A Study of the Physicomechanical Properties of Plasticized Polyethylene Composites at Different Temperatures
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udy of the Physicomechanical Properties of Plasticized Polyethylene Composites at Different Temperatures E. S. Petukhovaa, * and A. L. Fedorova aInstitute
of Oil and Gas Problems, Siberian Branch, Russian Academy of Sciences, Yakutsk, 677980 Russia *e-mail: [email protected] Received February 19, 2019; revised March 20, 2019; accepted April 11, 2019
Abstract—Plasticized polyethylene composites are studied. It is established that adding dibutyl cebacinate to a polyethylene matrix provides growth of deformation characteristics of polyethylene at negative temperatures and its crack resistance due to satisfactory solubility of a plasticizer in the polymer matrix, which leads to an increase in segmental mobility of macromolecules and the formation of a homogeneous fine-spherulite supramolecular structure. Keywords: polyethylene, stearic acid, dibutyl cebacinate, physicomechanical characteristics, negative temperatures, crack resistance, supramolecular structure DOI: 10.1134/S1995421220040176
The existing regulatory documents for polyethylene pipes for gas and water piping systems have restrictions to temperatures of their transportation, installation, and operation [1–3]. For example, in designing a polyethylene gas piping system, it should be taken into account that, in the operation, the temperature of a pipe wall should not go below –15°C [1, 2]. The regulatory documents for polyethylene water pipes state that such systems are intended for water supply at a temperature from 0 to 40°C [3]. Despite the indicated temperature restrictions, polyethylene pipes are widely used in regions that are considered zones with cold or very cold climates according to the present classification, due to the clear technical–economical advantages compared to steel ones. The problem of maintaining temperature control for gas pipelines is solved by underground laying into permafrost ground, where the temperature does not go below –15°C at a depth of 1.5 m even in the northernmost regions; for water pipelines, this problem is solved by using them primarily for seasonal supply of water to the country areas.
When using pipes in household-drinking water supply systems, to avoid supercooling of a pipe wall, a continuous water flow is required in the winter period, with a temperature that is known not to go below 0°C in a liquid state. Despite the existing technical solutions that make it possibly to employ polyethylene pipes in regions with an ambient air temperature reaching a threshold of –50° and below, to reduce the probability of their destruction caused by accidental mechanical actions, it is required to increase such parameters of polyethylene (PE) as its deformation properties at low temperatures and crack resistance. These characteristics of polymeric material can be improved by adding plasticizers. Thus, the purpose of this work was to develop and study frost-resistant polyethylene composites for pipes using different plasticizers. As a polymer matrix, we used a pipe grade that is popular in Russia PE–PE2NT11 (PAO Kazanorgsintes).
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