Chemical, physical and electrical properties of aged dodecylbenzene 2: thermal ageing of single isomers in air


Hosier, Ian L., Vaughan, Alun S., Sutton, Simon and Davis, Fred J. (2008) Chemical, physical and electrical properties of aged dodecylbenzene 2: thermal ageing of single isomers in air. IEEE Transactions on Dielectrics and Electrical Insulation, 15, (5), 1393-1405. (doi:10.1109/TDEI.2008.4656249).

Download

[img] PDF
Restricted to Registered users only

Download (957Kb) | Request a copy

Description/Abstract

The linear isomer of dodecylbenzene (DDB), 1-phenyldodecane, was aged at temperatures of 105 and 135 oC in air and the resultant products were analyzed using a range of analytical techniques. On ageing, the 1-phenyldodecane darkened, the acid number, dielectric loss and water content increased and significant oxidation peaks were detected in the infrared spectrum. When aged in the presence of copper, a characteristic peak at 680 nm was also detected by UV/visible spectroscopy but, compared with previous studies of a cable-grade DDB, the strength of this peak was much increased and no appreciable precipitate formation occurred. At the same time, very high values of dielectric loss were recorded. On ageing in the absence of copper, an unusually strong infrared carbonyl band was seen, which correlates well with the detection of dodecanophenone by gas chromatography / mass spectrometry and nuclear magnetic resonance spectroscopy. It was therefore concluded that the ageing process proceeds via the initial production of aromatic ketones, which may then be further oxidized to carboxylic acids. In the presence of copper, these oxidation products are present in lower quantities, most of these oxidation products being combined with the copper present in the oil to give copper carboxylates. The behavior is described in terms of a complex autoxidation mechanism, in which copper acts as both an oxidizing and a reducing agent, depending on its oxidation state and, in particular, promotes elimination via the oxidation of intermediate alkyl radical species to carbocations

Item Type: Article
ISSNs: 1070-9878 (print)
Divisions: Faculty of Physical Sciences and Engineering > Electronics and Computer Science > EEE
ePrint ID: 266833
Date Deposited: 27 Oct 2008 09:39
Last Modified: 27 Mar 2014 20:12
Further Information:Google Scholar
ISI Citation Count:1
URI: http://eprints.soton.ac.uk/id/eprint/266833

Actions (login required)

View Item View Item

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics