6533b839fe1ef96bd12a58a7

RESEARCH PRODUCT

Pseudo-solid echoes of proton and deuteron NMR in polyethvlene melts

subject

description

The solid echo technique is applied to determining residual dipolar and quadrupolar couplings in molten polyethylene (PE) and deuterated PE, respectively. The residual coupling defined by the square root of the second moment is about 1% of the corresponding quantity in the solid. It increases with molecular weight, and decreases with rising temperature. A theoretical treatment of time dependent residual couplings yields a decay time that is found experimentally to be about 0.1 ms in molten PE, and independent of molecular weight and temperature within our limits of accuracy. The residual coupling is discussed in relation with chain entanglement in PE. Measurements of the spin-lattice and spin-spin relaxation time are related with the more rapid segmental motion of PE chains.