Degradation behaviour of HDPE geomembranes with high and low initial high-pressure oxidative induction time

Ewais, A.M.R.; Rowe, R. Kerry; Scheirs, John

doi:10.1016/j.geotexmem.2014.01.004

Cited by 45 publications

(19 citation statements)

References 48 publications

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“…For the 0.5 mm GMB, the Std-OIT was the same as that for the other thicknesses but there was a slight different in the HP-OIT that may arise from it being was manufactured in a different production run or from variability during manufacturing or testing; however the difference was not statistically significant (at the 95% confidence level, for five test replicates). Ewais et al (2014) investigated the ageing of the 1.5 mm GMB (Table 1) …”

Section: Oit Tests Resultsmentioning

confidence: 99%

“…Std-OIT and HP-OIT tests widely used to monitor the depletion of antioxidants/stabilisers in HDPE GMBs with ageing (Thomas and Ancelet 1993;Hsuan and Koerner 1998;Müller and Jacob 2003;Li and Hsuan 2004;Rowe et al 2008Rowe et al , 2009Rowe et al , 2010Ewais et al 2014). Standard oxidative induction time (Std-OIT; ASTM D3895) and high pressure oxidative induction time (HP-OIT; ASTM D5885) tests were conducted using TA Instruments, Q-100 series differential scanning calorimeter (DSC) and Q20 series DSC, respectively.…”

Section: Oxidative Induction Time (Oit) Testmentioning

confidence: 99%

“…The high HP-OIT values (. 900 min), combined with the results of a trace nitrogen analysis, indicate the presence of light stabilisers that contain nitrogen in their chemical structure and suggest the presence of hindered amine light stabiliser in the GMBs(Thomas and Ancelet 1993;Hsuan and Guan 1997;Kohler and Kröhnke 1999;Scheirs 2009;Ewais et al 2014).…”

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confidence: 96%

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Effects of blown film process on initial properties of HPDE geomembranes of different thicknesses

Ewais¹,

Rowe²

2014

Geosynthetics International

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The differences in the properties of five high density polyethylene geomembranes (GMBs) of different thicknesses made by the same manufacturer from same GMB resin are investigated. The 1.0, 1.5, 2.0 and 2.4 mm thick GMBs investigated were manufactured during the same production run by changing the pulling speed of the GMB out of the extrusion die, such that, the pulling speed decreased with increasing thickness. There were no differences in the initial HP-OIT or Std-OIT values of the different GMBs. However, there were differences in the key mechanical and physical properties of the GMBs that cannot be simply explained by the increase in the amount of material due to increasing GMB thickness. These differences are explained by differences in the morphological structure of the GMBs arising from the different thermal and stress histories experienced during the manufacturing process. The effects of the differences in the morphological structure are discussed in terms of: the decrease in the relative differences between the stress-elongation curves in the machine and cross-machine directions as thickness increases; changes in the enthalpies of melting and crystallisation by differential scanning calorimetry with changing thickness; and the different stress crack resistance (SCR) for the GMBs. For example, thinner GMBs had a greater difference between the SCR in the machine and cross-machine direction. Increasing the GMB thickness from 1.5 to 2.4 mm resulted in increasing the SCR from , 800 to , 1100 h in the cross-machine direction and decreasing its SCR from , 4100 to , 2000 h in the machine direction. Thus, GMBs of different thickness manufactured from the same resin can be expected to have differences in their physical and mechanical properties that are dependent on the additional material but also the difference in the tension and cooling rate experienced during the manufacturing process.

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Section: Oit Tests Resultsmentioning

confidence: 99%

Section: Oxidative Induction Time (Oit) Testmentioning

confidence: 99%

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Effects of blown film process on initial properties of HPDE geomembranes of different thicknesses

Ewais¹,

Rowe²

2014

Geosynthetics International

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“…Both standard (Std) and high pressure (HP) oxidative induction time (OIT) tests were performed in accordance with ASTM 2007 standard D3895 and ASTM 2012c standard D5885, respectively, to infer the relative concentration of antioxidants in GMBs (Pauquet et al 1993;Thomas and Ancelet 1993;Hsuan and Guan 1997;Hsuan and Koerner 1998;Sangam and Rowe 2002;Müller and Jacob 2003;Gulec et al 2004;Li and Hsuan 2004;Rowe et al 2008Rowe et al , 2009Rowe et al , 2010Ewais et al 2014). Std-OIT tests were conducted at 200°C and 35 kPa oxygen pressure using a differential scanning calorimeter (DSC, TA Instruments Q-100); whereas, HP-OIT tests were conducted at 150°C and 3450 kPa oxygen pressure using a TA Instruments Q20 DSC to detect antioxidants-stabilizers (e.g., hindered amine light stabilizers (HALS)) that are not effective at the 200°C condition (Thomas and Ancelet 1993;Fay and King 1994) of the Std-OIT test.…”

Section: Oxidative Induction Time (Oit) Testmentioning

confidence: 99%

“…(1)), the HP-OIT depletion rate over the first 6 years would be 0.00314 month −1 . It is difficult to infer the residual value of the HP-OIT that will eventually be measured due to climatic exposure because it is not known whether the antioxidants-stabilizers detected by HP-OIT would experience synergistic or antagonistic mechanisms during ageing as discussed by Ewais et al (2014); however, the HP-OIT of this GMB depleted to less than 400 min in leachate exposure and the typical residual HP-OIT value in the literature for GMBs is around 70 to 100 min (e.g., Rowe et al 2010;Ewais et al 2014). Thus, if one assumes that the GMB has a residual HP-OIT value between 100 and 400 min; and that HP-OIT depletion would follow the exponential decay model (eq.…”

Section: Oit Depletionmentioning

confidence: 99%

Ageing of exposed geomembranes at locations with different climatological conditions

Rowe

2015

Can. Geotech. J.

