STUDY OF THE EFFECT OF TECHNOLOGICAL PARAMETERS OF ROTARY MOLDING ON THE WETTING EDGE ANGLE

This article presents a study of the problem of polyethylene re-utilization (its secondary processing – recycling) by rotational molding. In scientific literature, recycling of rotational grades of polyethylene (RPE) is very poorly studied, and the data presented are often contradictory. However, for the production of containers by rotational molding, using secondary polyethylene in industry, it is necessary to take into account its degradation (occurring under recycling conditions), for the assessment of which the authors used the following methods: IR spectroscopy, atomic force microscopy, study of the hydrophobicity of the RPE surface (by measuring the contact angle (CAA)) and mechanical tests. In view of the widespread use of these containers (for storing mineral fertilizer, grade KAS28), the CAA of RPE with distilled water (after exposure to KAS28) was studied under various technological modes of their processing (PIAT indicator). It is shown that recycling of RPE leads to the formation of carboxyl groups on the surface of polyethylene and a significant increase in its hydrophilicity (the contact angle decreased to 36%). Keeping KAS28 also increases the hydrophilicity of products made of secondary and primary RPE (reduction in the contact angle from 8% to 28%) regardless of the processing parameters considered. It is shown that the most influential factor (of those studied) on the hydrophilicity of RPE is recycling. It was found that at a dosage of up to 15-25% of secondary polyethylene in composites, only minor changes in the strength characteristics (tensile strength and deformation) are observed, which allows us to recommend partial substitution of primary raw materials without critical losses in performance properties (with secondary polyethylene). This opens prospects for the economically feasible use of secondary PE in the production of rotational composites. This study can be used to assess the degradation of RPE during its recycling and improve the performance properties of finished products.

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