Changes in physicochemical and mechanical properties of gamma-irradiated polypropylene syringes as a function of irradiation dose

The effect of gamma-irradiation on mechanical, thermal, physicochemical and structural properties of polypropylene (PP) syringes was studied. Irradiation doses of 30, 60 and 120 kGy were used with non-irradiated PP syringes serving as control samples. Irradiation caused a significant deterioration in mechanical properties of samples. The compression strength of whole syringe body decreased with increasing irradiation dose. Similarly % extension at break decreased with increasing irradiation dose. Of the physicochemical properties tested, both degree of yellowness and extractable radiolysis products increased with increasing irradiation dose. Melting temperature as well as specific melting enthalpy decreased with increasing irradiation dose. Minor differences in FTIR spectra were observed, mainly in the region of 1720 cm(-1), corresponding to the absorption of carbonyl compounds indicating the formation of increased amounts of oxidation products at high irradiation doses. Gas chromatography-mass spectroscopy analysis indicated the formation of a number of radiolysis compounds as a result of irradiation. The number and concentration of these compounds increase progressively with increasing dose until 60 kGy. At the same time a number of compounds initially present in non-irradiated syringes were destroyed by irradiation. (C) 2005 Elsevier Ltd. All rights reserved.