Pilz, Lang
Posters - Additional Information # 2001 Munich
To characterize the viscoelastic properties such as creep modulus and time dependent Poissons’s ratio of commercial medium and high density polyethylene materials (PE-MD, PE-HD), in total 5 types of polyethylene (PE) (pipe grades and non-pipe grades) with densities ranging from 0.928 to 0.951 g/cm3 were investigated. The development and implementation of a suitable test methodology including dynamic mechanical analysis and short-term creep tests combined with proper polymer physics and mechanics concepts allowed for a description of the viscoelastic behaviour of these PE materials over an extended time scale from 10-2 s to 50 years. In good agreement with the results of tests additionally performed on pipe specimens, creep modulus values were found to decrease up to 1.5 orders of magnitude over the time scale indicated. As expected, creep modulus data were found to be strongly affected by the material density. In addition, values for Poisson´s ratio were found to increase with time with short-term values of around 0.4 and extrapolated values approaching 0.5 at 50 years.
Related papers
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...
Author(s) : Markus Gall, Reinhold W. Lang, Joerg Fischer, Ansgar Niehoff, Steven Schmidt
Despite recent efforts in promoting the utilization of recycled polymeric materials for more diverse and more advanced applications, there are still significant knowledge gaps with regards to the applicability of certain recyclate types for specific “re-use” purposes. When it comes to pipe applications, for instance,...
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, Patrick R. Bradler, Reinhold W. Lang
In the present paper, a novel test system for conducting fatigue crack growth (FCG) experiments under superimposed mechanical-environmental conditions is presented. FCG experiments were performed on a polypropylene (PP) grade and a short-glass fiber reinforced polyamide 66 (PA-GF) grade as model materials. The...
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) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang, Gernot M. Wallner
The present paper aims to study the crack growth resistance of a black-pigmented polypropylene pipe grade when exposed to elevated temperatures and various environmental media (air, deionized water, ionized water with a specific chloride content, and chlorinated water) under the simultaneous application of cyclic...
Author(s) : Reinhold W. Lang, Patrick R. Bradler, Joerg Fischer, Dominik Poehlmann, Steven Schmidt, Ansgar Niehoff
In the present paper, a highly effective test and characterization concept for polymer recyclate materials is proposed and validated. Based on the proposed methods, a study was carried out to investigate the potential of in-plant and post-use PE recyclates from various applications to be utilized in PE recyclate...
Author(s) : P. F. Schoeffl, R.W. Lang
To accommodate the recent industrial interests to utilize PE-HD pipes for oil field applications (e.g. injection water pipes, flow lines), this paper introduces a “fully integrated test concept” to allow a comprehensive pipe lifetime prediction under severe environmental conditions. Moreover, experimental set-ups and...
Author(s) : Anna M. Hartl, A. Buryak and R.W. Lang
The ductile behaviour of PE in Region I of the pipe failure regime is mainly governed by the time/ and temperature-dependent yield stress of the polymer [1]. Two different deformation mechanisms are relevant in PE. One governing shorter times and/or lower temperatures and the other longer times and/or higher...
Author(s) : Lang, Frank, Pinter
For lifetime prediction of pressurized polyethylene (PE) pipes based on methods of the linear elastic fracture mechanics the knowledge of the crack resistance and kinetics of creep crack growth (CCG) is essential. In the present work a rather brittle non pipe material was used to develop a methodology for an...
Author(s) : Lang, Pinter, Balika, Haager
The current discussion and future situation in the field of polyethylene (PE) pressure pipes for water and gas supply may be characterized by the following aspects and topics. Continuous developments by polymer suppliers in the last decades have resulted in improved PE material grades, which in turn led to a...
Author(s) : Haager, Pinter, Lang
It is well known that resistance against slow crack growth is important for the lifetime of pressurized polyethylene (PE) pipes. Thus several methods have been proposed to evaluate the long-term performance of PE using fracture mechanics. It is generally believed that this leads to results more quickly compared to...
Author(s) : Pinter, Haager, Balika, Lang
In this work fatigue crack growth (FCG) experiments were used to evaluate the long term performance of polyethylene (PE) pipe grades. The FCG-tests were performed under a sinusoidal load at a frequency of 5 Hz, an R-ratio (Fmin/Fmax) of 0.1 and a test temperature of 23 °C. Eight different commercial pipe grades (PE 80...
Author(s) : Lang, Pinter, Stern
Engineering polymers, in particular special grades of poly(ethylene) (PE), are gaining importance in many pipe applications with targeted service lives of several decades. To ensure proper performance of such pipes over the required lifetime, polymer physics and mechanics concepts are needed which adequately account...
Author(s) : Balika, Lang
The creep crack growth (CCG) and the fatigue crack growth (FCG) behaviour of a commercial pipe grade PVC material was studied based on a linear elastic fracture mechanics (LEFM) methodology. The FCG tests were performed under sinusoidal load control at a frequency of 5 Hz and at R-ratios (Fmin/Fmax) of 0.1, 0.3 and...
Author(s) : Neumayer, Knauder, Pilz, Lang, Major
The importance of plastics piping systems based on glass fibre reinforced unsaturated polyester resins (GRP-UP) for water supply, industrial or sewer pipe works has continuously increased worldwide. Centrifugal casting (CC) is one of the most important technologies to manufacture CC-GRP-UP pipes. UP-resins, mineral...
Author(s) : Pinter, Lang
In this work the influence of three different stabiliser systems on the stress rupture behaviour of high density polyethylene (PE-HD) pipes under constant internal pressure was examined at 60 and 80 °C with special consideration of the quasi-brittle failure by growth of a single crack in the failure regime preceding...
Author(s) : Pinter, Lang
In this work differently stabilized Poly(ethylene) (PE)-types were characterized by linearelastic fracture mechanics (LEFM ) (creep crack growth tests) and internal pressure testing. In total, 6 PE formulations (2 polymer types with 3 stabilizer systems) were investigated. While no influence of stabilizer type was...
Author(s) : R.Lang
Members of the Association