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Abstract:The degradation of high-density polyethylene (HDPE) geomembranes exposed to the elements depends, inter alia, on the climatological conditions. This study investigates the degradation in the properties of HDPE geomembranes installed at two mine facilities after almost 16 years of exposure in a warm-hot climate and at a research site after 6 years of exposure in a mild-cold climate. Samples were exhumed at the field sites from different locations and the properties of the geomembrane were measured in the laboratory. The depletion of antioxidants detected by the standard oxidative induction time (Std-OIT) test for the geomembrane installed at the research site was faster on the slope than on the base; however, there was negligible difference in the depletion of antioxidants-stabilizers detected by the high-pressure oxidative induction time (HP-OIT) test between the slope and base. Under the field conditions described, the antioxidant depletion time for the exposed geomembrane installed at the research site (mild-cold climate) was inferred to be 20 to 54 years. The exposed HDPE geomembranes installed at the mine facilities (warm-hot climate) have reached the time of nominal failure based on their stress crack resistance. However, they have not ruptured under the exposure conditions even though the stress crack resistance has dropped to as low as 70 h at some locations.Key words: geosynthetics, field case, exposed geomembranes, high-density polyethylene (HDPE), ultraviolet (UV) index, geomembrane degradation.Résumé : La dégradation des géomembranes en polyéthylène à haute densité (PEHD) exposées aux éléments dépend entre autres des conditions climatiques. Cette étude évalue la dégradation des propriétés de géomembranes en PEHD installées sur deux sites miniers après 16 ans d'exposition dans un climat chaud et sur un site de recherche 6 ans après l'exposition dans un climat tempéré-froid. Des échantillons ont été exhumés des sites sur le terrain à plusieurs endroits et les propriétés de la géomembrane ont été mesurées en laboratoire. L'épuisement en antioxydants, détecté à l'aide de l'essai du temps d'induction de l'oxydation standard (Std-OIT), de la géomembrane installée au site de recherche était plus rapide sur la pente que sur la base, cependant il y avait une différence négligeable entre l'épuisement des antioxydants-stabilisateurs détectés par l'essai du temps d'induction de l'oxydation à haute pression (HP-OIT) sur la pente et sur la base. Dans les conditions de terrain décrites, le temps d'épuisement des antioxydants pour la géomembrane exposée installée au site de recherche (climat tempéré-froid) a été estimé à 20 à 54 ans. Les géomembranes en PEHD exposées installées sur les sites miniers (climat chaud) ont atteint leur temps nominal de rupture basé sur leur résistance aux fissures de contrainte. Cependant, elles n'ont pas cédé sous les conditions d'exposition même si la résistance aux fissures de contrainte a diminué jusqu'à 70 h à certains endroits. [Traduit par la Rédaction] Mots-clés : géosynt...

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Improving thermo‐oxidative degradation resistance of bamboo fiber reinforced polypropylene composite with antioxidants. Part I: Screening of antioxidants

Ren

Zhang

Wang

et al. 2016

J of Applied Polymer Sci

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In this study, the effect of antioxidant application (applied in different combinations, ratios and contents) on the thermo‐oxidative degradation resistance of bamboo fiber polypropylene composites (BFPCs) were investigated, with oxidative induction time (OIT), weight loss, surface color, and flexural mechanical properties as the main indicators for evaluation. The results showed the addition of antioxidants could greatly increase the OIT and reduce the weight loss and color change of the composites after 900 h of thermal weathering. Meanwhile, the flexural mechanical properties were little affected or even slightly improved. The combination of 1076 and DLTP antioxidants at a ratio of 2:1 and 0.2 wt % content was found to exhibit the best thermal oxidation resistance with respect to the OIT, mechanical properties and cost. Our study indicate that the OIT can serve as a simple and quick indicator for the evaluation of thermo‐oxidative resistance of BFPC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44198.

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Degradation behaviour of HDPE geomembranes with high and low initial high-pressure oxidative induction time

Cited by 45 publications

References 48 publications

Effects of blown film process on initial properties of HPDE geomembranes of different thicknesses

Effects of blown film process on initial properties of HPDE geomembranes of different thicknesses

Ageing of exposed geomembranes at locations with different climatological conditions

Improving thermo‐oxidative degradation resistance of bamboo fiber reinforced polypropylene composite with antioxidants. Part I: Screening of antioxidants

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