The difficulties of wide line NMR or conventional pulsed NMR techniques for the analysis of heterogeneous polymer systems are discussed from the view point of principles of wide-line NMR and system recovery time of pulsed NMR. They are clarified in the case of a simple two-phase model, and the distinguishability of the two phases for both techniques is calculated. In order to overcome these difficulties the applicability of multiple-pulse NMR techniques are studied i.e., the applicability of solid echo for T2 (spin-spin relaxation time) and of solid echo train for Tip (spin-lattice relaxation time in rotating frame). Solid echo and solid echo train techniques are applied to Nylon 6, low-density and high-density polyethylenes. There are obtained T2, Tip and the fraction of the crystalline, intermediate and amorphous phases of Nylon 6, high-density and low-density polyethylenes. In the case of low-density polyethylene, the temperature dependence of T2, Tip and the fraction of the three phases between -120°C to 100°c are obtained.KEY WORDS

It is shown that NMR-linewidth measurements are useful to obtain information about the crosslink density and the average distance between the crosslinks in vulcanized rubber. Inhomogeneous structure of the rubber phase in carbon black-filled rubber is evidence and the thickness of the rubber layer on carbon black is estimated at 50 A˚.

Temperature dependence of dielectric loss, mechancial loss, and dynamic modulus were measured to study polymer blending. Results were as follows: Dielectric loss and dynamic modulus of NR—BR blends showed two peaks corresponding to NR and BR, indicating that the blends were microheterogeneous. A single, broad maximum absorption band observed for SBR—BR blends indicated that the blends were microhomogeneous. Mill mixing and solution mixing of NR and BR made very little difference in blended state and physical properties. Nearly homogeneous SBR—BR blends can be obtained with a few minutes mill mixing. In vulcanization of NR—BR blends, BR was overcured rapidly due to migration of sulfur and accelerators from NR.

Mainly from the temperature dependence of transitions in dynamic modulus, loss tangent, and dielectric loss, associated with microbrownian motions of main chains, it was concluded that blends of NR and BR are microheterogeneous and those of SBR and BR are almost microhomogeneous. Furthermore, even SBR/BR blends tended to be heterogeneous if the styrene content in SBR was increased. On the other hand, unvulcanized SBR/BR blends have been reported to be heterogeneous from observation of phase contrast micrographs. To investigate this vulcanization effect further, measurements of temperature dependence of dynamic modulus and tan δ of unvulcanized blends were compared with those of vulcanized blends.

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