Antioxidant depletion patterns of high-density polyethylene geomembranes in landfills under different exposure conditions

2021 ◽  
Vol 121 ◽  
pp. 365-372
Author(s):  
Weishi Li ◽  
Ya Xu ◽  
Qifei Huang ◽  
Yuqiang Liu ◽  
Jingcai Liu
Keyword(s):  
High Density Polyethylene ◽  
High Density ◽  
Exposure Conditions

Ageing of exposed geomembranes at locations with different climatological conditions

2015 ◽  
Vol 52 (3) ◽  
pp. 326-343 ◽  
Author(s):  
R. Kerry Rowe ◽  
A.M.R. Ewais
Keyword(s):  
High Pressure ◽  
Crack Resistance ◽  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Cold Climate ◽  
Field Conditions ◽  
Research Site ◽  
Hot Climate ◽  
Exposure Conditions

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.

Effects of exposure conditions on the depletion of antioxidants from high-density polyethylene (HDPE) geomembranes

2002 ◽  
Vol 39 (6) ◽  
pp. 1221-1230 ◽  
Author(s):  
Henri P Sangam ◽  
R Kerry Rowe
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Accelerated Ageing ◽  
Time Intervals ◽  
Msw Landfill ◽  
Exposure Conditions

Laboratory-accelerated ageing tests have been conducted to examine the depletion of antioxidants from high-density polyethylene (HDPE) geomembranes as a result of their exposure to various environments. Samples of 2.0 mm thick geomembrane were exposed to air, water, and municipal solid waste (MSW) leachate at temperatures of 22, 40, 55, 70, and 85°C. At various time intervals, samples were collected and the oxidative induction time (OIT) was evaluated. The results indicated that the antioxidants are depleted at rates 1.6 to 2.4 times faster for samples in water than for air-exposed samples. For samples in leachate, the depletion is about 4 times faster than that in air and 1.6–3.2 times faster than that in water. Using these rates, it is estimated that if the geomembrane examined were used as an MSW landfill primary liner, it would take at least 40 years to deplete the antioxidants from the geomembrane at a temperature of 33°C and over 150 years at a temperature of 13°C.Key words: ageing, antioxidants, durability, oxidative induction time, HDPE geomembrane, antioxidant depletion time.

Composition and Surface Topography Effects on Apatite-Forming Ability of Ceramic-Polymer Composites

2003 ◽  
Vol 774 ◽  
Author(s):  
Susan M. Rea ◽  
Serena M. Best ◽  
William Bonfield
Keyword(s):  
Surface Topography ◽  
High Density Polyethylene ◽  
High Density ◽  
Apatite Layer ◽  
Biologically Active ◽  
Human Blood Plasma ◽  
Apatite Formation ◽  
Polyethylene Matrix ◽  
Composite Surface ◽  
X Ray

AbstractHAPEXTM (40 vol% hydroxyapatite in a high-density polyethylene matrix) and AWPEX (40 vol% apatite-wollastonite glass ceramic in a high density polyethylene matrix) are composites designed to provide bioactivity and to match the mechanical properties of human cortical bone. HAPEXTM has had clinical success in middle ear and orbital implants, and there is great potential for further orthopaedic applications of these materials. However, more detailed in vitro investigations must be performed to better understand the biological interactions of the composites and so the bioactivity of each material was assessed in this study. Specifically, the effects of controlled surface topography and ceramic filler composition on apatite layer formation in acellular simulated body fluid (SBF) with ion concentration similar to those of human blood plasma were examined. Samples were prepared as 1 cm × 1 cm × 1 mm tiles with polished, roughened, or parallel-grooved surface finishes, and were incubated in 20 ml of SBF at 36.5 °C for 1, 3, 7, or 14 days. The formation of a biologically active apatite layer on the composite surface after immersion was demonstrated by thin-film x-ray diffraction (TF-XRD), environmental scanning electron microscopy (ESEM) imaging and energy dispersive x-ray (EDX) analysis. Variations in sample weight and solution pH over the period of incubation were also recorded. Significant differences were found between the two materials tested, with greater bioactivity in AWPEX than HAPEXTM overall. Results also indicate that within each material the surface topography is highly important, with rougher samples correlated to earlier apatite formation.

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