Silane cross-linked polyethylene cable material is widely used in my country's wire and cable industry as an insulating material for low-voltage power cables. Compared with peroxide cross-linking and irradiation cross-linking, this material has the advantages of simple manufacturing equipment, convenient operation and low comprehensive cost in the manufacture of cross-linked wires and cables, and has become the leading insulation for low-voltage cross-linked cables. Material.

Silane cross-linked polyethylene mainly has two processes, that is, grafting and cross-linking. During the grafting process: under the action of the free initiator and the free radical formed by pyrolysis, the polymer loses the H atom on the tertiary carbon atom to generate a free radical, which reacts with the -CH=CH2 group of vinylsilane to generate Grafted polymers containing trioxysilyl ester groups. During the cross-linking process: the grafted polymer is first hydrolyzed under the action of water to generate silanol, and -OH condenses with the adjacent Si-O-H groups to form Si-O-Si bonds, thereby making the polymer macromolecular intermolecular. Cross-linking occurs.

Silane coupling agent can improve tensile and breaking strength, chemical resistance, scratch resistance and memory effect in silane crosslinking material. The amount of silane coupling agent added is generally controlled at 1%-2%.

Silane can increase the connection between molecules and make the molecular chain less prone to relative slippage. At the same time, the increase of polar groups hinders the movement of the chain segments, so that forced high elasticity cannot be achieved, so the tensile strength of XLPE is improved. Excessive cross-linking tends to reduce the crystallinity of the polymer, or the tendency to crystallize, thus reducing the tensile strength of XLPE and increasing the elongation at break. Therefore, with the increase of the amount of coupling agent, the tensile strength gradually increased. After increasing to a certain extent, it showed a downward trend. The elongation at break decreased with the increase of the amount of silane coupling agent. When the dosage is too large, the elongation at break increases instead.

After PE cross-linking, due to the increase of polar groups, the degree of branching of the molecular chain increases, the distance between molecules increases, the force becomes smaller, and the impact strength increases. When the degree of cross-linking is too high, the polar groups If it is too dense, the movement of the chain segment is hindered, so that the forced high elasticity cannot be achieved, and the impact strength decreases instead. Therefore, with the increase of the amount of coupling agent, the impact strength increases. When the amount of coupling agent was too large, the impact strength showed a downward trend.

Therefore, the addition amount of silane coupling agent in silane cross-linked cable material is generally controlled at 1%-2% to achieve good results.