Degradation of cellulosic insulation in power transformers: a SEC–MALLS study of artificially aged transformer papers

The molecular weight distributions of artificially aged transformer papers were studied using SEC–MALLS with 0.5 % DMAc/LiCl as solvent, providing chain length distributions and averages. The slow dissolution and presence of non-cellulosic contaminants tend in some cases to introduce errors in the D...

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Bibliographic Details
Published in:Cellulose (London) 2013-08, Vol.20 (4), p.2003-2011
Main Authors: Kes, Mürşide, Christensen, Bjørn E.
Format: Article
Language:English
Subjects:
Bioorganic Chemistry
Ceramics
Chemistry
Chemistry and Materials Science
Composites
Contaminants
Data processing
Degradation
Glass
Insulation
Lithium chloride
Molecular weight
Natural Materials
Organic Chemistry
Original Paper
Physical Chemistry
Polydispersity
Polymer Sciences
Sustainable Development
Transformers
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Summary:The molecular weight distributions of artificially aged transformer papers were studied using SEC–MALLS with 0.5 % DMAc/LiCl as solvent, providing chain length distributions and averages. The slow dissolution and presence of non-cellulosic contaminants tend in some cases to introduce errors in the DP w estimates, and a modified data processing procedure was developed to correct for extraneous scattering. Data were compared to the intrinsic viscosities obtained in 0.5 M Cuen and the ‘viscosimetric DP’ calculated thereof according to ISO 5351. DP visc was 2–3 times lower than the weight average DP (DP w ), but closer to or slightly above the number average DP (DP n ) obtained by SEC–MALLS in the case of pure cellulose. Ageing of transformer papers were in some cases associated with changes in the polydispersity (DP w /DP n ). The apparent degradation rate (defined as δ(1/DP)/δt) gradually decreased with time, resulting in a tendency for a ‘level-off’ DP in the range 200–300 for DP visc and DP n , and roughly 1,000 for DP w .
ISSN:0969-0239
1572-882X
DOI:10.1007/s10570-013-9963-x