Mass Spectrometric Study on the Evaporation of Volatile Components in Polyethylene

Abstract

Many ions were observed in the spectra of polyethylene heated in the ion source of a mass spectrometer for the temperature range of 150–330°C. With elevation of temperature, the rate of ionic yield displayed a stage of slower increase, Process I, followed by a steeper uprise, Process II. For two commercially available polyethylene, Marlex and Hostalen, it was found that the values of activation energy for the latter stage appeared to be 34 kcal/mol for Marlex and 24.7 kacl/mol for Hostalen. On the contrary, the values for Process I were found to be 6.5±1.2 kal/mol for both samples. According to the mass spectra obtained and the values of activation energy, it was concluded that Process II is corresponding to the stage of thermal degradation, while Process I would be explained by the presence of a stage of evaporation of lighter components included originally in polyethylene.