FTIR and X-Ray photoelectron spectral (XPS) evidence for interaction between natural ester and cellulose paper

Several researchers have claimed that Natural Esters enhance the thermal stability of insulation paper. It has been claimed that the chemical interaction accounts for slowing down of ageing of paper and enhancement of insulation life. The enhancement of paper life translates to transformer asset life enhancement. We have conducted aging studies at 120 °C on normal Kraft paper (NKP) as well as thermally upgraded Kraft paper (TUK). The results showed unambiguous development of carbonyl structure on the paper surface - both normal Kraft paper and thermally upgraded paper. These results are further corroborated with X-ray photoelectron spectroscopy (XPS) which lends further support to the formation of carbonyl structure on the paper surface. The results are interpreted in terms of transesterification reaction taking place between cellulosic hydroxyls and the carboxylate of oil. It is suggested that this interaction leads to development of hydrophobicity on the cellulose paper surface which reduces moisture uptake by paper.