Oxidation geotextiles

Mueller WW et al. (2003) Comparison of the oxidative resistance of various polyolefin geotextiles. Geotextiles and Geomembranes 21 289-315 Muller WW (1996) Anfordemngen an die Schutzschicht fur die Dichtungsbahnen in der Kombinationsdichtung, Teil 2 Zulassungsanforderangen. Miill und Abfall 28 90-99... 

ENISO 13438 2004 Geotextiles and geotextile-related products - Screening Test Method for Determining the Resistance to Oxidation... 

EN ISO 13438 2004. Geotextiles and geotextile-related products — Screening test method for determining the resistance to oxidation. 

In situ soil conditions, primarily pH, are the governing factor related to the rate of chemical degradation of buried geotextiles. At extreme ranges of pH, oxidation and hydrolysis processes are influenced, which can compromise the integrity of the geotextile. 

It is well documented that polyolefins, which include polyethylene (PE) and polypropylene (PP), may degrade via reaction with oxygen. A geotextile s oxidation resistance depends strongly on the specific polymer, the stabilizer package, and the product s physical properties such as thickness and the surface area to mass ratio. 

Antioxidants are blended into the polymer resin during manufacturing to protect it from oxidation and are either compounds which trap free radicals and prevent reaction chain initiation or compounds which decompose hydro peroxides, therefore preventing them from forming free radicals and new reaction chains. Typically, a combination of both types of antioxidants is used in polyolefin geotextiles. 

Leaching of antioxidants from a geotextile may be modeled by immersion in water (or chemicals). In this context, pressurized air and oxygen have been used to accelerate the aging of geotextiles in autoclaves. The pressurized oxygen-rich environment employs a lower exposure temperature and serves to achieve observed oxidation in relatively short times. 

The effect of carbon black on thermal and photo-oxidative degradation of oriented PP geotextile tapes was studied by Horrocks et a/. The influence of particle size (16-60mn), stmcture, aggregate shape, specific surface volatile content and concentration was determined. Significant increases in thermal stabilities were observed when increasing carbon black content in PP composite. 

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