Abstract
Polyurethane-elastomer material was synthesized with an aim to determine the influence of the polyurethane chemical structure as well as of the length of the linear chains between cross-linking points on properties in such systems. Polyurethane elastomers were obtained from polyurethane prepolymers with a mixture of the diol or/and glycerin. The polyurethane prepolymers were synthesized from 4,4’-diphenyl methane diisocyanate and polyesters with molecular weight of about 2000. These polymers had improved properties and have formed flexible films with well stress-strain properties. This effect was explained by the formation of hydrogen bonds between urethane groups, independent of the polyurethane linear chain length, physical networks, which control the molecular mobility. By contrast, the chemical nature of the cross-linker precursors strongly influences the mechanical properties and glass transition. We report the synthesis of the cross-liked polyurethane elastomers and study its properties, the influence of the nature and length of the hydrocarbonate chain of the various micro glycols on the thermal and mechanical characteristics. The chemical cross-linking process decreases the soft segment crystallinity and increases stress properties. Investigation of these properties showed that the elastomers could be tailor made in order to fulfill industrial needs. Keywords: polyurethanes, cross-link, chain extenders, mechanical properties, thermal behavior