STRUCTURE AND VISCOELASTIC BEHAVIOR OF POLYURETHANE NETWORKS FROM TRIISOCYANATE AND POLYOLS WITH DIFFERENT STRUCTURES

The dynamic mechanical behaviour in the main transition and rubbery re gion was investigated for polyurethane networks produced from triisocy anate and diols based on diethanolamine derivatives and poly(oxyethyle ne). The effects of altering main and side chain length of diols and i nitial molar ratio of hydroxy [OH] to isocyanate [NCO] groups, r(H), o n the shape and temperature position of mechanical functions were dete rmined. While the values of functions in the rubbery region are predom inantly determined by the concentration of the network chains, the sha pe of the functions associated with the main transition region depends also on the topology of the network chains (especially the presence o f dangling chains). The temperature position of the main transition de pends on both submolecular (length of diol backbone and side chain, po larity of diol and concentration of [NCO] groups) and molecular (numbe r and structure of the network chain) parameters.