000			01344nam a2200145Ia 4500
008			220216s9999 xx 000 0 und d
100			_aAllen Geoffrey
245		0	_aMolecular mobility in rubbers
260			_bJournal of Natural Rubber Research _c1986
300			_a51-57
520			_aNeutron beams be obtained in pulsed beams of virtually monchromatic character at wavelengths of about 5 A. The momentum associated with the beam is high and the energy low. Thus neutrons are ideal for studying the diffulsional motions of liquids in scattering experiments. In the past ten years, neutron scattering has been used to determine the average dimensions of individual chains in bulk rubbers and plastics, to study the dynamics of polymer chains in raw rubbers and melts and cross-linked networks and to measure the rotation of side groups. Results show that the Rouse model of molecular chain dynamics is more appropriate than the Zimm model for rubber. In networks, the sections of chain between cross-links from essentially the same chain motion as in the raw rubber, but the junction joints move more slowly. The energy barrier to internal rotation of the methyl side groups in polypropylene oxide is found to be approximately 15 kJ mol-1 in line with the expected value.
650			_aMolecular mobility
650			_aRubber
942			_cJS
999			_c63208 _d63208