Development of methods of forecasting properties of polymer packaging materials which do not cause any changes in medicinal preparations during sterilization

The authors present the results of an investigation of the effect of gamma radiation on the properties of low-molecular moulded polymethyl methacrylates (molecular weight distribution, physico-mechanical properties, resistance to the effects of aqueous media and physiological solution) in the form of copolymers of methyl methacrylate with methyl acrylate (MA) or butyl acrylate (BA) with the brand names Dacryl-4B, Dacryl-2M and Dacryl-4M (4% BA; 2 and 4% MA respectively) having a molecular weight of around 105. For comparison, block polymethyl methacrylate with a molecular weight of 3 x 106 was used. The results of experiments on the ageing of unirradiated and irradiated specimens in a heated store-room (t = 10 - 200C) and at high temperatures (900C) are also given. It is shown that irradiation with doses of 2.5 - 20 Mrad leads to radiolysis of the above copolymers, accompanied by destructive processes. Evidence of this is an increase in the polydispersity of the materials and a reduction in their mean molecular weight. These changes impair their physicomechanical characteristics to some extent. Irradiation with a sterilizing dose of 2.5 Mrad reduces the strength indices by around 15%, which is quite acceptable for polymer products having high initial physicomechanical characteristics. Irradiation has practically no effect on the molecular and strength characteristics of Dacryl products in a heated room, and the change in physicomechanical properties resulting from storage at high temperatures is practically the same for unirradiated and irradiated specimens. On the basis of these results the materials investigated can be recommended for the packaging of medicinal preparations