Study of the glass transition, crystallization and melting of ethylene-propylene elastomers

Zorina, N.M.; Bukhina, M.F.; Voloshin, V. N.; Rudenko, G.A.; Kotova, I.P.

doi:10.1016/0032-3950(89)90069-5

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…However, samples exposed to lower temperatures (-10 to -50 °C) for 24 hours show endotherms on reheating, suggesting the melting of some crystallinity induced during low temperature exposure in the DSC. This effect is similar to that reported by Zorina et al in ethylene-propylene elastomers [28,42].…”

Section: Dsc -The Effect Of Isothermal Holding Temperaturesupporting

confidence: 92%

The low temperature crystallization of hydrogenated nitrile butadiene rubber (HNBR)

et al. 2018

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Section: Dsc -The Effect Of Isothermal Holding Temperaturesupporting

confidence: 92%

The low temperature crystallization of hydrogenated nitrile butadiene rubber (HNBR)

et al. 2018

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Partially crystallized elastomer as a nanocomposite model

Bukhina¹,

Zorina²,

Morozov³

2005

J Eng Phys Thermophys

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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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