Thickening Castor Oil with a Lignin-Enriched Fraction from Sugarcane Bagasse Waste via Epoxidation: A Rheological and Hydrodynamic Approach

Abstract

Thickening vegetable oils to different extents is of great interest in the design and development of new bio-based lubricant formulations, as achieving a wide range of rheological properties is crucial to the successful replacement of petroleumbased traditional counterparts. With this aim, the influence of epoxidation degree, modified by altering the reaction conditions, on the viscous flow properties of epoxidized castor oil was investigated together with the incorporation of a lignin-enriched fraction from sugarcane bagasse waste to more extensively modify the rheological properties, thereby valorizing this waste fraction. Oil thickening was achieved by promoting the cross-linking between the epoxidized oil and the lignin-enriched fraction that enables the compatibilization of both components. Castor oil epoxidation was assessed by means of standard volumetric titration methods and infrared spectroscopy. In addition, a fully rheological characterization of both epoxidized and lignin-thickened castor oils was carried out. A hydrodynamic approach was also followed, aiming to provide an estimation of the Mark−Houwink−Sakurada parameters and relate the intrinsic viscosity with the average molecular weight of the resulting epoxidized castor oil/lignocellulose macromolecular compounds. The chemical interaction between castor oil and the lignocellulosic material increased as the extent of epoxidation was increased, yielding a variety of rheological responses from Newtonian liquids of increasing viscosities (from around 1 to 500 Pa•s) to viscoelastic liquids.

Lignocellulosic Materials for the Production of Biofuels, Biochemicals and Biomaterials and Applications of Lignocellulose-Based Polyurethanes: A Review

“…In another study, Hua et al [ 187 ] created lignin-based green lubricants with excellent properties in diamond-like carbon-steel contact compared to commercial lubricants, showing lignin-based lubricants to be useful on surfaces with different characteristics. Cortés-Triviño et al [ 188 ] tested a lignin-enriched residue coming from sugarcane bioethanol production to further valorise it by mixing with castor oil epoxidised at different degrees, showing the possibility to tune the rheological and lubricant properties thereof of the mentioned mixtures. The production of nanofibres from lignin by using the electrospinning technique has likewise permitted the use of these materials as oil structuring [ 189 ].…”

Synthesis and Characterization of Thermally Stable Lignosulfonamides

“…Unmodified lignin exhibits many valuable features, such as biodegradability, good thermal stability, anti-oxidant and anti-microbial properties [ 22 ], and UV-ray absorbance [ 23 ]; employing various methods of chemical modification allows for further enhancement of the inherent lignin properties. Lignin may undergo esterification [ 24 ], etherification [ 25 ], epoxidation [ 25 , 26 ], amination [ 27 , 28 ] and other reactions in accordance to the desired outcome—whether obtaining sorbents for the selective absorption of dyes [ 29 , 30 , 31 , 32 ], antibiotics [ 33 ] or heavy metals [ 32 , 34 , 35 , 36 ] from wastewater or dyestuff effluents, manufacturing of additives for epoxy resins [ 37 , 38 ], polyurethane systems [ 37 , 39 , 40 , 41 ], wood adhesives [ 42 , 43 ], additive for asphalt binders [ 44 ], lubricants [ 45 ], surfactants [ 46 ], carbon fibers [ 47 , 48 ] or even sunscreens [ 49 ]. The presently explored directions of development of the applicability of technical lignins, whether in the form of hydrogels or other forms, mainly focus on four fields of potential utilization: biomedical, agriculture, environment, and electronics [ 50 ].…”

Study on Frictional Properties of Fine Powder Materials

“…According to the history of the development of lubricant additives, nanoparticles are a relatively new class of additives to lubricant materials. It includes colloidal solid particles contained in lubricant oil [12][13][14][15][16]. The main components of nano oil materials are lubricant/basic oil, a nano oil additive, and a surfactant.…”

“…The compositions of additives to oils are continuously improved and their properties are enhanced [6][7][8][9][10]. Some studies are aimed at developing new environmentally friendly materials [11][12][13][14].…”