Accession Number:

ADP000574

Title:

Investigation of Premature Depletion of Stabilisers from Solid Polyethylene Insulation,

Descriptive Note:

Corporate Author:

TELECOM AUSTRALIA MELBOURNE

Personal Author(s):

Report Date:

1982-11-01

Pagination or Media Count:

13.0

Abstract:

Early failure of solid polyethylene insulation jointed in above ground closures is a serious field problem in Australia in cables made between 1965-74. Analysis has confirmed thermal oxidation as the cause, resulting from inadequate initial stabilisation and rapid depletion of antioxidant in service. No failures have been reported in more recent insulation incorporating the current primary antioxidantmetal deactivator systems, as used in many other countries. However, these systems are also depleted prematurely, and current polymers are unlikely to provide the expected life. Several factors cause this depletion of stabilisers, including rapid migration to the polymer surface due to insolubility at all service and polymer storage temperatures, substantial extrusion losses, elevated service temperatures and reaction with colourants. The use of secondary antioxidant appears beneficial, and triple component stabilisation systems, with components shown for their excellent solubility and oxidative stability, are being evaluated. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE