Modeling of the Structure and Properties of Poly(Urethane-Isocyanurate) Elastomeric Materials

Abstract

It is reviewed how the rubber elasticity and network formation theories can be utilized for the engineering of elastomers. It is demonstrated by the model networks with a isocyanurate(hexahidro-1,3,5-triazin-2,4,6-trion rings as a junction points how the structure and behaviour of networks can be predicted by joining the theoretical approach and experimental data. The properties of networks were determined by swelling, extraction, differential scanning calorimetry, dynamic-mechanical spectroscopy, photoelastical and stress-strain measurements. Network densities from 0.1×10 -4 mol/cm 3 to 10×10 -4 mol/cm 3 were achieved by variation of the molecular weight of diols. For the network structure estimation the theory of branching processes with cascade substitution was used. Weight fraction, concentration, Mn and Mw for the sol and elastically active, backbone and dangling chains were calculated on the basis of NCO groups conversion or gel content. The existence of trapped entanglements considered in the theory of permanent interchain interactions of the Langley type was analyzed, too. The modulus was calculated by the rubber elasticity theory and compared to the values obtained by photoelastical measurements.