Crosslinked polyethylene: A review on the crosslinking techniques, manufacturing methods, applications, and recycling

Abstract

One of the most used resins in the plastics industry is polyethylene (PE).Although PE has good impact resistance and ductility, its low maximum use temperature and mechanical strength limit some commercial development, especially for load-bearing applications. To get better overall performances, crosslinking is performed to improve the chemical, mechanical, and thermal properties of PE. Although PE can be crosslinked by using various chemical and physical methods, this makes the resulting polymers more difficult to recycle since a three-dimensional (3D) network is created. In this review, we first describe the different crosslinking techniques for PE to manufacture crosslinked PE (XLPE) parts. Then, as more than half of the XLPE-based products are disposed directly after use, we present several options to reuse and recycle these products to overcome this environmental issue and find a sustainable solution. A focus is made on mechanical recycling and de-crosslinking techniques for XLPE to generate recycled-XLPE (r-XLPE). Finally, a conclusion is presented on the current situation and research gaps that must be filled by future works.

The Effect of Synthetic Polymer Foams on Cellulosic Material Degradation

“…As a result of the cross-linking process, the degree of crystallinity of PE decreases. Therefore, the properties associated with the degree of crystallinity (e.g., modulus of elasticity and hardness) are lower compared to non-cross-linked polyethylene [ 1 , 2 ]. Polymeric foams represent a two-phase system in which a gas is dispersed in a solid plastic.…”

“…The melt pressed into the desired shape of the product is then cross-linked, and after that, the cross-linked product is exposed to a temperature at which the blowing agent is decomposed. Azodicarbonamide is used as the blowing agent; its decomposition temperature of approximately 200 °C can be reduced with admixtures [ 1 , 2 , 3 , 4 , 5 ].…”

Effect of cross‐linking on the mechanical properties, degree of crystallinity and thermal stability of polyethylene vitrimers

“…Cross‐linked polyethylene (XLPE) consists of PE that has been either physically or chemically cross‐linked to form permanent covalent bonds linking adjacent chains. [ 3 ] The presence of the cross‐links leads to enhanced properties which give it an advantage in performance. Some common applications of XLPE include pipes and insulation for high voltage cables.…”

“…[ 4,5 ] However, the permanent covalent bonds lead to inferior processability which makes recycling and reusing of XLPE more difficult compared to PE. [ 3,6,7 ]…”

Fascinating flame resistance of polycaprolactam copolymer containing d‐glucopyranose for melt‐spun flame retardant fibers

“…One is to add flame retardant to PA6 composite fiber, but it will bring about problems of large amount of flame retardant, uneven dispersion, and poor spinnability, resulting in strength reduction, and so on. [6,7] Second, during the polymerization of PA6, the flame retardant is used as a reactive monomer to connect with the main chain or side chain of PA6, thereby giving PA6 flame retardant properties, which have the advantages of good stability, long-lasting flame retardant, and less impact on the material itself. [8] Gongxun Zhai and Lili Li contributed equally to this work.…”