Effect of Chemical Blowing Agent on the PVC Cellular Coating Extrusion

Depending on the type and application, the coatings of power, electric, telecommunication cables as well as other types of conduits are made of various kinds of polymer plastics. However, most often, because of good mechanical properties and many other advantages, they are first of all made from polyvinyl chlorine (PVC). This paper contains characteristics of the developed cellular extrusion of cable coatings, as well as specification of the blowing agent (BA) used and selected research results of the obtained cellular extrusion product. In technological tests the coating extrusion technological line was used. The material was modified with a new blowing agent of exothermic distribution of process characteristics, which was introduced into the material in quantities from 0.2 to 0.6% wt. The amount of blowing agent used has a direct impact on the density and structure of the received result for the extrusion of modified polymers. The cellular structure of the cellular coatings was presented. The results of the study are thin-walled properties of single- and double-layer cellular outer coatings, forming an outer surface on a steel wire. The research on the structure of manufactured materials, density and the degree of porosity, water and oil absorptivity, mechanical strength is presented.

Model of creation a multilayer structure for production of building pipes

A scientific article presents the main goals that can be achieved through the use of co-extrusion processing technology and equipment for the processing of secondary polymer and building materials. The main indicator of the multilayered product being created in the process of co-extrusion processing of secondary building and polymer materials is determined. The methods of quality control of the mixture preparation from secondary materials and quality of manufacturing of a finished co-extrusion product are considered. A reference mathematical model of a co-extruded product containing secondary building and polymer materials is constructed. Based on the results of the studies, the article presents an analysis of the ecological state of building and polymer wastes. The necessity of further research in the field of improving the model of the formation of a multilayer structure of a given quality for the process of processing this waste is substantiated. For the existing practice of preparing a mixture of polymer and building material wastes, the volumetric costs of components are determined by recipes. An analysis of the equations obtained allows us to refine the recommended numerical values of the percentage of primary polymer on the basis of the required standard strength of the building pipe from secondary materials.

THE INFLUENCE OF THE RECYCLED POLYMERIC MATERIALS VISCO-ELASTICITY ON THE PIPE EXTRUSION HEAD DESIGN

<p>There are summarized the experimental researches, previously performed, concerning viscous-elastic characteristics changes of PP due to recycling. There are presented, comparatively, the results for the virgin and 10 times recycled polypropylene. Using CAD-CAM it is studied the influence of the PP viscous-elastic characteristics changes due to recycling on the pipe extrusion head design, aiming to obtain a good extrusion product (expressed in the given case by the pipe dimensions stability). It resulted that it is compulsory to do experimental research to obtain the actual viscous-elastic properties of the polymer after many times recycles, because these properties affect significantly the output and the annular uniformity of the pipes thickness.</p>

The Influence of Modifying HDPE on Properties of the Surface

The aim of the paper was to discover the influence of modifying HDPE with selected agents that is a blowing agent, in the course of the extrusion process, inclusive of determination how the modification affects selected physical properties and properties of the surface of HDPE extrusion product. Endothermic chemical blowing agents in the amount of 0.6 % by mass were used in the research. The article presents selected results of examination of melt flow rate (MFR) and microscopic structure.

The Surface Heat Transfer Coefficient Model of 7075 Al-Alloy Extrusion Product and its Temperature Prediction

Surface heat transfer coefficient is a key parameter for accurately predicting the extrusion product temperature near the die exit and then achieving isothermal extrusion by speed controlling. Based on the heat transfer characteristics of extrusion product during cooling process, a dynamic loading method of heat transfer boundary conditions was proposed. The surface heat transfer coefficient model of 7075 Al-alloy extrusion product was established using the dynamic loading method and inverse calculation comprehensively. The model indicated the relationship among surface heat transfer coefficient h, surface temperature T and initial temperature T0 as h=1.16T-0.97T0. Its accuracy is high enough for calculating the surface temperature of 7075 Al-alloy extrusion product. According to the model and the experimental data, the relationship between the product and the measured temperatures can be established. It provides an effective way to solve the problem that the extrusion product temperature near the die exit cannot be directly measured.

Operating Parameters’ Influence on the Specific Volume of Extrusion Puffed Food

Twin-screw extruder is the main equipment for puffed food processing. Corn powder as the main raw material, barrel temperature, screw speed and feed rate of the extruder as the independent variables, specific volume of the extrusion product as the objective function, experiment has been carried out base on factorial design method. How the independent variables influence the objective function has been analyzed. Values of the operating parameters to get optimal specific volume has been gained.

Effects of Multi-Step Welding Chamber on Extrusion Product Quality and Die Strength

The shape of welding chamber is a key parameter in flat porthole die extrusion process, which influences product quality and die life-span directly. In this paper, by means of numerical simulation of the extrusion process for an aluminum hollow profile, the effects of multi-step welding chamber on metal flow and die strength have been investigate. The numerical results revealed that the multi-step welding chamber was effective to balance metal flow in the die cavity. In addition, with an increasing step of welding chamber, the maximum stress and deflection of the lower die decreased, while the deflection of the mandrel kept almost unchanged and the maximum stress of upper die increased.