No abstract

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.

This study aimed at investigating the dependence of the ultrasonic (US) effects on the structure and properties of the polymer mixtures with different viscosity values. It should be noted that in the current study, polypropylene and high-pressure polyethylene of different brands were selected. The polymer composite materials (PCM) of various compositions treated with and without ultrasound were used. The formation dependence of the phase structures of polyolefin compositions on composition and viscosity of polymer systems was established. The regularity "structure-properties" of modified mixtures of polyolefins was determined. The influence of ultrasonic on the restoration process of the structure and the formation of new chemical bonds in polyolefin mixtures was discussed. The structure of the compositions of the polymer and technological conditions for their processing, which providing high physical and mechanical characteristics of PCM, were also proposed. The results indicated that to create compositions with high physical and mechanical characteristics, it is recommended to use a mixture of polyolefins containing 70% PE, modified by ultrasonic treatment.

The research features a comprehensive study aimed at increasing the technological compatibility of multilayer packaging materials. The paper describes a recycling technology with the prospect of returning the resulting secondary raw materials to the production cycle. The research included the following tasks: to conduct a comprehensive study of polyolefin mixtures modified by ethylene propylene copolymer; to study the effect of the copolymer on the rheological and physicomechanical properties of polymer compositions; to propose a technology for the recycling of secondary polyolefin mixtures. The research involved the following methods: the capillary viscometry method was used to determine the rheological properties of polymer compositions; the tensile test method was employed to define the physicomechanical properties of the compositions; the pycnometric method was used to assess the density of the mixtures. The study featured such polymers as polyethylene, polypropylene, and ethylene-propylene copolymer, which was chosen as a link between the polymers. The authors obtained polymer compositions in various ratios of polyethylene, polypropylene, and ethylene-propylene copolymer: 70:30:0; 68.5:28.5:3; 65:25:10; 30:70:0; 28.5: 68.5: 3; 25:65:10. The article describes the process of modifying polyolefin compositions based on polyethylene and polypropylene by ethylene-propylene copolymer on a single-screw extruder. The authors defined the rheological properties and the deformation-strength characteristics of the polymer mixtures. Repeated processing proved to lead to a decrease in the physicomechanical properties of polyolefin mixtures, with the exception of compositions based on polyethylene and polypropylene in the ratio of 30:70, where the breaking stress increased. The number of processing cycles increased the melt flow rate of the mixtures. The proposed technology is meant for producing multilayer packaging materials using packaging waste in the middle layer for contact with food.