Continuous Process for Recycling Silane Cross-Linked Polyethylene Using Supercritical Alcohol and Extruders

Abstract

In this study, we developed a continuous process using extruders in a pilot plant for recycling silane cross-linked polyethylene (silane-XLPE) via chemical reaction in supercritical alcohol. As a first step, an autoclave was employed to reveal the effects of temperature and pressure on the reaction that selectively decomposes the siloxane cross-linking bonds. Selective decomposition of the siloxane bond was found to occur in the supercritical alcohol. In the next step, an extruder was used to continuously feed silane-XLPE into a tube reactor containing supercritical alcohol. Silane-XLPE was then extruded with an injection of supercritical alcohol. Alcohol remained in the supercritical state inside the cylinders of the extruder and the tube reactor. The recycled polyethylene (PE) was continuously extruded from the reactor at a rate of 14 kg/h. The product produced by this continuous process was the same as that from the autoclave. The mechanical properties of the recycled PE satisfied the requirements for use as a wire and cable insulation material. These results suggest that the extruder proved to be useful for the continuous denaturation of a cross-linked polymer in supercritical alcohol.

Using Asphalt as an Additive for Waste Cross-Linked Polyethylene Recycled Materials to Improve Thermoplastic Processing

“…According to the literature, there are many methods for recycling waste XLPE, 9 including thermal shear plasticization recycling, 10 , 11 powdered filler recycling, supercritical fluid recycling, and ultrasonic-assisted recycling, 12 − 14 which have disadvantages of poor mechanical properties of materials, large equipment investment, and strict process requirements. 15 − 17 In order to recycle XLPE in a simple and efficient way, solid-state shear milling (S 3 M) technology was used.…”

The Novel Application of Asphalt in Cross-Linked Polyethylene Composite

“…According to literature, the recycling methods of XLPE include thermal shear plasticization recycling [10], powdered ller recycling, supercritical uid recycling, and ultrasonic-assisted recycling [11][12][13]. Above technology faced with defects of poor mechanical properties of materials, large equipment investment and strict process requirements [14][15][16].…”

Recycling of crosslinked high‐density polyethylene through compression molding

“…One of the recycling methods, studied by the majority of these studies, was on decrosslinking of XHDPE and XLDPE followed by shaping using compression molding, injection molding, and extrusion. Prior to shaping, the crosslinked polyethylene was decrosslinked using solid‐state shearing (milling), melt state shearing, supercritical fluids such as water, methanol, propanol, ethanol, and ultrasonic aided melt state shearing . These studies were concerned with evaluating the efficiency of the decrosslinking process, while the three shaping processes, identified above, were used to manufacture test coupons for evaluation of tensile mechanical properties of coupons made with the decrosslinked polyethylene in comparison to those coupons manufactured with the crosslinkable polyethylene (virgin) or polyethylene without any initiator.…”