Acidic activation of cellulose and its esterification by long-chain fatty acid

Chauvelon, G.; Saulnier, Luc; Buléon, Alain; Thibault, Jean‐François; Gourson, C.; Benhaddou, R.; Granet, Robert; Krausz, Pierre

doi:10.1002/(sici)1097-4628(19991121)74:8<1933::aid-app7>3.0.co;2-k

Cited by 36 publications

(19 citation statements)

References 18 publications

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“…The acidity of natural ester is much higher than mineral oil, which can also contribute to the acid content of the pressboard immersed in natural ester. However, the higher acid content in pressboard immersed in natural ester is not bad thanks to the transesterification reaction [22,23,34,36]. Figure 7 shows that the acid content of the pressboard aged in mineral oil is very close to that aged in natural ester after aged for 93 days.…”

Section: Acids Content Of Oil Impregnatedmentioning

confidence: 89%

“…The high molecular acids produced by hydrolysis of natural ester can react with the cellulose via transesterification [22,23,34,36], as shown in equation (3). Under accelerated ageing, the reactive OH (hydroxyl) groups on the cellulose molecule become esterified with fatty acid in natural ester, which restrains the paper ageing [22,23,34,36].…”

Section: Acids Content Of Oilsmentioning

confidence: 99%

“…It is noteworthy that there is a decline (ageing for 93 days) in acid content of the pressboard in the ageing period. This is because a majority of carboxylic acids are easily dissolved in a moisture phase [36]. The acids may be transferred from pressboard to oil via moisture migration.…”

Section: Acids Content Of Oil Impregnatedmentioning

confidence: 99%

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A comparative study of physicochemical, dielectric and thermal properties of pressboard insulation impregnated with natural ester and mineral oil

Liao

Hao

Chen

et al. 2011

IEEE Trans. Dielect. Electr. Insul.

190

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Natural ester is considered to be a substitute of mineral oil in the future. To apply natural ester in large transformers safely, natural ester impregnated solid insulation should be proved to have comparable dielectric strength and thermal stability to mineral oil impregnated solid insulation. This paper mainly focuses on a comparative study of physicochemical, ac breakdown strength and thermal stability behavior of BIOTEMP natural ester/pressboard insulation and Karamay 25# naphthenic mineral oil/pressboard insulation after long term thermal ageing. The physicochemical and dielectric parameters including moisture, acids and the ac breakdown strength of these two oil/pressboard insulation systems at different ageing status were compared. The permittivity and ac breakdown strength of these two oil/pressboard insulation systems at different temperatures were also investigated. And a comparative result of the thermal stability behavior of these two oil/pressboard insulation systems with different ageing status was provided at last. Results show that though natural ester has higher absolute humidity and acidity during the long ageing period, the lower relative humidity of natural ester helps to keep its ac breakdown strength higher than mineral oil. The pressboard aged in natural ester also has higher ac breakdown strength than that aged in mineral oil. The lower relative permittivity ratio of natural ester impregnated paper to natural ester is beneficial to its dielectric strength. Using natural ester in transformer, the resistance to thermal decomposition of the oil/pressboard insulation system could be also effectively improved.Index Terms -Natural ester, mineral oil, pressboard, physicochemical, dielectric strength, thermal stability.

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Section: Acids Content Of Oil Impregnatedmentioning

confidence: 89%

Section: Acids Content Of Oilsmentioning

confidence: 99%

See 1 more Smart Citation

A comparative study of physicochemical, dielectric and thermal properties of pressboard insulation impregnated with natural ester and mineral oil

Liao

Hao

Chen

et al. 2011

IEEE Trans. Dielect. Electr. Insul.

190

View full text Add to dashboard Cite

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“…Several pretreatment methods have been reported, including alkalization, acidic activation, continuous disturbing and high-temperature treatment, etc. [34][35][36]. After exploring the different activation methods, we found that stirring cellulose in DMAc at 160°C for half an hour and adding anhydrate LiCl salt after the mixture was cooled to 80°C could obtain very clear and homogenous cellulose solution.…”

Section: Synthesis Of Hydrophobically Modified Cellulosementioning

confidence: 99%

Synthesis and characterization of hydrophobic long-chain fatty acylated cellulose and its self-assembled nanoparticles

Guo

Wang

et al. 2012

Polym. Bull.

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In this paper, a series of cellulose-based hydrophobic associating polymers were prepared by homogeneous acylation of microcrystalline cellulose with long-chain acyl chlorides including octanoyl, lauroyl, and palmitoly chlorides in the solvent of N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) using pyridine as acid scavenger. Through controlling the chain length of fatty acyl chlorides and the molar ratio of acyl chlorides vs anhydroglucose unit, the hydrophobic cellulose derivatives with degrees of substitution in the range of 0.02-1.75 were successfully obtained. The chemical structures and properties of these hydrophobic derivatives were characterized by elemental analysis, FT-IR, CP/MAS 13 C NMR, X-ray diffraction, and the thermogravimetry analysis. It was also found that, the cellulose-based polymers achieved an excellent solubility in organic solvents, such as benzene, methylbenzene, and pyridine, with the introduction of hydrophobic side chain into the cellulose backbone. Furthermore, it was found that these hydrophobic cellulose derivatives could self-assemble into spherical nanoparticles in aqueous solution, which indicates a tremendous potential of applications in pharmaceutical and medical fields.

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“…The DS of cellulose esters with long chain aliphatic acids has already been determined by spectroscopic techniques, such as NMR (Jandura et al 2000;Satge´et al 2002) and FTIR (Matsumura et al 2000), by elemental analysis (VacaGarcia et al 2001) and also by functional groups analysis, either by aminolysis of the ester groups with pyrrolidine followed by gas-chromatographic separation of the corresponding fatty acid derivatives (Samaranayake and Glasser 1993;Vaca-Garcia and Borredon 1999) or by alkaline hydrolysis of the ester groups followed by titration of the excess of alkali (Wang and Tao 1994;Chauvelon et al 1999).…”

Section: Introductionmentioning

confidence: 99%

An Efficient Method for Determination of the Degree of Substitution of Cellulose Esters of Long Chain Aliphatic Acids

et al. 2005

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The determination of the degree of substitution (DS) of fatty acid cellulose esters, representing a broad range of substituents (C 6 , C 12 , C 18 and C 22 ), was performed by alkaline hydrolysis of the ester groups and the quantification of fatty acids by gas chromatography-mass spectrometry (GC-MS) as their trimethylsilyl derivatives. The method was optimized and compared with established techniques for the DS determination (elemental analysis and alkaline hydrolysis/titrimetry). The results demonstrated that alkaline hydrolysis/ GC-MS is a rapid, reliable and powerful method for analysis of fatty acid cellulose esters, particularly when different acyl substituents are present.

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Acidic activation of cellulose and its esterification by long-chain fatty acid

Cited by 36 publications

References 18 publications

A comparative study of physicochemical, dielectric and thermal properties of pressboard insulation impregnated with natural ester and mineral oil

A comparative study of physicochemical, dielectric and thermal properties of pressboard insulation impregnated with natural ester and mineral oil

Synthesis and characterization of hydrophobic long-chain fatty acylated cellulose and its self-assembled nanoparticles

An Efficient Method for Determination of the Degree of Substitution of Cellulose Esters of Long Chain Aliphatic Acids

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