Plastics in the Public Utilities

It is clear that there is a sharp time-dependent change in ageing behaviour that changes with test temperature and similar results have been found with LLDPE. It is not possible to predict with certainty from accelerated tests how long it will take for this change to occur at 20 °C and what will be the subsequent rate of change. It seems possible that discontinuity in the curves corresponds to the depletion of the antioxidants in the pipe, which may be due to physical as well as 

Plastics are also now used as a replacement for concrete in underground chambers. The performance of chambers is much less critical than that of pipes since they are not under pressure and can be readily replaced when necessary. Increasingly, recycled polyolefins are being used in this kind of application, which is a particularly appropriate second use for mixed thermoplastic polymers that are not exposed to UV light (Chapter 4, page 86). 

HDPE is the preferred material of construction for underground high integrity containers but these have been used for only about 20 years and there must be considerable doubt about their ability to resist the effects of high energy radiation in the presence of air over the next 20 years. 

Polyolefins are now being used increasingly in underground electricity transmission. Although not normally called geosynthetics in this application, the same durability characteristics are essential here. One of 

The initial mechanical properties of XLPE are exceptionally suitable for electrical cable. Because it is cross-linked, it will withstand relatively high temperatures without undergoing creep while at the same time it remains tough and resistant to fracture at relatively low temperatures. 

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