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

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