Abstract:

Polyethylene with raised temperature resistance （PERT） was modified through micro⁃crosslinking to obtain a new type of cross⁃linked thermoplastic polyethylene （TPEXa） pipes. The resultant PERT pipe not only retained good thermoplasticity but also obtained an improvement in heat resistance and creep resistance due to partial crosslinking in the PEX pipes. The influence of the content of crosslinking agent on the melt mass⁃flow rate and crosslinking degree of TPEXa material was investigated， and the hydrostatic properties， hot melt recovery performance， and mechanical properties of the recycled TPEXa pipe material were characterized. The results indicated that the TPEXa material obtained a melt mass⁃flow rate of 5.6 g/10 min （190 ºC， 21.6 kg）， a crosslinking degree of 2.3 %， and a heat deformation temperature of 78 ºC （Tf0.45） at a crosslinking agent content of 0.08 wt%. The prepared pipe passed 22 h， 165 h and 1000 h hydrostatic tests at 95 ºC. The ring stress applied in the tests exceeded the requirements of the ring stress of PERT II pipe and was close to the ring stress of PEX pipes. The TPEXa material exhibits good temperature resistance and creep resistance. This material can be melted and recycled， and the recycled material presents good mechanical properties.

Key words: cross?linked thermoplastic polyethylene pipe, thermoplasticity, heat resistance, creep resistance, mechanical property