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Thermal Stability and Combustion Behaviors of Poly(oxybutylene)amides

Polymerization of 1,2-epoxybutane (BO) with various amides led to a family of gasoline detergents useful for preventing automobile engine valve deposits. Effective compounds are amphiphilic copolymers consisting of a hydrophobic polyoxybutylene backbone and hydrophilic amide functionalities. The engine performances of these polymer additives were correlated with their thermal stability and the combustion behaviors at high temperature. Investigated by using a thermal gravimetric analysis (TGA), we found the thermal stability to have the following trend according to the backbone structures of oxyethylene > oxybutylene > oxypropylene. Furthermore, the presence of amide or multiple amide functionalities in the structures greatly enhanced the backbone stability up to 100°C in air and 36°C in nitrogen by comparing 50 wt% decomposition temperatures of the TGA data. The amides are considered as built-in antioxidants for free-radical scavenging and backbone stabilizers.