Gamma射线消毒环氧乙烷消毒前后的PS的性能.pdfVIP

Technical Bulletin NOVA Chemicals Effects of Gamma Irradiation and Ethylene Oxide Sterilization on the Appearance and Physical Properties Of Crystal and Impact Polystyrene TECHNICAL DATA The sterilization of plastics has become increasingly important as the use of plastics in medical applications and aseptic packaging has become more frequent. Sterilization by high-energy radiation, such as gamma or electron beam irradiation, is popular, since it avoids the use of chemicals that may leave residues in the plastics. Alternatively, a simpler process involves exposure of the specimens to ethylene oxide gas for a pre-determined length of time. The effects of both methods were evaluated in this long-term study, and dosage levels were equivalent to and/or exceeded the normally required amounts. Molded 1/8 tensile bars, Izod bars, and 2.5” diameter disks of these two materials were exposed to both methods of sterilization to evaluate the effect on physical properties. Properties were tested before and after exposure to measure the initial effects, and then samples were retained and tested over time to evaluate long-term effects. The complete results of the evaluations of the exposed materials are presented in Tables 3 and 4. The following conclusions can be made based on these results and tables of percent retained properties after 2 years are also included. 1. Physical Properties and Yellowness Indices of High Heat Crystal Polystyrene The melt flow indices of the High Heat Crystal Polystyrene samples were slightly affected by exposure to both types of sterilization methods. The tensile strength and % tensile elongation properties were relatively unaffected by exposure to 25 kGray (2.5 Megarads, single dose) and 50 kGray (5.0 Megarads, double dose) of gamma irradiation. Ethylene oxide sterilization (single dose) had a more noticeable effect on tensile strength and elongation. The yellown