Knowledge

Welcome to our knowledge centre. Here you can find a selection of resources and articles on our products and industries we are involved with.

Paper

Unsaturated Polyol Esters Used in Hydraulic Fluid Applications

This invention relates to unsaturated polyol esters that can be used in hydraulic fluid applications, including fire-resistant hydraulic fluid applications, …

This invention relates to unsaturated polyol esters that can be used in hydraulic fluid applications, including fire-resistant hydraulic fluid applications, marine hydraulic fluid applications, metalworking fluid applications, food grade fluid applications, and transformer fluid applications, and methods for making the same.

View abstract

Paper

Low Transition Temperature Mixtures and Lubricating Oils Containing the Same

Low transition temperature mixtures (LTTMs) comprising a eutectic mixture of a quaternary amine and a polyol such as glycol are …

Low transition temperature mixtures (LTTMs) comprising a eutectic mixture of a quaternary amine and a polyol such as glycol are provided. The LTTMs can provide various beneficial properties, such as highly desirable viscosity index, low glass transition temperatures, and/or high kinematic viscosities relative to the molecular weight of the mixture components. The mixtures can be advantageously used as co-base stocks in lubricating oil compositions.

View abstract

Paper

Capstan-like Mechanism in Hyaluronan-phospholipid Systems

Functionality of articular cartilage results from complex interactions between its molecular components. Among many biomolecules, two are of prime importance …

Functionality of articular cartilage results from complex interactions between its molecular components. Among many biomolecules, two are of prime importance for lubrication: hyaluronic acid (HA) and phospholipids (PL). The purpose of this study is to discuss a mechanism of interaction between these two components and how their synergies contribute to nanobiolubrication of articular cartilage. Preliminary molecular dynamics simulations have been performed to investigate these interactions by adopting a capstan-like mechanism of action. By applying a constant pulling force to both ends of a HA molecule, wrapped around a PL micelle, we viewed the rotation of the PL micelle. The simulations were performed upon two physicochemical constraints: force- and solvent-dependency. The results show the efficiency of rotation from intermolecular bond creation and annihilation. We found a direct relation between the available surface of the micelle and the magnitude of the force, which varies significantly through the unwinding. The movement of the attached molecules is characterized by a slide-to-roll relation, which is affected by the viscosity of the surrounding medium. As a consequence, two solvents were studied for specific force conditions and the molecular dynamics simulation exhibited double the slide-to-roll coefficient for the viscous solvent as compared to its low-viscosity limit.

View abstract

Paper

The Neuronal Encoding of Oral Fat by the Coefficient of Sliding Friction in the Cerebral Cortex and Amygdala

Fat in the diet contributes to the pleasant mouthfeel of many foods, but overconsumption may contribute to obesity. Here we …

Fat in the diet contributes to the pleasant mouthfeel of many foods, but overconsumption may contribute to obesity. Here we analyze what properties of fat in the mouth are sensed, by analyzing the responses of neurons in the macaque insular taste cortex, and two areas to which it projects the orbitofrontal cortex where the pleasantness of fat is represented, and the amygdala. We discovered that the firing rate responses of these fat-responsive neurons are correlated with the coefficient of sliding friction (CSF) and not with viscosity which reflects food thickness. Other, not fat-sensitive, neurons encoded viscosity and not the CSF. Neuronal population analyses confirmed that fat-responsive neurons conveyed information about the CSF but not about viscosity. Conversely the viscosity-sensitive neuronal population conveyed information about viscosity but not about the CSF. This new understanding of the representation of oral fat in the cerebral cortex and amygdala opens the way for the systematic development of foods with the pleasant mouthfeel of fat, together with ideal nutritional content and has great potential to contribute to healthy eating and a healthy body weight.

