Pressure dependence of the glass transition and related properties of Solithane 113 elastomer

Abstract

Several studies have been carried out on a polyurethane elastomer (Solithane 113). At atmospheric pressure, dielectric methods were used to study ε^″ over the temperature range from −180 to +20 °C. Three peaks in ε^″ were observed: an α peak associated with the glass transition and two low temperatures peaks ( β and γ). Mechanical tests were peformed to osberve the effect of the pressure‐induced glass transition P_g on the Young’s modulus. The glass transition was studied of pressure from 1 bar to 6.5 k bar by observing the shift as a function of the dielectric α peak with pressure and also by volumetric methods. A densification of the glass and a resultant shift in the glass‐transition temperature could be achieved by forming the glass at high pressures (T_g) as opposed to pressuring the glass formed at 1 bar (T^*_g). It was found that Δβ/Δα≳dT_g /dP, but Δβ/Δα?dT^*_g /dP. At high pressures, dT_g /dP reached a limiting value of 10.4 °C/kbar.