Generalization of the Temperature Dependence of Some Physical Properties of High-strength Polyethylene (HDPE) Using the Method of Given Parameters

Shixaliyev Kerem Sefi

doi:10.11648/j.ajche.20190706.11

Abstract

In this paper, based on the study of HDPE by dilatometric and rheological methods in a wide range of temperatures and cooling and deformation rates, we generalized the temperature dependence of the physical properties of polyethylene using the specified parameters method. Test specimens (cylinder size: height 12 mm, diameter 9.3 mm) were obtained both in the dilatometer’s test cylinder itself and in a specially designed injection mold using injection molding on a TP-125 injection molding machineThe temperatures in the experiments were added and maintained with an accuracy of 3.2.°C. Defined by The dependence of ρ_0 T_0 / ρT (relative reduced density of the polymer) on the reduced temperature (T - T0). Test specimens (cylinder size: height 12 mm, diameter 9.3 mm) were obtained both in the dilatometer’s test cylinder itself and in a specially designed injection mold using injection molding on a TP-125 injection molding machine. It was found that a reliable characteristic of the dilatometric properties of the crystallizing polymer, physically correctly and completely reflecting the features of the crystalline structure, can be obtained only in the mode of stepwise temperature changes, when at each given temperature the equilibrium value of the specific sample of the primer is fixedThus, the practical value of the dilatometric method for studying crystallizing polymers is shown, especially when comparing the results of dilatometry with the results of rheological studies.

Highlights

HDPE, obtained by polymerization at moderate pressures, is characterized by high linearity of macromolecules, narrow MMD and a high degree of crystallinity
It was found that a reliable characteristic of the dilatometric properties of a crystallizing polymer, which physically correctly and fully reflects the features of the crystalline structure, can be obtained only in a step-change mode, when the equilibrium specific volume is fixed at each given temperature polymer sample
The calculation of the primary results of dilatometric measurements was carried out according to an improved method, which allows taking into account the change in the diameter of the sample studied in Shixaliyev Kerem Sefi: Generalization of the Temperature Dependence of Some Physical Properties of High-strength

Summary

Introduction

HDPE, obtained by polymerization at moderate pressures, is characterized by high linearity of macromolecules, narrow MMD and a high degree of crystallinity. These features of the chemical and physical structure of HDPE must be taken into account when studying their behavior at high temperatures (in the molten state), as well as during the processing and operation of the products obtained from them. It was found that a reliable characteristic of the dilatometric properties of a crystallizing polymer, which physically correctly and fully reflects the features of the crystalline structure, can be obtained only in a step-change mode, when the equilibrium specific volume is fixed at each given temperature polymer sample. Polyethylene (HDPE) Using the Method of Given Parameters the dilatometer, which is associated with the actual shrinkage of polyethylene

Method

Result

Discusion

Conclusion