Comparative Analysis of the Structure and Properties of Polyethylenes Crosslinked by Different Methods

Abstract

Currently, in the installation of the engineering systems of buildings and constructions, crosslinked polyethylenes (PEXs) are widely used for the cold and hot water supply and heating system piping. The world consumption of crosslinked polyethylenes for these purposes amounts to 55% and is continuing to grow (Figure 1). Crosslinked polyethylenes are produced by peroxide (PEXa), silanol (PEX-b), or radiation (PEX-c) methods [1-6].

Modifying the Properties of Chemically Crosslinked Polyethylene with Thermoplastic Elastomers

“…• Crosslinking agents have a considerable effect on the nature of interchain bonds, the packing density in the amorphous zones of polyethylene (PE), and accordingly its entire combination of physicomechanical and relaxation properties [1]. Crosslinks between linear molecules of peroxide-and radiation-crosslinked polyethylene consist of =C-C= groups, and in the case of silanol crosslinking they consist of =Si-O-Si= bonds.…”

“…The chemical crosslinking of PE has recently been actively used to produce heat-resistant polymeric materials, especially for pipes, because articles of crosslinked polyethylene possess higher strength characteristics and thermophysical properties. Silanol crosslinking is widely used in the production of polymer pipes, because, when produced by this method, the material possesses higher thermophysical properties than polyethylene crosslinked by other methods [1]. Articles of silanol-crosslinked polyethylene are uncompetitive on the materials market because of their cost.…”

“…Because of the reduction in network density, there is an increase in the mobility of the macromolecules, and therefore, with increase in the content of pure polyethylene, the elongation at break of the composites increases. However, it must be noted that the combination of relaxation and strength characteristics is influenced considerably not only by the network density but also by the nature of the crosslinked points, the fragments between the crosslinked points, and their kinetic flexibility [1].…”

Orientational Elongation of Silanol-Crosslinked Polyethylene Films

“…Silanol crosslinking can improve the properties of polymeric materials signifi cantly [1][2][3], including the properties of oriented heat shrink fi lms [4,5]. It is known that preliminary crosslinking provides polyethylene fi lms with high and stable thermal shrinkage and shrinkage stresses.…”