DYNAMICS AND MORPHOLOGY OF POLYOLEFINIC ELASTOMERS BY MEANS OF C-13 AND H-1 SOLID-STATE NMR

An extensive study of both H-1 and C-13 T-1 (spin-lattice) and T-1 rho (spin-lattice in the rotating frame) relaxation times as well as T-CH (proton-carbon cross-polarisation times) was undertaken in order to i nvestigate the morphology and dynamics of an ethylene/propylene/ethyli dene-norbornene terpolymer and two ethylene/propylene random copolymer s obtained using different catalytic systems. Several selective n.m.r. techniques were first used in order to obtain information on the stru cture and phase composition of the three copolymers. Two of the sample s were found to consist of a single phase, whereas the copolymer obtai ned with a Ti-based catalyst clearly showed three phases: rubbery ethy lene/propylene random copolymer, crystalline polyethylene, and isotact ic crystalline polypropylene. Moreover, a fourth phase, made of 'rigid ' amorphous polyethylene, bordering the crystalline polyethylenic regi ons, was singled out by means of H-1 T-1, C-13 T-1 rho and T-CH measur ements. In the same sample the dimensions of the crystalline domains d ispersed in the rubber matrix were roughly estimated on the basis of t he proton relaxation times. Qualitative and semi-quantitative informat ion on motions in the kHz and MHz ranges was derived from carbon relax ation times. (C) 1997 Elsevier Science Ltd.