Abstract
Rubbery network polymers can be realized where network polymers have low crosslink density and degree of molecular motion of polymer chains between crosslinks are very high. Typical physical properties of them are reversible very large deformation and very low modulus. They are based on entropy elasticity. In this short review, pulsed NMR studies of these materials focused on the degree of molecular motion will be introduced with several examples. They are characteristics of rubber elasticity from the view point of physics, change of molecular motion of rubber chains and crystallization under elongation, molecular motion of rubber chains in filler reinforced composites, molecular motion and phase transition of gels, physical properties of thermoplastic elastomers and molecular motion, and so on. In the last, physical properties of rubber bearings for seismic isolation will be mentioned as an interesting example of the extension of this kind of studies.
