Thermal properties of polymer compounds based on recycled polypropylene and polyethylene

The relevance of the problem under study is due to an increase in the amount of polymer waste based on synthetic polymers, which determines the feasibility of its involvement in recycling in relation to thermoplastic polyolefins. A significant proportion of plastic waste falls on plastic products made of polypropylene, while the processed raw materials almost always contain a mixture of polypropylene with different polyethylene content. The aim of the work was to study the thermal characteristics of polymer compounds based on secondary polypropylene filled with high and low pressure polyethylene. The leading approach to the study of this problem is the use of methods of thermogravimetry and differential scanning calorimetry, which make it possible to identify patterns of changes in temperature and thermal characteristics of phase transitions, as well as thermal stability of polymer compounds. It is shown that the presence of two peaks of melting and crystallization on thermograms of differential scanning calorimetry of polypropylene-polyethylene mixtures indicates the incompatibility of polymers, while the polymer system is heterophase. in the presence of polyethylene, the crystallization rate of polypropylene changes, while its melting temperature decreases and the crystallization temperature increases compared to a pure polymer. Filling the compound with polyethylene of both low and high pressure reduces the rate of decomposition of secondary polypropylene and shifts the decomposition process of compounds to higher temperatures. The mass of the dry residue when heated to 400 degrees C and 600 degrees C for a polymer compound with low-pressure polyethylene is higher compared to high-pressure polyethylene. The materials of the article can be useful for the creation of polymer composites based on recycled polypropylene in the presence of polyethylene, as well as the development of technological modes of their processing.