Degradation and Stabilization of Char-Forming Polymers

This work is composed of three parts. Part 1 is about the relationship between the cross-linking, thermal stability and char formation. For a long time people have believed that cross-linking improves the thermal stability of polymers and renders a polymer less burnable than a non-cross-linked polymer. From the study of cross-linked polydienes, it has been shown that the cross-linking regions do have a better thermal stability than non-cross-linking counterparts, but the cross-linking may lower the thermal stability of non-cross-linking regions. Also the cross-linking structures rather than the numbers of cross-linking determine the char formation. Part II studies the thermal degradation of poly(vinyl chloride) in the presence of a second polymer such as polystyrene. The purpose of this work is to elucidate the stabilizing mechanism of polystyrene on the thermal degradation of poly(vinyl chloride). The traditional explanation was through hydrogen that the changes in the physical state and Friedel-Crafts reactions contribute to the stabilizing action of polystyrene. Part III addresses the thermal degradation of poly(sodium 4-styrenesulfonate) by TGA/FTIR, NMR, and other techniques. The goals of this work are to examine the possibility of sodium 4-styrenesulfonate as a char-former and understand its thermal degradation pathway and potential use as a flame retardancy additive in polystyrene. Also the comparison of thermal degradation and thermal oxidative stability of poly(styrene-co-sodium 4-styrenesulfonate) and their simple blends concludes that blends have better thermal oxidative stability because blends can produce graphite-like char while copolymers do not