Depletion of antioxidants and polymer degradation in polyethylene pipes distributing chlorinated water
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Antioxidantförbrukning och polymernedbrytning i polyetenrör för distribution av klorerat vatten (Swedish)
Tap water disinfected by chlorine dioxide is oxidizing polymers and influences the properties of distributing pipes that usually made in polyethylene. Though it kills bacteria in drinking water, chlorine dioxide and its byproducts potentially shorten the polyethylene pipes service time.
Squalane, which is a liquid hydrocarbon, is used in the squalane test. The chlorinated water and squalane forms dual-phase which makes easier for sampling from the squalane phase. The samples for tape test were pressed by Fontune press and were suspended in ClO2 water. In both tests ClO2 water was changed every 30 min to keep the concentration of chlorine constant.
The oxidation induction time (OIT), which proportional to the concentration of the antioxidants, was used to analyze the depletion time of the antioxidants. Increasing chlorinated water bath temperature did not increase the degradation rate of the antioxidants in squalane test. However the OIT results from tape test showed a temperature-dependence manner.
Tensile test on the materials that exposed to chlorinated water at concentration of 10 ppm of chlorine dioxide until depletion of antioxidants showed the depletion of antioxidants did not significantly affect the mechanical properties of the host material. There was a small decrease in tensile strain at break and tensile strain at tensile strength.
Scanning electron microscopy (SEM) images showed there were micro-cracks formed on the surface of solid specimen after exposed to water containing chlorine dioxide and tensile test. However, the same sample without expose
Place, publisher, year, edition, pages
2011. , 41 p.
Polyolefin, antioxidants, Chlorine dioxide water media, OIT (Oxygen induction time), degradation.
IdentifiersURN: urn:nbn:se:kth:diva-41504OAI: oai:DiVA.org:kth-41504DiVA: diva2:444286
Subject / course
Degree of Master - Materials and Sensors System for Environmental Technologies
UppsokPhysics, Chemistry, Mathematics