View abstract

Paper

On the Transient Decomposition and Reaction Kinetics of Zinc Dialkyldithiophosphate

Despite the ubiquitous use of the zinc dialkyldithiophosphate (ZDDP) as an antiwear additive, no complete information is yet available on …

Despite the ubiquitous use of the zinc dialkyldithiophosphate (ZDDP) as an antiwear additive, no complete information is yet available on its exact decomposition reactions and kinetics to form triboreactive protective films on contacting surfaces. This hinders the replacement of ZDDP with more environmentally friendly additives of similar antiwear capabilities. Using a multitechnique approach, this study shows that before the formation of a phosphate-rich protective film, the decomposition of ZDDP proceeds by forming intermediate zinc sulfide and sulfate species, which can be mechanically mixed with the iron oxides on the rubbing steel surfaces. The mixed sulfur-oxide layer can play different vital roles including binding the subsequently formed phosphate layers with the metal surface. These layers consist mainly of zinc thiophosphate of initially short chains, which are formed due to the excess concentration of metal oxide on the surface. As the concentration of the oxide decreases in the subsequent layers, the short chains start to polymerize into longer ones. The polymerization process follows first-order reaction kinetics with two distinctive phases. The first one is a fast transient burst phase near the steel surface, whereas the second phase dominates the formation process of the layers away from the substrate and is characterized by slow kinetics. The findings of this study provide new insights into the decomposition mechanisms of the currently most widely used antiwear additive and open future opportunities to find green alternatives with similar superior antiwear properties.

View abstract

Paper

Low Viscosity Lubricants Based on Methyl Paraffin Containing Hydrocarbon Fluids

A lubricating oil base stock including a lubricating oil base stock including from 5 to 50 wt % of 9-methylnonadecane …

A lubricating oil base stock including a lubricating oil base stock including from 5 to 50 wt % of 9-methylnonadecane and from 95 to 50 wt % of 9-methyl-11-octylheneicosane. The lubricating oil base stock has a relationship between Noack volatility at 250° C. as measured by ASTM D5800 (y) and kinematic viscosity at 40° C. as measured by ASTM D445 (x) that is less than y=2.15−0.765*ln(x). Also provided is a lubricating oil containing the lubricating oil base stock and one or more lubricating oil additives. A method for improving one or more of thermal and oxidative stability, deposit control and traction control in a lubricating oil by using as the lubricating oil a formulated oil containing the lubricating oil base stock and one or more lubricating oil additives is also provided.

View abstract

Paper

Lubricating Oil Magnesium Detergents and Method of Making and using Same

Disclosed is a magnesium alkylhydroxybenzoate detergent and a lubricating oil composition comprising said detergent. Engine oil is blended with various …

Disclosed is a magnesium alkylhydroxybenzoate detergent and a lubricating oil composition comprising said detergent. Engine oil is blended with various additives in order to satisfy various performance requirements. Additives that are able to bring multiple performance benefits while at the same time minimizing their debits are of utmost importance when formulating lubricants. For example, developing a detergent additive that has the ability to improve base number (BN) retention, reduce deposit formation, control oxidation, as well as tuning the frictional characteristics may negate or limit the need for additional additives that provide only these single performance benefits. A major challenge in engine oil formulation is developing lubricating oil compositions which simultaneously achieve benefits as those described above. Surprisingly, it has been found that lubricants formulated with magnesium alkylhydroxybenzoate detergents derived from isomerized normal alpha olefins show improvements in oxidation reduction, control deposits, BN retention, and friction performance.

View abstract

Paper

ZDDP-Additive Interactions in Engine Lubricant Formulations

This thesis describes the investigation of the solution phase interactions, and resulting coordination-, thermo- and tribo-chemistry, in binary antiwear (Zinc …

