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Rubber elasticity demonstration experiments

Plots of cr/(a- 1/a ) versus Ha are found to be linear, especially at low elongation (see Figure 9.15) (57). The intercept on the a = 0 axis yields 2Ci, and the slope yields 2C2. The value of 2Q varies from 2 to 6 kg/cm but the value of 2C2, interestingly, remains constant near 2 kg/cml Appendix 9.2 describes a demonstration experiment that illustrates both rubber elasticity [see equation (9.34)] and the nonideality expressed by equation (9.50). [Pg.454]

Using gelatin as a model cross-linked elastomer, its rubber elasticity can also be demonstrated by a simple stretching experiment. Thin slices of the... [Pg.499]

From the viewpoint of the mechanics of continua, the stress-strain relationship of a perfectly elastic material is fully described in terms of the strain energy density function W. In fact, this relationship is expressed as a linear combination erf the partial derivatives of W with respect to the three invariants of deformation tensor, /j, /2, and /3. It is the fundamental task for a phenomenologic study of elastic material to determine W as a function of these three independent variables either from molecular theory or by experiment. The present paper has reviewed approaches to this task from biaxial extension experiment and the related data. The results obtained so far demonstrate that the kinetic theory of polymer network does not describe actual behavior of rubber vulcanizates. In particular, contrary to the kinetic theory, the observed derivative bW/bI2 does not vanish. [Pg.122]

Figure 5 demonstrates the different behaviour resulting from Eqs. (49) and (54) in the case of uniaxial compression. We also tested the elastic potential (Eq. (44)) in the two cases v = 1/2 and v = —1/4 by comparing the corresponding stress-strain relations with biaxial extension experiments which cover relatively small as well as large deformation regions for an isoprene rubber vulcanizate. In the rectan-... [Pg.64]

Fig. 3.5 Illustration of the experiment demonstrating the Gough-Joule effects. The light will heat the rubber strip, increases the latter s elastic modulus and then decreases the displayed weight in the electronic balance. Switched-off the light, the displayed weight will be gradually recovered... Fig. 3.5 Illustration of the experiment demonstrating the Gough-Joule effects. The light will heat the rubber strip, increases the latter s elastic modulus and then decreases the displayed weight in the electronic balance. Switched-off the light, the displayed weight will be gradually recovered...
Figure 5. Summarized data for depth variation of elastic modulus for rubber, two different PUs, PVC, and PS. Bars demonstrate values of elastic bulk modulus measured from tensile experiments. Figure 5. Summarized data for depth variation of elastic modulus for rubber, two different PUs, PVC, and PS. Bars demonstrate values of elastic bulk modulus measured from tensile experiments.
Recent experimental advances reinforce the idea that the microscopic motions and the elastic properties can be usefully interrelated. For example, quasielastic neutron scattering measurements probe the motions of the network junctions [53,54]. Molecular dynamics simulations have also added new insight, for example, by demonstrating the existence of local constraints on the network chains at strand lengths less than the molecular weight necessary for chain entanglements [55]. Recently P NMR spin-lattice relaxation experiments on crosslinked rubber have been used to monitor specifically the dynamics of the network junctions [52,56]. [Pg.821]


See other pages where Rubber elasticity demonstration experiments is mentioned: [Pg.101]    [Pg.58]    [Pg.208]    [Pg.208]    [Pg.53]    [Pg.41]    [Pg.269]    [Pg.436]    [Pg.582]    [Pg.10]    [Pg.1237]    [Pg.65]    [Pg.386]    [Pg.182]   
See also in sourсe #XX -- [ Pg.497 , Pg.498 , Pg.499 , Pg.500 , Pg.501 , Pg.502 , Pg.503 , Pg.504 , Pg.505 ]




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