Rapid fracture resistance of polyethylene: dependence on polymer structure

Polymer pipe materials being widely used in the industry for transport purposes introduced new areas of research from mechanics of materials perspective. In this study the effect of structural parameters on the fracture resistance of polyethylene pipe material have been investigated via testing materials differing in their overall structure, density, crystallinity, molecular weight, and carbon black by performing S4 tests in addition to Instrumented Charpy, Reversed Charpy and Tensile Tests. Furthermore, the effect of extrusion conditions have been investigated via performing S4 Tests on pipes having differing process histories. A new technique of analysing tensile testing enlightening plane stress resistance is demonstrated. The stability of adiabatic drawing in a tensile test is found to be related to the plane stress fracture resistance, which forms the basis of the RCP resistance of a pipe. This proposed method enables the use of two basic material properties – yield stress and strain hardening modulus – for ranking of the pipes RCP performances, making the idea of tailor-made pipes possible