Tribological behaviour of novel chemically modified biopolymer-thickened lubricating greases investigated in a steel–steel rotating ball-on-three plates tribology cell

Abstract

In this work, model renewable and biodegradable lubricating greases based on castor oil and chemically modified biopolymers (methylcellulose, chitin and cellulosic pulp) were tribologically characterized in a steel–steel ball-on-plates tribological cell coupled to a controlled-stress rheometer, and the results were compared to those provided by conventional lithium and calcium soap-based greases. Viscous flow, sliding velocity sweep and transient friction tests were carried out and resulting wear scars in the steel plates were evaluated by means of scanning electron microscopy (SEM). Different frictional responses were found depending on the thickener, especially at high temperature. Excepting for most severe conditions, wear is negligible when using chemically modified chitin and methylcellulose-based greases as lubricants.This work is part of two research projects (CTQ2014-56038-C3-1R and TEP-1499) sponsored by MINECO-FEDER and Junta de Andalucia programmes, respectively. One of the authors (Rocio Gallego) has received a Ph.D. Research Grant (BES-2011-045029) from DIGICyT (MINECO). The authors gratefully acknowledge the financial support. Maria Teresa Cidade acknowledges the support of the Portuguese Foundation for Science and Technology through Project PEst-C/CTM/LA0025/2013 and The Portuguese Society of Rheology (SPR) for her stay in University of Huelva

AFM and SEM Assessment of Lubricating Grease Microstructures: Influence of Sample Preparation Protocol, Frictional Working Conditions and Composition

“…Samples C1-C6 were commercially available calcium and lithium soap-based greases whereas biopolymer-based model samples M1 and M2 were manufactured in the laboratory as described elsewhere [29,30]. Compositional details of the different lubricating greases analysed in this study as well as basic properties are listed in Table 1.…”

“…Samples were placed in a tribological cell coupled with a controlled-stress rheometer, Physica MCR-501 (Anton Paar, Austria), as described elsewhere [30]. At least three replicates of each test were performed at room temperature on fresh samples and resulting worked grease samples were analyzed by AFM.…”

Evaluation of lignin-enriched side-streams from different biomass conversion processes as thickeners in bio-lubricant formulations

“…At least five replicates of each test were done using fresh oleogel samples as lubricants. For the sake of comparison, the same tribological test was also performed under the same conditions using a commercial lithium lubricating grease [24].…”

Cellulose Pulp- and Castor Oil-Based Polyurethanes for Lubricating Applications: Influence of Streptomyces Action on Barley and Wheat Straws

“…As mentioned above, lower scar sizes were measured when cellulose pulps obtained from straw submitted to SSF treatments were employed, especially those resulting from the MDG301 action at its optimum temperature. Overall, outstanding wear values were obtained, lower than those found with commercial and other bio-based lubricating greases [51,52]. thickener, can penetrate in the lubricating contact, and the highest friction is just a consequence of the higher viscosity [18].…”