Investigation on the Thermo-Oxidative Degradation of Polyethylene, Poly(vinyl chloride), and Polystyrene Using NiPIm(1.5) and NiPIm(2) Nanocomposites

[Image: see text] In this work, we report the synthesis of two nanoscale composites of nickel, NiPIm(1.5) and NiPIm(2) (NiPIm(1.5) = [Ni(C(3)H(4)N(2))(H(2)O)(5)](HPO(4))(H(2)O)·0.3(C(3)H(4)N(2)) and NiPIm(2) = [Ni(C(3)H(4)N(2))(H(2)O)(5)](HPO(4))(H(2)O)·0.4(C(3)H(4)N(2))·H(2)O), characterization by various instrumental methods and the investigation of the thermo-oxidative degradation of polyethylene (PE), poly(vinyl chloride) (PVC), and polystyrene (PS) in the presence of both nanocomposites. All of these polymers are subjected to thermal treatment with and without composites at 353 K for 120 min. The rate of degradation is maximum with NiPIm(2) for all three polymers, PE—13.1522%, PS—13.6152%, and PVC—8.04%, whereas with NiPIm(1.5), PE—7.3128%, PS—11.9837%, and PVC—4.9106%. The percentage of degradation in the presence of composites is much greater than the percentage of degradation without composites. The specific heat capacities of NiPIm(1.5) and NiPIm(2) are −148.42 and −348.64 J kg(–1) K(–1), respectively. The degradation process takes place by free radical mechanism. Thermogravimetric and differential thermal analyses revealed that the temperatures corresponding to the formation of composite materials with NiPIm(2) are 338.76, 331.78, and 354.30 K for PE, PVC, and PS, respectively. The temperatures of formation of the above composites are found to be less than that of NiPIm(1.5). The degraded residues of polymers indicate that ester is formed in each case along with other byproducts containing imidazole. Infrared studies revealed the thermal oxidation of hydroperoxides and the formation of ketone.