The use of thermoplastic starch in compositions based on polylactic acid is of interest from the point of view of controlling the physicomechanical properties of materials and the time of biodegradation. The effect of thermoplastic starch containing sorbitol and / or glycerin as plasticizers on the resistance of compositions based on polylactic acid to thermal and thermomechanical action was studied. The physicomechanical properties of the compositions and their resistance to biodegradation under composting conditions have also been determined.
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.
Polylactic acid, due to such properties as biocompatibility, inertness to aggressive media of the human body and biodegradability is becoming more widespread in medicine, particularly in traumatology and reconstructive surgery. The article discusses modern developments in the field of biodegradable medical products based on polylactic acid that are already on the market or planned for production in the near future. Also considered the major major producers of polylactic acid.
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