber (2 specimens) with a acrylic acid nitrile (AAN) content of 15.0-21.4 and 25.5-33.5%, and also standard and model compounds based on them. The thermophysical properties at temperatures ranging from-130 to +130°C were studied by means of differential scanning calorimetry (DSC); the results obtained are present in the form of thermograms (the dependence of the heat flux dQ/dt on the scanning temperature). Scanning (heating) was carried out at a rate of 40 K/min. The production of thermograms was preceded by the cooling of specimens at a rate of 320 K/min; in some cases, before cooling, the specimens were preheated at various temperatures. Before the tests, all the specimens were held at room temperature for at least 5 days. The thermograms were used to determine the glass transition temperature T g as the start of the sudden change in specific heat (or dQ/dt) on glass transition, the The authors are in the Scientific Research Institute for Elastomeric Materials and Products (NIIEMI) Open Joint Stock Company, Moscow