STRESS-STRAIN RELATION AT LOW ELONGATION

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  • Kotani T.
    Department of synthetic oChemistry, Faculty of Engineering, Kyoto University
  • Furukawa J.
    Department of synthetic oChemistry, Faculty of Engineering, Kyoto University
  • Yamashita S.
    Department of synthetic oChemistry, Faculty of Engineering, Kyoto University
  • 古賀 重宏
    京都大学工学部合成化学教室

Bibliographic Information

Other Title
  • 低変形におけるゴムの応力-ひずみ曲線について
  • テイヘンケイ ニ オケル ゴム ノ オウリョク-ヒズミ キョクセン ニ ツイテ
  • STATIC AND DYNAMIC PROPERTIES OF RUBBER (II)

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Abstract

In the previous report*, the equation of the stress-strain relation of rubber vulcanizates at low elongation was shown as<br>f=f0+RT (α-1/α2), (1)<br>where f, f0, R, T and α indicate stress, correction factor, gas constant, absolute temperature and elongation ratio, respectively.<br>In this paper an attempt is made in order to establish a correction factor f0 for each of several rubbers, i.e., natural rubber, emulsion polybutadiene and styrene-butadiene rubbers (SBR) having different styrene contents. Examples of the correction factors obtained from stress-strain curves above α>2 at 0.2cm/min of strain speed were as follows: 0.8kg/cm2 for natural rubber, 1.0kg/cm2 for emulsion polybutadiene, 1.6kg/cm2 for SBR containing 23.5% bound styrene, etc. At a low strain rainging, α<1.5, f0 was not constant and increased with α. If f0 is indica-ed by f2 in the low range, f2/(α-1/α2) was related linearly to exp {-(α-1)}. From these experimental results total stress f is given by<br>f=(ν1+ν2) RT (α-1/α2) (2)<br>ν2=N0 exp{-(α-1)} (3)<br>where ν1 is equal to ν in the equation (1), and ν2, N0, and E indicate the number of crosslinks of secondary bond, the number of segment and cohesion energy, respectively. The term of exp {-(α-1)} was nearly equal to 1/a at a low strain, so that the equation (2) can be represented as equation (4).<br>f=ν1RT(α-1/α2)+N0RT(1-1/α2) exp (E/RT) (4)<br>The number of effective chains obtained by the swelling method has been found to be equal to ν1 calculated from equation (4), and ν1RT (α-1/α2) increased with the temperature. Cohesion energies E of natural and synthetic rubbers derived from equation (4) varied from 1600cal/mol for natural rubber to 3500 cal/mol for SBR containing 40% bound styrene.<br>J. Furukawa, T. Kotani, S. Yamashita, T. Miyahra: J. Soci. Robb. Ind., Japan 34 162 (1961)

Journal

  • NIPPON GOMU KYOKAISHI

    NIPPON GOMU KYOKAISHI 37 (5), 341-347, 1964

    THE SOCIRETY OF RUBBER SCIENCE AND TECHNOLOGYY, JAPAN

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