The physical properties of polyethylene, the material used in gas distribution pipes and fittings, are ultimately determined by the nature of the polymer molecules in the resin used for pipe manufacture. This relation between molecular structure and properties is based on the morphology formed in the polyethylene by a particular processing history. Model polyethylenes having a very narrow molecular weight distributions and well defined levels of short chain branching and long chain branching have been used to quantify the effects of mechanical behavior, especially those related to fracture. Tensile deformation of unnotched and notched samples was done to assesses the relevant tensile and fracture toughness parameters. It has been demonstrated that a critical molecular weight is required for the attainment of good ductility and fracture toughness. This critical molecular weight is increased by the presence of short and long chain branches. The J-Integral fracture toughness increases by a factor of 2.5 over the molecular weight range (M = 40000 - 100000) where tensile ductility is achieved. Those polymers with high strain hardening rates resist deformation due to stress concentration at crack tips and thus display increased fracture toughness.
Structural basis of the mechanical properties of polyethylenes
Strukturbasis fuer die mechanischen Eigenschaften von Polyethylenen
US Government Reports ; Sep ; 1-40
1984
40 Seiten
Report
English
ROHRLEITUNG , ARMATUR , KUNSTSTOFFROHR , GASVERSORGUNG , POLYETHYLEN , PHYSIKALISCHE EIGENSCHAFT , MOLEKULARSTRUKTUR , MOLEKULARGEWICHT , VERNETZUNG , MECHANISCHE EIGENSCHAFT , DUKTILITAET , BRUCHZAEHIGKEIT , SPANNUNGSINTENSITAETSFAKTOR , VERSUCHSAUFBAU , PROBE , SPANNUNGSRISS , ZERSTOERENDE WERKSTOFFPRUEFUNG
The investigation of mechanical behaviour of CaCO3 in polyethylenes
Automotive engineering | 2012
|The investigation of mechanical behavior of calcium carbonate in polyethylenes
Automotive engineering | 2013
|Mechanical Basis for Pattern Analysis
SAE Technical Papers | 1970
|