ISSN:
0449-2978
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Mechanical properties of four kinds of natural rubber vulcanizates differing in vulcanization conditions, and consequently in degree of crosslinking (having values of the Mooney-Rivlin constant C1 ranging from 0.68 to 1.98) were observed under orthogonal biaxial stretching in a range of strain invariants Ii from 3.4 to 9.0 (extension ratios λi from 0.7 to 3.0). The results obtained were analyzed by two methods. One method employed the Valanis-Landel postulate that the strain-energy function W(λ1, λ2, λ3) is a separable symmetric function of the principal extension ratios, i.e., W(λ1,λ2,λ3) = w(λ1) + w(λ2) + w(λ3); the other utilized the contour plots of ∂W(I1, I2)/∂I1 and ∂W(I1, I2)/∂I2 surface within the (I1, I2) domain. The postulate for W was examined in detail with good agreement with experimental results. The dependences of ∂W(I1, I2)/∂I1 and ∂W(I1, I2)/∂I2 surfaces on the degree of crosslinking and temperature were further investigated, with the following conclusions. The surfaces have fairly steep slopes for the region of relatively small deformation (i.e., I1 〈 5) and become flat with increasing Ii for all the test specimens. The slope becomes less steep with decreasing degree of crosslinking. The values of ∂W/∂I1 increase linearly and the ∂W(I1,I2)/∂I2 surface becomes flat, both with increasing temperature: i.e., the temperature dependence of ∂W/∂I1 further depends on Ii. The ∂W(I1,I2)/∂I2 surface has a maximum near 40°C.
Additional Material:
16 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1970.160080607
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