Nonisothermal Kinetic Analysis and AC Conductivity for Polyvinyl Chloride (PVC)/Zinc Oxide (ZnO) Nanocomposite

The behavior of polyvinyl chlorine (PVC)/zinc oxide (ZnO) nanoparticles was investigated. To improve the dispersion and distribution of zinc nanoparticles within the host polymer (PVC), they were treated with water before being added to the polymer. The nanocomposite samples were prepared by casting method using different weight ratios of ZnO nanoparticles. The prepared nanocomposite samples were characterized by thermogravimetric analysis (TGA). Both thermal stability and kinetic analysis of the prepared samples were investigated. The ZnO nanoparticles lower the activation energy and decrease the thermal stability of PVC. Kissinger, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose models were used in the nonisothermal kinetic analysis of PVC/ZnO nanocomposite samples. The thermal stability behavior due to the addition of zinc oxide nanoparticles was explained and correlated with the behavior of the kinetic parameters of the samples. The AC conductivity as function of frequency and temperature was also investigated. The addition of ZnO nanoparticle increases the AC conductivity, and the temperature-independent region decreased by increasing temperature. Both S and A coefficients were predicted using the Jonscher power law and OriginLab software. The trends of S and A coefficients were discussed based on the glass transition of the host polymer.

New fire-resistant epoxy thermosets: nonisothermal kinetic study and flammability behavior

New fire-resistant thermosets are prepared based on a bisphenol A-epoxy resin which is thermally crosslinked in the presence of dicyandiamide and two phenols containing phosphorus atoms. The thermosets are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis (TGA), and microscale combustion calorimetry (MCC) tests. A nonisothermal kinetic study is performed based on processing of TGA data applying the method proposed by Vyazovkin. The lifetime prediction analyses establish that the phosphorus-containing polymers could be used at a constant temperature of 200°C up to 200–780 min. The MCC tests reveal an improvement of the flammability behavior, as well as a significant heat release capacity reduction for phosphorus-containing samples compared to the sample which has no phosphorus component.