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3 results on '"Hajar Khaliliyan"'

1. Gellan residues on paper: quantification and implication for paper conservation

Author

Ute Henniges, Irene Brückle, Hajar Khaliliyan, and Stefan Böhmdorfer

Subjects
Gellan gel, Rigid gel, ATR-FTIR, Acid methanolysis, Residues, Paper conservation, Fine Arts, Analytical chemistry, QD71-142
Abstract

Abstract Gels prepared from the polysaccharide gellan are used for aqueous poulticing treatments in paper conservation when the application of water must be restricted. Optimal use of the rigid, yet shapeable gel requires direct contact with the paper surface, which carries the risk of gel residues on the treated surface. We used acid methanolysis as a destructive analytical method to detect rhamnose as a component of gellan, which was undetectable with ATR-FTIR spectroscopy. We show that there is a significant probability of leaving gellan residues on the paper. Conservators should be aware of this potential side effect when considering the use of gellan poultices in direct contact with paper objects.

Published
2024
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2. Analyzing the effects of thermal stress on insulator papers by solid-state 13C NMR spectroscopy

Author

Elisabeth Schwaiger, Antje Potthast, Thomas Rosenau, Paul Jusner, Jonas Simon, Florian Bausch, Markus Bacher, Sonja Schiehser, Ivan Sumerskii, and Hajar Khaliliyan

Subjects
Coalescence (physics), chemistry.chemical_compound, Materials science, Polymers and Plastics, chemistry, Transformer oil, Resonance, Insulator (electricity), Thermal treatment, Crystallite, Cellulose, Composite material, Kraft paper
Abstract

Million tons of cellulosic paper have been used for insulating coils in oil-filled electrical power transformers, thereby assuring the electricity supply for our societies. The high working temperatures in transformers constantly degrade paper insulators throughout their service life of up to 40 years. We approached the structural changes in oil-immersed cellulosic paper samples upon thermal stress in a study that compared unbleached softwood Kraft paper used as insulator paper with pure cotton cellulose paper. The model experiments used a thermal treatment in transformer oil at 170 °C for up to 14 days. The samples were characterized by means of 13C CP/MAS NMR spectroscopy, mainly based on deconvolution of the C4 resonance. An automated, fast, and reproducible C4 resonance deconvolution employing the “Peak Analyzer” tool of OriginPro 2020 (OriginLab Corporation, USA) was developed and used to exploit 13C CP/MAS NMR spectroscopy for the characterization of thermally stressed paper samples. Our results show that thermally induced structural changes depend heavily on the composition of paper, that hornification and coalescence of fibrils take place, and that the allomorph composition of cellulose crystallites is altered under the given conditions. Graphical abstract

Published
2021

3. Direct Quantification of Lignin in Liquors by High Performance Thin Layer Chromatography-Densitometry and Multivariate Calibration

Author

Ivan Sumerskii, Matthias Guggenberger, Christian Schuster, Josua T. Oberlerchner, Hajar Khaliliyan, Antje Potthast, Stefan Böhmdorfer, and Thomas Rosenau

Subjects
Kraft lignin, chemistry.chemical_compound, Chromatography, Renewable Energy, Sustainability and the Environment, Chemistry, General Chemical Engineering, Partial least squares regression, Environmental Chemistry, Lignin, Multivariate calibration, General Chemistry, High performance thin layer chromatography, Densitometry
Abstract

A method for lignin quantification is presented that is based on densitometry and multivariate calibration by partial least squares (PLS). Densitometry removes interferences otherwise caused by und...

Published
2020

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