Shigeru Tokuda, Sanae Horikawa, Kunio Negishi, Kenji Uesugi and Hiroshi Hirukawa
Because of its outstanding dielectric properties and heat resistance, crosslinked polyethylene (XLPE) is widely used as insulation materials for electric wires and cables. However the three-dimensional lattice structure produced by crosslinking makes it impossible to melt it down again for molding. Thus almost all waste XLPE is currently burnt (as a fuel) or disposed of in landfills. In this work the authors have developed technology in which the application of suitable heating and shearing to XLPE decreases its molecular weight, producing a recycled material that is sufficiently thermoplastic to allow it to be molded, and have evaluated the physical properties of the recycled material obtained. The crosslinked content remaining in the recycled material is from about 1 to 40 %; the melt flow rate (MFR) is in the range of 0.1 to 30 g/10 min, and the chemical structure is substantially the same as the original material, making it possible to recycle it to various applications using ordinary molding equipment.