Electron induced modifications in the optical properties of polypropylene

Abstract

In this work, the effect of electron beam (EB) irradiation on polypropylene (PP) films has been studied via different techniques, namely: x-ray diffraction and UV–Vis absorption spectroscopy. The PP films were irradiated with a 1.5 MeV electron beam at doses of 5, 10, 20, 50, 70, 100 and 120 kGy. The crystallinity of the PP films was found to increase, slightly, by EB irradiation. The changes in the dipole strength, transition dipole moment, oscillator strength, optical band energy gap and activation energy have been investigated as a function of the irradiation dose. The results exhibited an increase in both the dipole moment and the oscillator strength; meanwhile, a decrease was found in both the energy gap and the activation energy with increasing dose. The obtained results explored a linear relation plotted between each of the dipole moment, the oscillator strength and the activation energy and the irradiation dose that showed good correlation coefficients. The results suggest the possible use of this polymer as a dosimeter for electron beams in the dose range of interest (0–120 kGy) by means of UV–Vis spectrophotometry.

Photoluminescence and optical properties of He ion bombarded ultra-high molecular weight polyethylene

“…1). These defects give localized states in the forbidden gap resulting in the increase in the number of charge carries in the conduction band due to formation of lower energy states [31]. The gradually decrease in the values of the activation energy with increase ion fluencies confirms the previously obtained decrease in the optical energy gap values.…”

“…It was found that E a is inversely proportional to the He ion fluence. This gradually decrease in the values of activation energy might be attributed to the formation of clusters group [31] and/or increase in the defects (cf. Fig.…”

MeV energy electron beam induced damage in isotactic polypropylene

“…The residual carbon left in polypropylene acquires graphite like form. Therefore, conjugation and carbonization seem to be main process responsible for decrease in the band gap of polypropylene [9,16].…”

“…This is used in many applications such as radiation-sterilized medical and pharmaceutical components, food packaging materials and cosmetics [5]. A literature survey [6][7][8][9][10][11] indicates that effects of 14.89 MeV electron irradiation on polyethylene and polystyrene in the dose range of 57.6-576 KGy showed a greater red shift in absorption edge of polyethylene as compared to polystyrene [6]. Whereas, the enhancement in the thermal properties, dielectric constant, dielectric loss and crystallinity of 2 MeV and 1.5 MeV electron irradiated polypropylene has also shown considerable modifications [7,8].…”

Measurement of integrated absorption cross-section, oscillator strength and number density of caffeine in coffee beans by integrated absorption coefficient technique

“…In this research, the oscillator strength of caffeine in distilled water and dichloromethane was calculated by absorption measurements. Oscillator strength was related to the molar decadic absorption coefficient by the following equation (Forsman & Clark, 1973;Georgakopoulous, Grondelle, & Zwan, 2004;Radwan, 2007):…”