The influnce of network imperfections on the mechanical properties of elastomers with isocyanurate rings
Polyurethanes generally have low thermal stability and thermal degradation can occur during exploitation above 180 °C. It is assessed that the modification of the polyurethane chains via forming thermally stable permanent heterocyclic structures can improve the thermal stability. Polyurethane foams based on networks with isocyanurate rings are generally insulation-grade and have excellent thermal stability. In order to assess a quantitative contribution of pendant chains, polyurethane soft elastomers based with a controlled architecture were synthesized by prepolymer procedure. A simple strategy was developed to prepare networks based on poly(oxypropylene)diol and 2,4-TDI by adding the monofunctional component for prepolymer synthesis. Network formation was described using the cascade theory. Mechanical properties were determined from stress-strain experiments. It was estimated that the increase of the monool in the precursor formulation influenced the increase of energy at break and the elongation but affected to decrease of Young modulus.