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Valorization of Kraft Lignin as Thickener in Castor Oil for Lubricant Applications

A. M. Borrero-López1, F. J. Santiago-Medina1, C. Valencia1,2*, M. E. Eugenio3, R. Martin-Sampedro3, J. M. Franco1,2

Department of Chemical Engineering, University of Huelva, El Carmen Campus, Agrifood Campus of International Excellence (ceiA3), 1071 Huelva, Spain
Pro2TecS – Chemical Process and Product Technology Research Center, University of Huelva, 21071 Huelva, Spain
INIA-CIFOR, Ctra de la Coruña, km 7.5. 28040, Madrid, Spain

*Corresponding author: email

Journal of Renewable Materials 2018, 6(4), 347-361.


It is known that large amounts of residual lignin are generated in the pulp and paper industry. A new alternative for Kraft lignin valorization, which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems, is proposed in this work. Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations, respectively. Moreover, both standardized penetration tests and tribological assays, usually performed in the lubricant industry, were carried out to evaluate the performance characteristics as lubricating greases. Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration. The thermorheological response evidenced a softening temperature of around 105 °C. The microstructure of these gel-like dispersions is composed of interconnected thin fibers, homogeneously distributed in castor oil. Moreover, the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.


Cite This Article

APA Style
Borrero-López, A.M., Santiago-Medina, F.J., Valencia, C., Eugenio, M.E., Martin-Sampedro, R. et al. (2018). Valorization of kraft lignin as thickener in castor oil for lubricant applications. Journal of Renewable Materials, 6(4), 347-361.
Vancouver Style
Borrero-López AM, Santiago-Medina FJ, Valencia C, Eugenio ME, Martin-Sampedro R, Franco JM. Valorization of kraft lignin as thickener in castor oil for lubricant applications. J Renew Mater. 2018;6(4):347-361
IEEE Style
A.M. Borrero-López, F.J. Santiago-Medina, C. Valencia, M.E. Eugenio, R. Martin-Sampedro, and J.M. Franco "Valorization of Kraft Lignin as Thickener in Castor Oil for Lubricant Applications," J. Renew. Mater., vol. 6, no. 4, pp. 347-361. 2018.

cc This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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