Structure-property behavior of polyethylene exposed to different types of radiation

Abstract

A detailed study was performed on unirradiated low-and high-density polyethylene (LDPE and HDPE) films as well as irradiated films with different types of radiation such as 60 Co ␥ rays, thermal and fast neutrons, and electron beam irradiation. The structural changes of PE films were characterized by Fourier transform infrared (FTIR), Fourier transform Raman (FT-Raman), and ultraviolet (UV) spectrometric techniques. The results showed significant radiation degradation, crosslinking, and changes in the crystalline and amorphous regions. The influence of ␥-radiation on the structure of PE was found to be more prominent compared to that of thermal neutrons and electron beam irradiation. However, LDPE film was found to be more sensitive to these types of radiation in accordance with HDPE because of its lesser degree of crystallinity.

Characterization of gamma irradiated polyethylene films by DSC and X-ray diffraction techniques

“…The effects of gamma, electron beam, and fast neutron irradiation on LDPE and HDPE films were investigated, showing remarkable changes in the physical and chemical properties of these polymers 10. 11 In these studies, ultraviolet (UV), Fourier transform infrared (FTIR), and Raman spectroscopy were used to monitor the physical and chemical changes, such as structural changes, rearrangement, bond scission and formation, crosslinking, degradation, oxidation, order–disorder change and phase transition.…”

“…Because irradiation causes important modifications in the structure of the PE molecule, such as branching and unsaturation, the geometry of the molecule is altered, preventing to some extent the orientation of the chains to form regular molecular arrangements 11. It follows that the crystalline regions in the polymer should be affected by irradiation and one can expect a gradual decrease in the degree of crystallinity with an increase of irradiation dose 16.…”

“…Such an effect (crystallinity change) can be observed and demonstrated using the following techniques: Infrared absorption from a group that is specific either to the crystal phase or the amorphous phase 17. For example, the change in the proportion of amorphous and crystalline regions was determined from the change in intensities of the absorption bands at 1299 and 1887 cm −1 or 451, 465 and 1018 cm −1 11. 18–20 X‐ray diffraction, by comparing integrated intensities in the crystal peaks with the integrated intensity from the non‐crystalline regions.…”

“…Infrared absorption from a group that is specific either to the crystal phase or the amorphous phase 17. For example, the change in the proportion of amorphous and crystalline regions was determined from the change in intensities of the absorption bands at 1299 and 1887 cm −1 or 451, 465 and 1018 cm −1 11. 18–20…”

Effect of UV absorbers and hindered amine light stabilizers on the photodegradation of ethylene–octene copolymer

“…26 As observed in the FTIR spectra of sample EOC irradiated for various hours, new characteristic absorption peaks were emerged with increasing the irradiation time, whose intensity was also increased with the increase in the irradiation time. 57 The chain-end unsaturation carbon-carbon double bond, attributed to the vinyl group, was detected by a peak at 908 cm À1 . In the carbonyl region, the absorbance at 1778 cm À1 was due to the C¼ ¼O stretching of lactone.…”