上海科技大学知识管理系统

Background: Cyclic olefin copolymer (COC), synthesized by catalytic copolymerization of ethylene and norbornene, can be applied in medical devices and drug packaging, owing to its many outstanding properties such as good light transmittance, water vapor barrier and biocompatibility. When this type of medical devices or drug package is sterilized by high energy irradiation, COC will inevitably undergo changes such as radiation scission, oxidation, discoloration and so on. It is of great significance to explain the performance change of COC from the free radical reaction initiated by ionization radiation for the radiation sterilization application of COC medical supplies. Purpose: This study aims to investigate radiation effect of COC in the dose range of radiation sterilization. Methods: Effects of γ-rays on chemical structure, free radical, glass transition temperature, thermal stability, molecular weight distribution, surface properties and melt index of the irradiated COC with the sterilization dose were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectroscopy (UV-vas), electron spin resonance spectroscopy (ESRS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), water contact angle (WCA) and melt mass-flow rate measurement. Results: The concentration of free radicals produced by COC irradiation in air increases linearly with the increase of absorbed dose. With the increase of absorbed dose, radiation degradation is dominant, hence the average molecular weight of the radiation oxidation products include carbonyl and hydroxyl compounds decreases, and the surface hydrophilicity is enhanced whilst the melt index is increased. Conclusions: The molecular chain breakage caused by radiation and the reaction between free radicals and oxygen are the main causes of COC degradation. © 2022, Science Press. All right reserved.