The physical properties of cross-linked polyethylene cables are significantly changed after being cross-linked by silane.
Since the cross-linked polyethylene cable is a macromolecule, it is infusible and insoluble, and the heat resistance is significantly improved.
Low cross-linking degree, Vicat softening point changes little; high cross-linking degree, Vicat softening point can be increased by 30 ℃ ~ 40 ℃; long-term use temperature of cross-linked polyethylene cable is 95 ℃ ~ 100 ℃.
The cross-linked polyethylene cable with a molecular weight of 200,000 has only 12 to 13 silane monomers connected to each molecular chain, so the distance between the cross-linking points of the Silane Crosslinking LSZH cable is large. The flexibility of the si-c-bond is good, so the cross-linked polyethylene cable has good low temperature resistance and can be used at -50°C or even -70°C.
In addition, because the molecular structure of silane cross-linked polyethylene cable is different from the intermolecular -c-c-crosslinking bond usually formed by peroxide crosslinking, its three siloxy groups can undergo hydrolysis and condensation reaction, which can form a three-dimensional network crosslinking. Therefore, its thermomechanical properties are generally better than those of peroxide-crosslinked polyethylene cables with a -c-c-planar structure.
Even if the crosslinking degree of silane crosslinked polyethylene cable is 15%~20% lower than that of peroxide crosslinking, the heat distortion temperature of the two is still comparable.
cross-linked polyethylene cables have better chemical resistance than ordinary cross-linked polyethylene cables. On the one hand, the strength is improved after cross-linking. The long chains continuously enter the tightly packed platelet lattice, thus increasing the number of linking molecules between the crystals. In addition, the long-chain branch entanglement in the cross linked polyethylene structure strengthens the amorphous region between the wafers and improves the environmental stress resistance, especially at 100°C. ℃ below the higher temperature range.
The cross-linked polyethylene cable has fewer crystalline areas, uniform density, and the introduction of non-polar -si-o-bonds and -si-c-bonds, making its electrical insulation basically unchanged, so it is still a good insulating material. And the insulation is still high at higher temperatures and harsh chemical media, and is often used for cable shielding.