(Key words : polyethylene, slow crack growth, primary structural parameter)
In this paper molecular weight and SCB data obtained experimentally or digitally
generated are combined into a single, primary structural parameter (PSP2) and used to
rapidly screen the slow crack growth resistance of a variety of polyethylene resins. Our
results show that PSP2 values obtained for resins made using different catalysts (both
dual and single catalyst systems) and hence, different polymer architectures, correlate
well with results obtained from several short-term tests (i.e., Tensile % NDR, PENT, SPNCTL, ESCR) as well as pipe hoop stress data. Furthermore, due to recent
advancements in modeling the effects of structure on density, PSP2 values can now be
generated for any digital MWD and SCB distributions (what if scenarios). The predictive
ability PSP2 values and the use of this parameter to unravel structural affects on SCG
in order to better design high performance pipe resins will be presented and discussed.
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Author(s) : Paul J. Freudenthaler, Joerg Fischer, Mathias Eder, Reinhold W. Lang
For controlled water disinfection, typically chlorine is used and preliminary studies
demonstrate its aging and crack growth acceleration effects on polyolefin pipe materials
[1, 2]. Although the use of recycled plastics is not prohibited in some ISO standards for
polyolefin piping systems [3–5], only small amounts...
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Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang, Susan C. Mantell
This research addresses the effect of nucleation on the global aging behavior and the fatigue crack growth (FCG) resistance of commercial alpha- and beta-nucleated polypropylene random copolymer pipe grades (PP-R) when exposed to chlorinated water (5 mg/l free chlorine) at an elevated temperature of 60°C. Comparing...
Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang
Cyclic tests with cracked round bar (CRB) specimens have been used for some time to characterize the slow crack growth behavior of polyolefin pipe grade materials. In fact, most recently a standardized test procedure for cyclic CRB testing has been released in ISO 18489. To obtain kinetic data for cyclic crack growth...
Author(s) : Paul van Doesburg, Berend Stel, Rob Spekreijse
PVC-O is the accepted pipe solution for the future. Worldwide, more and more countries go in the direction of PVC-O. The main applications for PVC-O at this moment are potable water, wastewater, irrigation and gas.
PVC-O is produced for many years from the 80’s until 2007 the sizes were in majority small (mainly...
Author(s) : Mark J. Lamborn, Pam L. Maeger, Rick E. Kunc, Vivek Rohatgi, Paul J. DesLauriers, Ashish M. Sukhadia
Dual cooling is a post-extrusion cool down process employed for polyethylene (PE) pipe, whereby either water or ambient air is forced through the pipe bore following extrusion, in order to accelerate cooling. The primary benefits offered by the dual cooling process are increased production rates and reduced resin...