Autoxidation of semicrystalline polyethylene

Winslow, F. H.; Hellman, M. Y.; Matreyek, W.; Stills, S. M.

doi:10.1002/pen.760060317

Cited by 64 publications

(26 citation statements)

References 6 publications

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“…Hence, a small degree of oxidation in the amorphous regions can dramatically change the polymer properties (Scheirs 2000). Winslow et al (1966) observed that oxidation in the amorphous region can lead to crystallinity increase in these regions due to scission of constrained chains in the amorphous material allowing the resulting freed segments to crystallise. In addition, Luongo (1963) showed an increase in crystallinity of linear and branched polyethylene followed the increase in the oxidation due to the replacement of C-H bonds by C-O bonds in the amorphous phase.…”

Section: Changes In the Polymer Morphology Due To Chemical Degradatiomentioning

confidence: 99%

“…Although the notch (20% of the thickness in depth) in the SCR test tends to mitigate the effect of degradation from one surface, the degradation of the opposite surface of the GMB to the notch may decrease the resistance of the ligament behind the notch and facilitate the propagation of the crack from the root of the notch in the ligament and, if so, decrease the SCR when there is sufficient surface degradation. On the other hand, Winslow et al (1966) indicated that reduction in tensile strength of polyethylene due to slight oxidation could be also restored by melting and remoulding the specimen as melting of the broken chains due to localised degradation could be redistributed throughout the polymer mass. Thus, by analogy, a complete melt for 6 min in the MI test could average the effect of localised degradation throughout the thickness of the polymer and thus the MI test is expected to be less sensitive to early surface or near surface degradation than SCR.…”

Section: Surface Degradation and Scrmentioning

confidence: 99%

“…an increase in the crystallinity) in a phenomenon known as 'chemi-crystallisation'. The term, chemi-crystallisation, refers to 'chemically-induced crystallisation as a process that is distinguishable from thermal annealing' (Winslow et al 1966). Holmström (1979) showed that an effect of chemi-crystallisation evident from DSC thermograms was the formation of a more well-ordered crystalline region with a higher peak melting temperature for linear polyethylene heated at 105°C.…”

Section: Changes In the Polymer Morphology Due To Chemical Degradatiomentioning

confidence: 99%

“…chemi-crystallisation) in addition to the effect of annealing (and thus an increase melting temperature of the crystals due to thickening) when continuously exposed to 115°C for 8.9 months. This emphasises the role of oxygen availability and the subsequent oxidative degradation in the polymer as suggested by many investigators (Luongo 1963;Winslow et al 1966;Holmström 1979;Dörner and Lang 1998b;Scheirs 2000) in affecting the polymer morphology. At this time the GMB exhibited a very brittle behaviour as was evident from the total loss of SCR and a similar behaviour to that described by Müller and Jacob (2003) when they characterised brittleness of HDPE GMBs as a situation where 'bending the GMB specimen by hand, one can easily break it without yielding in the fracture surface'.…”

Section: Gmb Physical Properties At Elevated Temperatures During Air mentioning

confidence: 99%

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Effect of high temperatures on the physical and mechanical properties of HDPE geomembranes in air

Abdelaal

Rowe

Hsuan

et al. 2015

Geosynthetics International

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The effect of elevated temperatures, particularly between 95 and 115°C as encountered in some geoenvironmental applications, on the physical and mechanical properties of high-density polyethylene (HDPE) geomembranes (GMBs) is examined. Four commercially available HDPE GMBs were incubated in air at temperatures ≥ 85°C. Investigation of the thermograms by differential scanning calorimetry showed a significant change in the polymer morphology with an increase of the incubation temperature and duration, especially at 105 and 115°C. The morphological changes due to annealing involve thickening of the lamella crystals of the polymer and a change in the tie molecules joining the lamella crystals. The effect of annealing was most evident in the stress crack resistance of the GMB incubated at 105 and 115°C prior to polymer degradation. In particular, an increase in stress crack resistance due to annealing could mask the effects of polymer degradation at temperatures above 95°C. Changes in morphology did not affect melt index whose changes were largely attributed to polymer degradation.

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Section: Changes In the Polymer Morphology Due To Chemical Degradatiomentioning

confidence: 99%

Section: Surface Degradation and Scrmentioning

confidence: 99%

Section: Changes In the Polymer Morphology Due To Chemical Degradatiomentioning

confidence: 99%

Section: Gmb Physical Properties At Elevated Temperatures During Air mentioning

confidence: 99%

See 2 more Smart Citations

Effect of high temperatures on the physical and mechanical properties of HDPE geomembranes in air

Abdelaal

Rowe

Hsuan

et al. 2015

Geosynthetics International

View full text Add to dashboard Cite

show abstract

“…The degradation could be due to (i) chemical degradation of the polyethylene that involves oxidative degradation either by UV radiation (photo-oxidation) or thermal oxidation (Winslow et al 1966;Haxo and Nelson 1984;Haxo and Haxo 1989;Koerner et al 1990), which are considered to be the most harmful for HDPE GMBs exposed to the elements (e.g., Hsuan et al 1991;Rowe et al 2003), and (or) (ii) by a change in morphological structure of the GMB (Ewais and Rowe 2014b) that may result in increasing the GMB crystallinity (known as physical ageing of the GMB) as the polymer tends to be more glassy and less rubbery (Kovacs 1958;Struik 1977;Kubát et al 1989) and (or) decreasing the stress crack resistance of the GMB (Ewais and Rowe 2014b).…”

Section: Introductionmentioning

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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Effect of fabrication method and resin type on performance of tibial bearings

Currier

Collier

et al. 2000

J. Biomed. Mater. Res.

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Polyethylene has been used successfully for more than 30 years as an orthopedic bearing material. During this time, several polyethylene resins and fabrication methods have been used to produce bearings. Some bearings fail prematurely due to fatigue, which has been linked to oxidation and degradation of mechanical properties resulting from gamma sterilization in air. Fabrication method and/or resin have been hypothesized to govern whether oxidative degradation occurs in gamma-sterilized bearings. This study evaluates the effect of fabrication (machining/direct compression molding) and resin type on oxidation and the resulting mechanical properties for a large series of never-implanted bearings. While many molded bearings studied exhibit lower oxidation than machined bearings, fabrication method is not a significant predictor of oxidation. Resin type and shelf-age are found to be significant predictors of oxidation. Bearings fabricated from Himont 1900 exhibit lower oxidation than those from GUR 415/412 at comparable times after gamma in air. However, Himont 1900 bearings lose strength and elongation at lower oxidation levels than GUR 415/412 bearings. But since Himont 1900 oxidizes more slowly, Himont 1900 bearings retain mechanical properties for longer shelf times than comparable GUR 415/412 bearings. These effects are seen in retrievals as well.

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Autoxidation of semicrystalline polyethylene

Cited by 64 publications

References 6 publications

Effect of high temperatures on the physical and mechanical properties of HDPE geomembranes in air

Effect of high temperatures on the physical and mechanical properties of HDPE geomembranes in air

Ageing of exposed geomembranes at locations with different climatological conditions

Effect of fabrication method and resin type on performance of tibial bearings

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