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Predecessor
Volume 42, Issue 5
Displaying 1-7 of 7 articles from this issue
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Y. Umezawa, N. Sakurai, K. Amada1969 Volume 42 Issue 5 Pages 329-342
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSThough important and urgent, it has not been possible to solve problem of the conditional optimization in the non-linear field, where both the objective and conditional function are non-linear.
The authors worked out a new method of computerizing the conditional optimization. The second-order polynominal function was used as the mathematical model which elucidated the relation between the amount of the ingredients in rubber compound and the physical characteristics in the cured rubber. The unknown coefficients of the polynominal function were estimated by the method of least squares.
The method presented here is helpful for compounders to prepare the rubber compound in complience with the compounder's desire.View full abstractDownload PDF (1047K) -
PART III. THE ULTIMATE TENSILE PROPERTIES OF THE FILLED AND UNFILLED NR VULCANIZATESK. Fujimoto, T. Migita1969 Volume 42 Issue 5 Pages 343-353
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSFor the purpose of making clear the influence of crystallization with elongation on the failue properties of rubber vulcanizates from the viewpoint of molecular structure, we investigated the relation between the ultimate tensile properties and the rubber network structure for NR vulcanizates with and without carbon-black, and the following conclusions were obtained.
1) NR vulcanizates show the maximum ultimate elongation at the temperature TE, which is pretty higher than the glass transition temperature, and the ultimate tensile stress and strain decrease abruptly beyond this temperature TE.
2) The temperature TE, which corresponds to the maximum elongation, is equivalent to the temperature TH, where the crystallization of polymer is interrupted. In case of carbonblack filled rubber vulcanizates, the temperature TS, where the main rupture position changes from filler surface to rubber matrix, coincides with TE. In addition, these temperatures mentioned above are linearly related to the molecular length n•l between crosslinks. Namely,
TH=TH=TS∝n•l
3) In case of pure gum vulcanizates, the following relationship holds approximately between the maximum ultimate elongation ratio αb(TE) and the network density ν, calculated from swelling degree.
αb(TE)∝νS-1/2
This equation is same as the theoretical one which is obtained from the simple assumption of full stretching of Gaussian molecular chain.
4) The ultimate tensile stress σb at one temperature T show the maximum value for the critical value of νS. This temperature T is equivalent to the TH of rubber vulcanizates with the same νS as the critical value mentioned above. This fact means that the maximum ultimate stress is obtained under condition that the molecular chains can be most easily arranged to the elongation direction at that temperature.View full abstractDownload PDF (1009K) -
M. Tsukasa, Y. Miyazaki, Y. Minoura1969 Volume 42 Issue 5 Pages 354-358
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSIt has been found that rubbers are cross-linked by aldehydes; and especially, in case of acidic polymers, that they can be cross-linked sufficiently without catalysts. In this paper, the cross-linking effects of chlorine containing polymers such as polychloroprene, chlorosulfonated polyethyrene and polyvinyl chloride are examined. Adding an active filler, hydrated silica 20 or 40phr of volumes, to Neopren WHV and varying the amount of α-polyoxymethylene 0, 2, 4, 6, 8 or 10phr, the initial cross-linking rate is measured, and then the most rapid of it is compounded about 4phr. The strongest compound is obtained when 2phr of α-polyoxymethylene is compounded and press-heated at either 130 or 150°C. Polyvinyl chloride is not cross-linked by aldehyde because of the excessive de-hydrochlorination under heating. Hypalon is cross-linked sufficiently by using a small amount of acid, and Hycar 1203J is cross-linked without using acid.View full abstractDownload PDF (413K) -
M. Tsukasa, Y. Miyazaki, Y. Minoura1969 Volume 42 Issue 5 Pages 359-364
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSWhen SBR was cross-linked by the system using α-polyoxymethylene, a part of stannous chloride was replaced by xylilmercaptan, phenol, m-xylene or maleic acid. Thereby phenol turned out the most effective co-agent. Subsequently, phenols were added with α-polyoxymethylene in hydrated silica loaded SBR compound, and the reaction was examined in presence of the phenols under heating. An apparent cross-linking occurred when resorcine, phenol, m-, p-cresol and bis-phenol A were added, but the strength of the rubbers was low. The rubbers obtained, however, had high hardness and high modulus, so that the formation of a lower condensation resin was suspected. Varying the molar ratio of phenol and α-polyoxymethylene, the reaction was examined, and the highest strength was obtained at molar ratio 1.5; and increasing the ratio of phenol, the rubber was darkened and a resin-like rubber was obtained. Further, at constant α-polyoxymethylene, the molar ratio of stannous chloride and phenol was varied. As the result, the highest strength was obtained when phenol 3.76 and stannous chloride 3.30phr were used.View full abstractDownload PDF (439K) -
S. Yabuta, Y. Obata, S. Kawabata, H. Kawai1969 Volume 42 Issue 5 Pages 365-369
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSThe mechanical properties of rubber vulcanizates under finite deformation have been investigated both theoretically and experimentally. There remain many unsolved questions in the analysis of the elastic properties of rubber vulcanizates, however. These practical examples can be observed in the Mooney-Rivlin plot which gives nonlinear curves resulteting in difficulties in the analysis.
In general, the tensile properties are revealed only by the simple extension test which does not give information enough to analyze the mechanical behavior. This may be attributed to the fact that the range of elastic deformation is large and the mechanical behavior is nonlinear. These defects may be improved by using biaxial tensile measurement.
In the present paper, the results of biaxial tensile measurement on NR vulcanizate are reported. The energy functions such as ∂W/∂I1 and ∂W/∂I2 also are estimated as a function of invariants of deformation tensor, I1 and I2.View full abstractDownload PDF (413K) -
[in Japanese], [in Japanese]1969 Volume 42 Issue 5 Pages 370-377
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESSDownload PDF (576K) -
[in Japanese]1969 Volume 42 Issue 5 Pages 378-390
Published: 1969
Released on J-STAGE: April 16, 2008
JOURNAL FREE ACCESS
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