Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations
Considerable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening...
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doaj-ad94b9e22be041ca854c110b6ad10cd12020-11-25T01:49:23ZengMDPI AGPolymers2073-43602018-06-0110667010.3390/polym10060670polym10060670Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant FormulationsEsperanza Cortés-Triviño0Concepción Valencia1Miguel A. Delgado2José M. Franco3Pro2TecS-Chemical Product and Process Technology Centre, University of Huelva, 21071 Huelva, SpainPro2TecS-Chemical Product and Process Technology Centre, University of Huelva, 21071 Huelva, SpainPro2TecS-Chemical Product and Process Technology Centre, University of Huelva, 21071 Huelva, SpainPro2TecS-Chemical Product and Process Technology Centre, University of Huelva, 21071 Huelva, SpainConsiderable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening agent to formulate eco-friendly lubricating greases. In this work, alkali lignin (AL) was chemically modified with poly(ethylene glycol) diglycidyl ether (PEGDE). Afterwards, the epoxidized lignin was properly dispersed in castor oil (CO) in order to obtain an oleogel for lubricant applications. The epoxidized lignins were characterized by means of epoxy index determination, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The epoxide-functionalized lignin-based oleogels were analyzed from both rheological and tribological points of view. It was found that the viscosity, consistency and viscoelastic functions of these oleogels clearly increased with the epoxy index of the epoxide-modified lignin compound. Thermo-rheological characterization of these oleogels revealed a slight thermal dependence of the viscoelastic moduli below 100 °C, but a significant softening above that critical temperature. In general, these oleogels showed low values of the friction coefficient under the mixed lubrication regime as compared to the neat castor oil.http://www.mdpi.com/2073-4360/10/6/670epoxide-functionalized lignincastor oillubricating greasesrheologytribology |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Esperanza Cortés-Triviño Concepción Valencia Miguel A. Delgado José M. Franco |
spellingShingle |
Esperanza Cortés-Triviño Concepción Valencia Miguel A. Delgado José M. Franco Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations Polymers epoxide-functionalized lignin castor oil lubricating greases rheology tribology |
author_facet |
Esperanza Cortés-Triviño Concepción Valencia Miguel A. Delgado José M. Franco |
author_sort |
Esperanza Cortés-Triviño |
title |
Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations |
title_short |
Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations |
title_full |
Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations |
title_fullStr |
Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations |
title_full_unstemmed |
Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations |
title_sort |
modification of alkali lignin with poly(ethylene glycol) diglycidyl ether to be used as a thickener in bio-lubricant formulations |
publisher |
MDPI AG |
series |
Polymers |
issn |
2073-4360 |
publishDate |
2018-06-01 |
description |
Considerable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening agent to formulate eco-friendly lubricating greases. In this work, alkali lignin (AL) was chemically modified with poly(ethylene glycol) diglycidyl ether (PEGDE). Afterwards, the epoxidized lignin was properly dispersed in castor oil (CO) in order to obtain an oleogel for lubricant applications. The epoxidized lignins were characterized by means of epoxy index determination, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The epoxide-functionalized lignin-based oleogels were analyzed from both rheological and tribological points of view. It was found that the viscosity, consistency and viscoelastic functions of these oleogels clearly increased with the epoxy index of the epoxide-modified lignin compound. Thermo-rheological characterization of these oleogels revealed a slight thermal dependence of the viscoelastic moduli below 100 °C, but a significant softening above that critical temperature. In general, these oleogels showed low values of the friction coefficient under the mixed lubrication regime as compared to the neat castor oil. |
topic |
epoxide-functionalized lignin castor oil lubricating greases rheology tribology |
url |
http://www.mdpi.com/2073-4360/10/6/670 |
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