Electron beam irradiation studies of polyethylene maleic anhydride on their Chemical and Thermal properties.

Abstract

The electron beam (e-beam) irradiation effects on polyethylene maleic anhydride (MANPE) are investigated by spectroscopic and thermal methods. The MANPE irradiated with electron beam to a radiation dose of 30, 60 and 90 K Gy and the resultant changes in their chemical structure and thermal properties  have been investigated by Electron spin resonance (ESR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods.  The irradiated MANPE has shown complex ESR line shapes under different conditions.  The analysis of ESR spectra suggests the formation of macro-radicals of the type (–CH 2 -ĊH-CH 2 -)(I) and peroxy radicals of the ROO (II). The temperature dependent ESR studies suggest that the free radicals are trapped in the amorphous regions of the polymer. The g- values of free radicals at different temperatures are measured and  reasons for variation in g- values is explained.  Bloch analysis is used to calculate activation energy associated with the decay of free radicals.  The FTIR analysis indicates the shifting of absorption bands and formation of new absorption bands corresponding to unsaturated groups and carbonyl groups centered around 1600 cm and 929 cm -1 . The e-beam irradiation of MANPE caused the decrease of transition temperature and increase of melting enthalpy and degree of crystallinity with increase of radiation dose as per differential scanning calorimeter studies. The results indicate that on irradiation MANPE preferably undergo degradation at low dose of irradiation and preferably undergo crosslinking at high doses.