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Ageing properties of polyamide-12 pipes exposed to fuels with and without ethanol
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2008 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 93, no 10, 1846-1854 p.Article in journal (Refereed) Published
Abstract [en]

The chemical and physical properties of polyamide-12 (PA12) fuel pipes/lines, aged for <= 2400 h at 110 degrees C, have been investigated. The pipes, containing fuel with or without ethanol, were either of a single PA12 layer, or of two PA12 layers surrounding a poly(vinylidene fluoride) barrier layer. The molar mass of the inner surface region obtained by size-exclusion chromatography was reduced during ageing. and optical microscopy revealed a surface that was partly dissolved in the presence of ethanol. Infrared spectroscopy revealed a rapid loss of plasticiser, especially in the presence of ethanol, and the fuel contained plasticiser and other polymer related components. Immersion tests at 60 degrees C showed that the swelling of the pipe and the amount of dissolved material were greatest for the fuels with intermediate ethanol content (50 vol.%). Aged samples experienced an increase in melting point, presumably, to a large extent, due to the loss of plasticiser and/or PA12-related components. In addition, for several samples, the crystallinity seemed to increase with ageing. (C) 2008 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
2008. Vol. 93, no 10, 1846-1854 p.
Keyword [en]
URN: urn:nbn:se:kth:diva-12043DOI: 10.1016/j.polymdegradstab.2008.07.025ISI: 000260648800019ScopusID: 2-s2.0-52049113185OAI: diva2:300206
QC20100722Available from: 2010-02-25 Created: 2010-02-25 Last updated: 2010-07-22Bibliographically approved
In thesis
1. The Ageing of Fuel Lines Based on Polyamide-12
Open this publication in new window or tab >>The Ageing of Fuel Lines Based on Polyamide-12
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Today, the use of bio-fuels for cars is increasing. There is a wide range of biofuelsavailable world wide, in Sweden ethanol containing fuels are favoured.For car manufacturers there is a need to be able to predict short and long termproperties of fuel lines subjected to ethanol containing fuels to ensure properlong term behaviour. The presented method for ageing in “close to real”environment involved circulating fuel inside the tubes and air on the outside attwo temperatures, 50°C and 110°C. The exposure time was extensive in the50°C case, almost 3 years, and the ageing at 110°C was conducted for 100days. Polyamide-12 was chosen as pipe material, which is also used in realparts. Tensile testing was used to assess the mechanical changes caused byageing. Long ageing times and high ethanol levels resulted in low extensibility.In the case of fuel with 25 vol.% ethanol at 110°C (100 days) the samplesshowed no macroscopic yielding. Even at 50°C a time induced loss ofextensibility was observed (80 vol.% ethanol). However, at ethanol levels of 0and 22 vol.% the extensibility was not reduced even after the 3 years of ageing.The changes at short times were interpreted as being due to loss of plasticizer.The changes at long ageing times were thoroughly investigated. The change incrystallinity, pipe swelling, leaching and the decrease in extensibility were allgreatest in the pipes subjected to ethanol. As expected, the molar massdecreased as the ethanol level increased and a good correlation between molarmass and extensibility was observed. A method for determining the fuelpermeation properties was developed. Fuel lines were subjected to circulatingfuels in the same manner as in the ageing tests and the surrounding air wasanalysed for fuel components with a flame ionisation detector. Higher level ofethanol increased the individual fuel component fluxes as well as the total fluxand also the temperature effect on the flux was significant. Finally it should bementioned, that ethanol was not always an unwanted ingredient; adding a smallamount of ethanol to the ethanol-free fuel prevented premature pipe failure at110°C.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 71 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2010:6
pipes, ethanol
National Category
Other Materials Engineering
urn:nbn:se:kth:diva-12050 (URN)978-91-7415-552-5 (ISBN)
Public defence
2010-03-19, F3, KTH, Stockholm, 10:00 (Swedish)
QC20100722Available from: 2010-02-26 Created: 2010-02-26 Last updated: 2010-07-22Bibliographically approved

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