Degradation assisted crack growth of polyethylene exposed to chlorine dioxide water solution
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Tape samples of medium density polyethylene withthickness of 0.4 mm were supplied containing 0.1% and 0.3 % of four differentphenolic stabilizers. These samples exposed continuously and interrupted (6hour/day) to 10 ppm chlorine dioxide water solution with PH: 6.8 at 70˚C. The antioxidants life times were followed bydifferential scanning calorimetry through oxidation induction time. Sample with0.3% antioxidants exhibit an unstable and longer OIT results in the interruptedexposure system in comparison to o.3% samples in continues system. Solubilitydifficulties and precipitation of antioxidants with 0.3% concentration inpolyethylene matrix supposed to be reason for this non reliable data. Sampleswith 0.1% antioxidants approximately followed the same OIT profile as afunction of exposure time in both continues and interrupted system. Surface degradationsof tapes (with 0.1% stabilizer) were examined by IR spectroscopy and carbonylbond formation on sample after depletion time of stabilizers confirmed for allsamples. Carbonyl index rate corresponding to chemical degradation of samplesdepends on the antioxidant type even after depletion time (OIT: 0.0) ofantioxidants. Micrographs of exposed sample after necking were used tocalculation of chemical assisted crack growth as function of exposure time. Theonset for crack initiation times for matrix polymer and disintegration ofdegraded surface from fresh polymer occurs in longer time than depletion timeof antioxidants. It depends on antioxidants type in which the crack growth ratefor studied antioxidants including Irganox 1330 and Irganox 3114 were 5 µm and3.5 µm per 1000 min exposure time after crack initiation onset.
Place, publisher, year, edition, pages
2012. , 27 p.
Polyethylene, chlorine dioxide, antioxidant depletion, micrograph, crack growth
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-150825OAI: oai:DiVA.org:kth-150825DiVA: diva2:745566