Engineering thermoplastics, in particular polyolefins such as special grades of high density polyethylene, are gaining importance in high pressure pipe applications such as gas and water supply systems. To ensure proper performance of such pipes over the required lifetime, durability analyses are needed to adequately account for the effects of loading, time, temperature, and especially the occurrence of defect particles in the pipe, such as gel particles, contaminants, process residues etc. The objectives of this work are to characterize the defect particles in HDPE pipes, examine their origins, and correlate with the long-term performance of pipes. The results indicate that the lifetime of these pipes under hydrostatic test conditions may be more sensitive to the rigidity and interfacial adhesion of defect particles than purely the size of defect particles.
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