Change of properties of a densely crosslinked polymer induced by solid-phase deformation and annealing

Promising aspects of the structural modification of polymers and polymer composites with the aid of high pressures

“…14 increase in e, the modulus of elasticity of the highcrosslinked network EP-7 (n = 9610 20 cm 73 ) increases strongly in tensile tests and diminishes in compressive tests. 178 For individual specimens, deformed to the extent of 45%, the values of E obtained in extension exceed those for the control specimens by a factor greater than 2. The density varies nonmonotonically, reaching a maximum at e & 25%.…”

“…The study of the relaxation properties of the high-crosslinked network EP carried out on the original specimens and the extrudates has shown that, for e = 35% and 45%, there is a sharp increase in molecular mobility induced by the loosening of the material and the partial mechanodegradation of the network. 178 The relaxation of the stress in the deformed polymer proceeds more vigorously than in the control specimen with increase in e, the stress required for the maintenance of the specified deformation diminishes, the rate of relaxation increases, and the relaxation continues until the attainment of lower stresses. The fitting of the experimental relations with the aid of new relaxation memory functions 177 made it possible to establish that the stress relaxation process in the extruded high-crosslinked network EP is determined with equal probability by the kinetics of the interaction of the relaxators (microheterogeneities) and the kinetics of the diffusion of the nonrelaxators.…”

“…The results of thermomechanical studies agree well with NMR data. 178 The microstructure of the undeformed high-crosslinked network EP consists of globule-like formations made up of smaller elements. Hydroextrusion leads to characteristic changes in the morphology of the polymer.…”

“…The fitting of the experimental relations with the aid of new relaxation memory functions 177 made it possible to establish that the stress relaxation process in the extruded high-crosslinked network EP is determined with equal probability by the kinetics of the interaction of the relaxators (microheterogeneities) and the kinetics of the diffusion of the nonrelaxators. 178 Compared with the original material, the number of microheterogeneities in the extrudates diminishes.…”