Causes of PE Sheath Cracking

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Polyethylene (PE) is widely used for insulation and sheathing of power cables because of its good mechanical strength, toughness, heat resistance, insulation and chemical stability. However, due to the structure of PE itself, it has poor environmental stress cracking resistance, especially when PE is used as the outer sheath of armored cables with large cross-section, the cracking problem is especially prominent.

Mechanism of PE sheath cracking

PE sheath cracking mainly has the following two cases: one is the environmental stress cracking, refers to the cable after installation and operation, the sheath in the combination of the role of stress or environmental media contact, from the surface of the brittle cracking phenomenon. 

This cracking is generally caused by two factors: one is the presence of internal stress in the sheath, and the other is the cable sheath has been in contact with polar liquids for a long time. This cracking mainly depends on the material itself to resist environmental stress cracking performance, through years of material modification research this situation has been fundamentally solved. The other is mechanical stress cracking, because the cable in the structure of the shortcomings or sheath extrusion process is not appropriate, the sheath in the structure of a large stress, and easy to produce stress concentration. So that the cable in the construction of cable release deformation and cracking. This kind of cracking is more obvious in the outer sheath of steel belt armored layer with large cross-section.

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