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This article is devoted to a study of the effect of ultrasound treatment of melts of polymer blends on their rheological properties during repeated processing, to establish the possibility of the combined processing of polymer waste of different chemical nature. The intense development of the production of polymer composites requires the development of new, nonstandard methods for their modification that may be used under modern conditions of development of science and technology.

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The problems of safe use of packaging for contact with food are discussed. In particular, the possibility of migration of low molecular weight chemicals from packaging materials to a consumer product, which above a certain established threshold value, represents a significant risk, has been investigated. Particular attention is paid to packaging that contains recycled materials. The problems that need to be solved for the safe use of recycled materials in packaging are discussed. An example of the use of polyethylene terephthalate (PET), which has passed the stages of controlled aging in mechanical recycling, is considered. The change in the microstructure of the polymer from cycle to cycle, its chemical composition and physical parameters were assessed by methods: physico-mechanical, optical and electron microscopy with X-ray microanalysis, FT-IR spectroscopy, viscosity (melt flow rate), biotesting. A noticeable effect of the aging process on both the original primary polymer and the recycled one is shown. Moreover, the biotesting method revealed sufficient toxicity of both secondary PET, which has a certificate, and PET flakes. As the oxo-degradable packaging, two samples of industrial polymer packaging were chosen, which contained different oxo-degradable additives: d2w and "REVERTE". The ciliates Tetrahymena pyriformis were used as test objects. Research has shown that a declared supplement can only be a declaration. The analysis of the microstructure and chemical composition of the films by X-ray diffraction microanalysis revealed the absence of transition metal ions. The test objects of the ciliates behaved practically the same in control solutions and in the presence of the studied films with the d2w oxo additive, which reliably indicates the absence of these additives in the films. The prospects of using the methods of biotesting of packaging materials have been proved as they allow, without the use of model environments and sanitary-chemical studies, to give a relatively quick conclusion about the safety of the material and its suitability for contact with food.