Effect of Cross-Linking Density on Dynamic Mechanical Properties of Polynorbornen Compounds

The effect of cross-linking density on dynamic mechanical properties of polynorbornen (PNR) sheets containing an aromatic process oil was investigated. The mechanical loss tangent (tan δ) and loss modulus (E″), measured as a function of temperature, had a single peak corresponding to α dispersion. The increase in the cross-linking density remarkably shifted the tan δ and E″ peaks to the higher temperature side, while the peaks became broader and the peak value of tan δ notably decreased. The temperature of tan δ peak had an Arrhenius type frequency dependency, and the activation energy increased with increasing density of cross-linking. The equation of Sichina well predicted the peak temperature of tan δ, using Tg from DSC and the activation energy. The tensile strength increased linearly with increasing cross-linking density.