Time derivative of DSC and dielectric analysis of elastomeric poly(thiourethane-urethane)/Cloisite 30B clay nanocomposites

Poly(thiourethane-urethane) (IPUPS) was prepared by a two-step polyaddition reaction between the isocyanate group of a polyurethane prepolymer and the thiol group of a polysulfide, along with subsequent addition of a mixed polyol (i.e., glycerol + trimethylolpropane) as chain-extender. Formation of thiourethane bond in synthesized IPUPS was confirmed from FTIR spectrum. The nanocomposites were prepared by ultrasonication-assisted dispersion of Cloisite 30B nanoclay in the as-prepared IPUPS matrix with varying filler loading at 2, 4, 8 and 16% (w/w). Dispersion of nanofiller was analyzed by XRD and TEM. The thermomechanical properties of the hybrid elastomeric nanocomposites were analyzed by DMA. Interaction between nanofiller and the elastomeric matrix was confirmed from the red shift of -OH peak in FTIR spectrum. Interfacial interactions between the nanofiller and poly(thiourethane-urethane) matrix in the nanocomposites have been investigated by analyzing the time derivative of the heat flow, measured by differential scanning calorimetry, i.e., d(DSC), as well as with the frequency and temperature dependence of dielectric constant. The d(DSC) study revealed how the soft segment influences the elastic nature of elastomer through the polymer/nanoclay interphase. A 2% loaded nanocomposite exhibited the highest elongation-at-break and 16% loaded nanocomposite exhibited the highest tensile strength, whereas, the critical concentration of nanofiller was found as 4% to achieve effective polymer-filler interaction and the highest dielectric constant. [GRAPHICS] .