Four typical polymer glycols were used as glycol component for preparation of polyurethane elastomers.
Among them, polyester-glycols are polybutylene adipate and poly-(ε-caprolacton). Polyether-glycols are polyoxyethylene and polyoxypropylene glycol. The syntheses of polyurethane elastomers were carried out by the method of one-shot process in DMF solution. The molecular weight of the polymers obtained were almost the same in the range of about 940 to 1090.
As a result of the measurement of temperature dispersion, the only dispersion of dynamic loss of each polymers were observed in the range of -90°C to 120°C. Similarly, these polymers have dielectric dispersion. The temperature position did not exactly correspond each other but the order of these dispersion was in good agreement with the both experimental values.
It should be noted that both relaxation phenomena are based on the same of molecular motion, because the apparent activation energys of both relaxation were in fair agreement.
For the values of the activation energy, it can be assumed that the dispersion is on the basis of main dispersion.
More over, the polyurethane prepared from polyester-glycol has good electric conductivity compared with the one prepared from polyester-glycol.

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Vulcanized natural rubber samples with TT and DPG plus S as a vulcanizing agent have been prepared with the same crosslink density calculated from the swelling method assuming the homogeneous crosslinking throughout the sample. Heterogeneity in crossling density of the samples has been analysed by the use of X-ray small angle scattering, freezing point depression and pulsed NMR from the morphological and molecular motional point of view.
It is concluded that there are collectively crosslinked rubber phases and there is a broad distribution in the radii of them and the distance between them. Vulcanizates with TT as a vulcanizing agent have greater heterogeneity in crosslinb density from the above point of view.
In the transition region, short and long molecular correlation time is observed and the sample can be regarded as a heterogeneous system with broad distribution in its molecelar motion. In the glassy and rubbery region, the results can be described with single correlation time except that in the rubbery region the NMR absorption line given by the Fourier transform of the free induction decay can be observed intermediate between Gaussian and Lorentzian shape on account of chemical shifts of the various radicals in the rubber molecule.

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To decide on the mechanism of the vulcanization of the natural rubber, the reaction of 1-methylcyclohexene, as a low molecular weight model compound for rubber, with sulfur and benzylmercaptane were studied.
The mole ratios of 1-methylcyclohexene to sulfur were 100/1.4 and 100/12.5, and in the reaction of 1-methylcyclohexene with mercaptane, equivalent mixture of the reactants in the mole ratio was used. The reactions were carried out at 140°C. in a sealed tube for 24hr. in the dark. The products were isolated by column chromatography on silica gel.
From the results of the elemental analpsis and infrared spectra of the isolated products, it was confirmed that hydrogen sulfide, 3-methylcyclohexene and different sulfides shown below, were formed in the reactions.
From these results, it was found that in the initial stage, addition of sulfur to olefin went by free radical mechanism, and as mercaptan, formed in subsequent reaction step, coexist with sulfur, ionic addition reaction of mercaptane to double bond in the olefin occured competitively with free radical reaction._??_

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