STUDY OF THE INFLUENCE OF HDPE AND UHMWPE ON THE PROPERTIES OF ETHYLENE PROPYLENE DIENE VULCANIZATES

Introduction of small additives of thermoplastic polymer into the elastomer matrix is one of the simple and effective ways to improve the complex of physical and mechanical properties of rubbers. This article is devoted to the study of the effect of low-density polyethylene (HDPE) grade 273-83 and ultra-high molecular weight polyethylene (UHMWPE) grade GUR 4113 on the vulcanization characteristics of rubber compounds, physical and mechanical properties and resistance to thermal aging of vulcanizates based on ethylene propylene diene rubber grades SKEP-40 and SKEP-50. The use of HDPE and UHMWPE as additives is of interest not only due to their properties, but also due to their similar chemical nature to SKEP. It is shown that the introduction of polyethylene additives leads to some increase in the duration of the rubber compounds in the viscous flow state and the vulcanization optimum. Vulcanizates containing polyethylene additives are charac-terized by an increase in the conventional stress at 100 % elongation and a decrease in the relative elongation at break, which indicates an increase in the rigidity of the vulcanizates. In the presence of PE, wear resistance and the ability to elastic-elastic recovery of vulcanizates after compression also increase significantly. The frost resistance coefficient of rubber samples containing UHMWPE remains at the level of the original vulcanizates, and in the case of HDPE it decreases significantly, which can be explained by the better ability of UHMWPE to maintain its flexibility at low temperatures. According to the results of accelerated thermal aging, it was found that the presence of polyethylene additives leads to a significant increase in the stability of the elastic-strength properties of vulcanizates based on SKEP-50. Moreover, the higher the molecular weight of polyethylene, the higher its efficiency. It should be noted that in the DOT-4 environment, vulcanizates are characterized by a greater degree of preservation of elastic-strength indicators compared to the air environment, which is due to their high resistance to this working environment. It was found that UHMWPE, compared to HDPE, results in the production of an elastomeric material based on EPDM with a more optimal set of physical and mechanical properties and increased stability of elastic strength indicators after thermal aging.