@article { ISI:000263212700021,
	title = {Effect of gamma-dose rate on crystallinity and morphological changes of gamma-sterilized biomedical polypropylene},
	journal = {Polymer Degradation and Stability},
	volume = {94},
	number = {2},
	year = {2009},
	month = {FEB},
	pages = {272-277},
	publisher = {ELSEVIER SCI LTD},
	address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND},
	abstract = {<p>The present work is aimed to study the changes in crystallinity and morphology of biomedical polyolefins after gamma-sterilization. The isotactic polypropylene (iPP) films were sterilized by gamma-radiation and the changes were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and atomic force microscopy (AFM) techniques. The effect of dose rate on crystallinity changes also was focused. It was found that crystallinity and morphology significantly changed with gamma-irradiation. There was an increase in crystallinity Lip to 10 kGy accompanied with decrease in viscosity and mechanical properties. The changes in crystallinity mainly depend on gamma-irradiation dose and dose rate. The rise in crystallinity was attributed to chain scission and forming new perfect lamellae. However, the reduction was accompanied by occurrence of gamma- and beta-phases and crosslinking. Possible explanations for transitions in phases are also discussed based on our results. (C) 2008 Elsevier Ltd. All rights reserved.</p>},
	keywords = {Crystallinity, Dose rate, Gamma radiation, mechanical properties, Morphology, polypropylene},
	issn = {0141-3910},
	doi = {10.1016/j.polymdegradstab.2008.10.027},
	author = {Alariqi, Sameh A. S. and Kumar, A. Pratheep and Rao, B. S. M. and Singh, R. P.}
}
@article { ISI:000286469900005,
	title = {Gamma-initiated oxidation of isotactic polypropylene: effect of gamma-dose rate on durability},
	journal = {Arabian Journal for Science and Engineering},
	volume = {36},
	number = {1},
	year = {2011},
	month = {JAN},
	pages = {29-38},
	publisher = {SPRINGER HEIDELBERG},
	address = {TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY},
	abstract = {<p>The effect of gamma-irradiation dose rate on the chemical, molecular, and mechanical properties of isotactic polypropylene (iPP) films was investigated using three different Co-60 sources with dose rates of 600, 660, and 780 Gy h(-1). Fourier transform infrared spectroscopy coupled with chemical derivatization with NO and SF4, and measurements of the elongation at break, toughness, and molecular weight were used to describe the effects of gamma-dose rate on iPP. It was found that the formation of oxidation products depended significantly on the dose rate. However, the kinetic accumulation of ketones were more sensitive to the dose rate of gamma source. Degradation induced by gamma-radiation depends on the dose rate-the degradation of mechanical properties was more significant at a low dose rate than at a high dose rate. It was found that the lower the dose rate, the higher the degree of oxidation in terms of the formation of gamma-products. The mechanism of gamma-degradation is discussed based on the correlation between the changes in chemical and physical properties upon exposure to gamma-radiation.</p>},
	keywords = {Chemical and physical properties, Dose rate, gamma-irradiation, polypropylene},
	issn = {1319-8025},
	doi = {10.1007/s13369-010-0006-8},
	author = {Alariqi, Sameh A. S. and Singh, R. P. and Rao, B. S. M.}
}
