BROAD-LINE NMR-STUDY OF MOLECULAR-MOTION IN UNIAXIALLY STRETCHED POLYMERS

Capability of NMR technique to study fracture and elementary destructi on acts in polymers is discussed. Tensile stress influences macromolec ular mobility As a rule mobility of macromolecules decreases under def ormation. So far deformation remains reversible,this effect is reversi ble, too. As a result of chain micro-Brownian motion hindering under s tress the amorphous layers can pass from high-elastic to solid state e ven at temperatures rather higher than T(g) measured under initial con ditions.It is mechanical vitrification (not structure changes) that is regarded as the general causes of draw process interruption (destruct ion of polymer). Deformation-induced electron emission was detected. I t is caused by ionization of stressed chains and tunnel transitions of electrons into deep traps. Influence of molecular mobility on the tra ps and their destroying under stress are considered.