Electrical properties and the thermal and photochemical stability of poly(vinyl chloride) films stabilized with some maleyl amide polymers

Abstract

Some maleyl amide polymers were prepared and evaluated as thermal and photochemical stabilizers for rigid poly(vinyl chloride) (PVC). Thermal degradation was determined by measuring the rate of dehydrochlorination potentiometrically. Also, the degree of discoloration was measured for both the thermally degraded and the photochemically degraded PVC. Dibutyltin maleate heat stabilizer was used for comparison in thermal and photodegradation. The applied polymers showed stabilizing efficiency in both thermal and photodegradation by decreasing the rate of degradation, degree of discoloration, and percentage weight loss. The amide polymer of melamine gave better stabilizing efficiency than those of p-phenylenediamine and m-phenylenediamine. A dielectric study was carried out over a frequency range from 100 Hz to 100 kHz at room temperature (∼228C). The results revealed that the stabilizing effect of these maleyl amide polymers depends on the type of stabilizer and its concentration. The dielectric data for the investigated systems were found to be fitted by two absorption regions using the Frö hlich function. These regions are ascribed to the Maxwell-Wagner effect and to intramolecular motion involving the rotation of various segments of the side group as the main chain motion is restricted. The study led to a conclusion that the greater stabilizing efficiency of the melamine amide polymer may be due to the presence of a free amino group (À ÀNH 2 ) that can participate in the stabilization process.

Effect of Natural Rubber/Epoxidized Natural Rubber (90/10) on Dielectric Properties and Crystallization of Metallocene Linear Low Density Polyethylene

“…As shown in Figure 4, the permittivity of all the blends increased slightly as the applied voltage increased from 1 to 5 kV. This result can be explained by the increase in mobility of the polar groups with increase in voltage values, hence increasing the effect of the environment that facilitates the orientation of the mobile groups 20 .…”