This thesis describes the investigation of the solution phase interactions, and resulting coordination-, thermo- and tribo-chemistry, in binary antiwear (Zinc Dialkyl DithioPhosphate – ZDDP) and organic friction modifier (OFM) additive formulations. The work probed in particular, the importance of OFM structure in dictating the thermolysis and tribochemical performance of ZDDP-OFM formulations, with the aim of facili- tating the selection or design of optimal additive combinations for engine lubricant applications. In this regard, Chapter 1 provides an introduction to the fundamentals of lubricant chemistry and lubricant formulation, with Chapter 2 briefly reviewing the current drivers that necessitate a more scientific approach to developing next-generation lubricant formulations. Chapter 3 describes the investigation of model ZDDP-pyridine interactions, whereby the pyridine scaffold served as an easily tunable N-donor moiety. Both 1:1 and 1:2 ZDDP-Py’ complexation reactions were identified, both of which occur via nitrogen-zinc coordination. Quantification of the contribution of steric (%Vbur) and electronic factors (pKaH) on the propensity of solution complexation (Ka), was achieved using 31P NMR spectroscopic titration data. Complexation was accompanied by a significant change in the zinc-bound dithiophosphate (DTP) binding mode, something that was monitored using Raman spectroscopy. Chapter 4 identified that the nature of ZDDP-OFM interactions mirror those found in the previously studied ZDDP-Py’ systems (via zinc-nitrogen complexation that is accompanied by a significant change in DTP binding bode). X-Ray crystallographic analysis of [Zn(k1-S-S2P(OiBu)2)2(C18-NH2)2] (7) unequivocally identified both the nitrogen-zinc coordination pathway and the OFM-induced change in binding mode previously inferred from solution 31P NMR spectroscopic data. The use of Raman spectroscopy for diagnosing DTP binding modes for ZDDP-OFM complexes was verified using the molecular structure of 7. Subsequent 31P NMR spectroscopic studies of other ZDDP-OFM combinations demonstrated that the strength of ZDDP-OFM solution interactions were highly dependent on the steric demands and presence of additional OFM donor sites. Chapter 5 describes the impact of the complexation reactions discussed, on the thermolysis and tribological performance of ZDDP-OFM systems. Thermal degradation path- ways were monitored using 31P NMR spectroscopy, while the tribological performance was assessed using the mini traction machine-space layer interferometry method (MTM-SLIM). The presence of amine-functional OFMs was observed to enhance the rate of ZDDP thermal degradation in all cases studied, with the extent of the rate enhancement observed correlating with the strength of ZDDP-OFM interaction. Subsequently, it was found that the ZDDP tribofilm formation rate did not correlate to the observed thermal stability in ZDDP-OFM systems. Chapter 6 explored some possible alternative synthetic methods for the preparation of zinc dialkyl diselenophosphates in an attempt to make use of the additional 77Se NMR spectroscopic handle that they would provide. Finally, in Chapter 7, the results obtained in Chapters 3-5 are described in a holistic manner, with the benefits of studying simplified single-component ZDDP-additive systems highlighted.

View abstract

Paper

Gellan Gum: A New Member in the Dysphagia Thickener Family

In this study, gellan gum (GG) (0.075–0.3 wt%) is proposed as a new dysphagia thickener and compared against commercial starch-based thickeners (modified starch with or …

In this study, gellan gum (GG) (0.075–0.3 wt%) is proposed as a new dysphagia thickener and compared against commercial starch-based thickeners (modified starch with or without gums, 5 wt%) and xanthan gum (XG, 0.5–1.0 wt%) using apparent viscosity, oral tribology using polydimethylsiloxane (PDMS) ball-on-disc set up and ζ-potential measurements. The measurements were conducted in presence of artificial saliva containing mucin with or without α-amylase at 37 °C. Viscosity results suggested that the commercial starch-based thickeners behaved like water in orally relevant shear, largely associated with the hydrolysis of modified starch by α-amylase, whereas, XG and GG showed no responsiveness to α-amylase. In the case of oral tribology, artificial saliva containing mucin adsorbed to the PDMS surfaces reducing friction as compared to water. The increase in boundary friction coefficients in commercial starch-based thickeners was likely associated with α-amylase-induced hydrolysis, increasing the PDMS-PDMS asperity contacts. Interestingly, the tribological behaviour of XG and GG was dictated mainly by viscous lubrication. However, in simulated oral conditions, the increase in friction coefficients in presence of XG and GG was influenced by depletion of artificial saliva from the PDMS surfaces due to electrostatic interaction between the gums and mucin. A combination of rheological and tribological techniques in orally relevant conditions appears as a reliable approach to understand the potential of GG (0.3 wt%) to act as a dysphagia thickener that offers similar mechanical properties as XG (1.0 wt%) at a lower concentration. Extensional viscosity measurement of GG is needed to understand its applications in dysphagia management.

View abstract