Isocyanate-Functionalized Chitin and Chitosan as Gelling Agents of Castor Oil

Molecules

Rocío Gallego¹  Jesús F. Arteaga¹  Concepción Valencia¹ 

[1] Department of Chemical Engineering, Physical Chemistry and Organic Chemistry, University of Huelva, Campus El Carmen, Campus ceiA3, 21071 Huelva, Spain

关键词: chitin;    chitosan;    castor oil;    isocyanate;    lubricating grease;    rheology;   

DOI  :  10.3390/molecules18066532

来源: mdpi

【 摘 要 】

The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO–functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI), and the other by using chitin instead of chitosan. These polymers were characterized through ¹H-NMR, FTIR and thermogravimetric analysis (TGA). Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS) measurements. The evolution and values of the linear viscoelasticity functions with frequency for –NCO–functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.