Thermal decomposition of amide and imide derivatives of maleated polyethylene

Abstract

The thermal decomposition behavior of six derivatives of maleated polyethylene was investigated by high-resolution pyrolysis gas chromatography-mass spectrometry. The results revealed that substituents attached to maleated polyethylene as amides formed from secondary amines were significantly less stable than imides formed from primary amines. Morpholine amide and N-methylaniline amide derivatives of maleated polyethylene underwent significant decomposition at 160°C and substantial decomposition at 200°C. In contrast, the imide derivatives of maleated polyethylene were stable for long periods of time at elevated temperatures. Following 2 min of heating, the first traces of decomposition were detected at 200°C for the 2-aminoanthrancene imide derivative, at 255°C for the 2-phenethylamine imide, and at 280°C for the 9-aminomethylphenanthrene imide. With the exception of the 9-aminomethylphenanthrene imide, all other derivatives decomposed to form the corresponding amine as the single most significant volatile product. The most likely explanation for this result is that the polymer contained small amounts of succinamic acid that did not close to form the imide. We concluded that the imide was stable even to 315°C and that the amine was lost from β-carboxyamide groups present in the sample. In the 9-aminomethylphenanthrene imide derivative, we observed no loss of amine. Instead, we observed an alternative fragmentation process yielding 9-methyl phenanthrene. The dependence of the thermal stability of these various derivatives of maleated polyethylene has important implications for the design of reactive-blending strategies for polyolefins with other functional polymers.