While producing polymers as well as during their processing, a certain amount of stabilizers is introduced into the product, which should ensure polymer properties saving during processing and those of polymer products during storage and operation. However, in cases where medical products based on polypropylene are subjected to radiation sterilization, there are not enough stabilizers in it to save their characteristics during operation. In this regard, we made an assessment of the influence of processing conditions on the properties of polypropylene with a different set of stabilizers in the manufacture of products based on it, in order to assess the degree of influence of each technological operation, including the effects of ionizing radiation during sterilization. Processing and radiation exposure are shown to affect the properties of polypropylene. Nevertheless, the effect of ionizing radiation with an absorbed dose of 40-60 kGy exceeds the negative effect of thermo-oxidative breakdown greatly during the extrusion of PP. Polypropylene containing organophosphorus stabilizers (brand PP 1562R) is more susceptible to breakdown. This is indicated by low values of oxidation induction time, breakdown initial temperature, as well as high values of MFI after exposure to electron radiation. PP brand PP H350FF/1 whose stabilizing complex contains phenol-phosphite antioxidants is more resistant to breakdown during processing and sterilization. For both brands under study, it is apparently necessary to increase the content of stabilizing additives in order to save the properties at the level of the original unexposed material.
Non-woven materials are widely used for the manufacture of disposable medical clothing and underwear. Radiation is widely used to sterilize single-use medical devices. The paper analyzes the effect of ionizing radiation at absorbed doses of 0-60 kGy on the stress-strain properties of medical non-woven spanmelt material based on polypropylene obtained by blow-molding technology. It has been established that ionizing radiation significantly reduces the breaking load and elongation in the machine and cross directions of the web. For this type of material, the most critical is the decrease in strength in the cross direction of the web, primarily because the level of strength in the cross direction of spanmelt materials is generally low. Sterilization by ionizing radiation further reduces strength and leads to the fact that non-woven materials irradiated with an absorbed dose of 50-60 kGy are close to unacceptable values in accordance with the requirements of EN 13975-2011.
The production of nonwovens over the past few years remains one of the most promising areas in the textile industry. This is due to the short cycle of production of such materials from raw materials to finished products and the ability to produce at a low cost a wide range of materials for both household and technical use. In particular, non-woven materials are widely used for the manufacture of disposable medical clothing and underwear. An important characteristic for surgical clothing is an indicator of bursting strength. This study simulates material deformation similar to elbow pressure when bending the arms or knee when bending the legs. Since the lower part of the sleeve of the product refers to the critical zone of the product, i.e. to the zone most likely to be involved in the transfer of infectious pathogens to or from the wound, the sterile product must have a significant margin of bursting strength. The effect of the absorbed dose of electronic radiation on the strength during the bursting strength of nonwoven medical material of SMS design with a surface density of 35 and 50 g/m2 obtained using the spanmelt technology was studied. It is shown that electronic radiation significantly reduces the resistance of the nonwoven to bursting strength. With an absorbed dose of 40 kGy, the material no longer meets the requirements for surgical clothing and linen by regulatory documents. For non-woven materials obtained using spanmelt technology, the bursting strength rate is even more sensitive to the action of ionizing radiation than the tensile tensile load, therefore, this indicator is recommended to be used as a characteristic indicator of radiation resistance.
For polymeric materials intended for the manufacture of disposable sterile medical devices, resistance to sterilization methods is important. For the manufacture of disposable medical products is widely used polypropylene, destructive during radiation sterilization. It is established that the addition of polyquinone leads to a decrease in the destruction of polypropylene, which is manifested in a decrease in the values of the melt flow index and an increase in the degradation temperature of polypropylene of the irradiated compositions.
Using optical and atomic-force microscopy methods, it has been established that exposure to electron radiation causes a change in the supramolecular structure of polypropylene – in films obtained by recrystallization of irradiated polypropylene, spherulites have a less perfect shape than films obtained from unirradiated polypropylene. Also, the films obtained by recrystallization of irradiated polypropylene surface roughness is greater.
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