Effect of Processing and Radiation Exposure on the Structure and Properties of Polypropylene

Abstract

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.

Stability assessment of a commercial polypropylene copolymer and Irgafos 168 under repeated injection molding and γ‐irradiation cycles

“…Lisanevich et al investigated a suitable stabilization system in order to reduce radiation‐induced degradation of PP. According to them, PP stabilized with phosphitic antioxidants, such as Irgafos 168, in combination with phenolic antioxidants is most resistant to processing and sterilization‐induced degradation 5 . The result of the analyses of Kagiya et al states the importance of the amorphous components regarding the radiation stability of PP.…”

“…According to them, PP stabilized with phosphitic antioxidants, such as Irgafos 168, in combination with phenolic antioxidants is most resistant to processing and sterilization-induced degradation. 5 The result of the analyses of Kagiya et al states the importance of the amorphous components regarding the radiation stability of PP. As the degradation takes place exclusively in the amorphous regions, degradation is enhanced for less crystalline PP.…”

Study of the Properties of Compositions Based on Polylactic Acid and Thermoplastic Starch

“…An example is food waste containers, which are more convenient to throw away with their contents. Or, for example, disposable nonwoven products for hygiene (diapers, feminine hygiene products, napkins for various purposes) are also difficult to recycle and, as a rule, are only disposed of [13][14][15][16].…”

Influence of Gamma and Electron Radiation on the Strength Characteristics of Nonwoven SMS Materials Based on Polypropylene

“…An example of such a polymeric material is polypropylene. Due to its structure (the presence of a tertiary carbon atom), the polymer chain of polypropylene, when irradiated with ionizing radiation, degrades by a radical mechanism [8][9][10][11][12][13][14].…”