Structure and properties of cellular thin-walled cable coatings

Abstract

The paper describes the manufacturing process of cable and conduit double-layered coatings by cellular co-extrusion method. This coatings were obtained using poly(vinyl chloride) (PVC) and 0-0.5 wt. % of Adcol-blow UP-0Xb+X1020 as a blowing agent. The density and porosity of the produced samples were investigated. On the basis of their results the usefulness of obtained coatings to insulate electrical cables was evaluated.

Calibrator device for the extrusion of cable coatings

“…In the process of extrusion of cable topcoats, the demanded shape and cross sectional dimensions are imposed by the extruder die, with consideration of the Barus effect and the phenomenon of shrinkage [2,3,5]. However, when high requirements are established with regard to the accuracy of shape and dimensions of the cross section, it is necessary to fix the shape and dimensions by means of calibration of the obtained extrudant.…”

“…Combined calibration is the combination of outside and inside calibration types, however it is hardly ever used [2,3,5]. Outside calibration means that after leaving the extruder die, the extrudant is led through a cooled calibration sleeve of a given diameter, a given length and having a determined pressure value ( Figure 2).…”

“…Inspection of selected physical, mechanical and usable properties of topcoats manufactured in the process of extrusion coating of cellular plastics, comprised part of a larger research project [1][2][3].…”

“…Technical University of Košice and Lublin University of Technology have developed a technological process for cellular extrusion of cable coatings, and as a result new coatings having different properties, such as reduced density (Figure 1). This results in the change of properties and features of cable coatings [1,3,7]. Calibration plays a significant role in the process of cellular extrusion.…”

“…During the inside cellular process, the external contours and dimensions are identical between the stages of leaving the extruder die and entering the calibration block. The intensity of cooling during calibration determines the thickness of the compact solid topcoat as no cells are formed during this process, whereas during the free cellular extrusion process, the period of cell growth is longer due to the larger distance between the head and the calibrator [3,4,7].…”