Evaluation of the thermal stabilization effect of polymeric dioctyltin maleate on polyvinyl chloride

Abstract

Polyvinyl chloride (PVC) is a major plastic material with widespread applications. When PVC is heated during the processing period, it presents very low thermal stability and will decomposed to polyene byproducts. To increase the thermal decomposition temperature of PVC and broaden the narrow temperature ranges of related molding products, efficient thermal stabilizers are required to ensure its functionality. Herein, a series of novel polymeric thermal stabilizers, the dioctyltin maleate/styrene/methyl acrylate {P (DOTM/St/ MA)}, dioctyltin maleat/styrene/N-phenylmaleimide {P(DOTM/St/NPMI)}, dioctyltin maleate/styrene/N-pchlorophenyl maleimide {P(DOTM/ St/NClPMI)} and dioctyltin maleate/styrene/N-p-nitrophenyl maleimide {P(DOTM/St/NNOPMI)} copolymers, composing of mature primary heat stabilizing unit dioctyltin maleate, auxiliary heat stabilizing unit N-phenyl maleimide that is able to inhibit the thermal degradation of PVC, as well as methyl acrylate and styrene that have better compatibility with PVC, have been synthesized to improve the thermal stabilization efficiency, taking advantages of their excellent compatibility and dispersibility. The influences of these compounds on the thermal stability of PVC were estimated by Congo red test, pH-meter, and thermal degradation assay in hot oven. The effect of the compatibility on the thermal stability of the PVC stabilizing system was thoroughly explored. It was found that thermal stability was increased with excellent compatibility, demonstrating the effectiveness of these PVC stabilizers. Furthermore, the mechanism of thermal stabilization was discussed through FT-IR and compared with previous studies conducted by other researchers.