Lubricity Improver Research Articles

Lubricity improvement of the raw jojoba oil with TiO2 nanoparticles as an additives at different loads applied

This study involves TiO2 nanoparticles for the improvement of the lubricity of the oil. The process is accomplished by using DUCOM tribometer. During this study, different loads are applied at constant temperature during the whole process. Various concentrations of the nanoparticles are considered which are selected based on the previous studies. The minimum coefficient of friction was obtained when nanoparticles are added up to 0.3 percent. During higher amount of nanoparticles addition, more wear of the disc occurs. At 0.3 percentage of nanoparticles, improved results in terms of wear of the parts have been observed with comparison to the raw jojoba oil.

Chemical and kinetic insights into fuel lubricity loss of low-sulfur diesel upon the addition of multiple oxygenated compounds

Fatty acid methyl esters (FAMEs, the primary components of biodiesel) can improve the lubricity of low-sulfur diesel (LSD); however, detailed investigations into biodiesel components with various chain lengths (e.g., short-chain FAMEs) are rarely discussed. Additionally, the complex lubricity behavior with FAMEs containing free fatty acids or antioxidants is unknown. Our results showed that lauric acid methyl ester brings limited fuel lubricity improvement to LSD. The presence of fatty acids and antioxidants facilitated the formation of different frictional products on wear tracks or eliminated wear-resistive products. We further interpret fuel lubricity results by resolving kinetic features of measured electrical contact resistances and chemical composition profiles within wear tracks from standardized tests. Beyond understanding how oxygenated compounds affect fuel lubricity, we expect that the analytical approaches demonstrated in this work can shed light on other fuel lubricity related problems.

Interferential current: a new option for the treatment of sexual complaints in women with premature ovarian insufficiency using systemic hormone therapy: a randomized clinical trial

The aim of the study was to evaluate the efficacy of interferential current (IC) in the sexual function of women with premature ovarian insufficiency (POI) using systemic hormone therapy (HT), compared to topical estriol. A randomized clinical trial with 40 women with POI using systemic HT, who were sexually active and referred for dyspareunia and reduction of lubrication. The women were divided into two treatment groups for 4 weeks: IC group (eight electrotherapy sessions twice a week); or E group (estriol vaginal cream, daily application, 0.5 mg/d). The Female Sexual Function Index was used to evaluate pre-/posttreatment sexual function. Mean age was 37.13 ± 7.27 years and mean treatment time with HT was 8.20 ± 8.73 years, similar data for both groups. There was an improvement in global sexual function, lubrication, and pain domains for both treatments. The differences between the pre-/posttreatment lubrication scores were respectively 0.75 ± 3.31 (P = 0.014) for IC and 1.16 ± 1.22 (P < 0.001) for estriol, whereas for dyspareunia the differences were 1.00 ± 1.47 (P = 0.005) for IC, and 0.68 ± 1.30 (P = 0.006) for estriol. There was no pre-/posttreatment difference for the desire and arousal domains. Only in the IC group did orgasm (difference 0.90 ± 1.42, P = 0.010) and satisfaction improve (difference 0.70 ± 1.28, P = 0.021). The use of perineal IC seems to be a new option for women with POI using systemic HT and presenting with sexual complaints, leading to an improvement in pain, lubrication, satisfaction, and orgasm.

Performance of Al2O3-SiO2/PAG employed composite nanolubricant in automotive air conditioning (AAC) system

Automotive Air conditioning (AAC) system is the contributor of harmful gasses emission and global warming. In order to solve the issues, investigation on potential improvement in lubrication used in air conditioning system is done to improve the system performance and efficiency. The performance of AAC system namely cooling capacity, compressor work, coefficient of performance (COP) and power consumption was investigated by comparing pure lubricant and Al2O3-SiO2/PAG nanolubricants. Performance of AAC by using different ranges of refrigerant charges (95 to 155 g) and speeds (1200 and 1800 rpm) was investigated. The result shows that the cooling capacity and COP of pure lubricant were relatively lower than Al2O3-SiO2/PAG nanolubricants. The compressor work and power consumptions of Al2O3-SiO2/PAG nanolubricants were greatly reduced. Cooling capacity and COP are enhanced by 102.99% and 23% respectively. The compressor work and power consumption are reduced by 25.9% and 28.24% respectively. From the results, nanolubricants gives more advantages in AAC performance over pure lubricant. Therefore, Al2O3-SiO2/PAG composite nanolubricants is recommended to be used as the compressor lubrication to enhance AAC performances system.

Improving the lubricity of a bio-lubricating grease with the multilayer graphene additive

The natural wax separated from the agro-waste resource is a feasible and sustainable biolubricant. Investigation on the lubrication behaviors of this new renewable lubricant is attractive. In this work, a multilayer graphene was introduced into a wax obtained from the non-medicinal part of Codonopsis pilosula for the purpose of the lubricity improvement. A reciprocating ball-on-disc configuration and AISI 52100 self-mated sliding-pairs were selected for tribological evaluation. The results indicated that the addition of multilayer graphene improves the load-carrying capacity and high temperature lubricity of the natural wax.

The effect of transobturator tape operation on sexual functions of a patient with stress urinary incontinence and patient's spouse

This prospective study aimed to investigate the effects of transobturator tape (TOT) procedure on patients with stress urinary incontinence (SUI) and their spouses' sexual function. A total of 157 patients with SUI who underwent TOT operation between January 2017 and May 2019 and their spouses were included. All patients enrolled filled out the Incontinence Impact Questionnaire (IIQ-7), the Urogenital Distress Inventory (UDI-6), the Female Sexual Function Index (FSFI), and patients' spouses filled out International Index of Erectile Function (IIEF-5) before surgery and 6 months after the surgery. The mean value of IIQ-7 and UDI-6 questionnaires in the sixth month after the TOT surgery was lower than the mean scores of these questionnaires before surgery (P < .001). The mean value of the FSFI score was 21.84 ± 1.76 before the surgery and 25.43 ± 1.84 in the sixth month after the surgery (P < .001). There was a significant improvement in desire, arousal, lubrication, orgasm, satisfaction, and pain scores on the FSFI domains (P < .001, <.001, <.001, <.001, <.001 and <.05, respectively). The mean value of the IIEF-5 score of patients' spouses was 48.31 ± 5.23 before surgery and 57.87 ± 7.22 in the sixth month after the surgery (P < .001). Significant improvement was observed in IIEF-5 score regarding sexual desire, intercourse satisfaction, and overall satisfaction domains (P = .012, .002, and .006, respectively). TOT surgery significantly improves the sexual functions of both patients and their spouses.

HFRR and SL-BOCLE Lubricity of Paraffinic Diesel Fuels Considering Different Origins and Final Formulations with Biodiesels and Additives

The lubricant characteristics of different paraffinic diesel fuel formulations, including biodiesel and lubricity improvers, were tested and compared with the characteristics of conventional middle...

Effect of hBN and SiC addition on laser assisted processing of ceramic matrix composite coatings

To develop TiB2–TiN–SiC and TiB2–TiN–SiC-hBN based ceramic matrix composite coatings with superior mechanical and tribological properties suitable for engineering applications, a high-power CW-laser is used to initiate chemical reactions in precursor powder mixtures (TiO2, SiO2, hBN and graphite) of several compositions preplaced over AISI1025 steel substrates. Here, coatings’ stoichiometric compositions (TiB2–TiN–SiC) fabricated through in-situ synthesis are altered by adding SiC and additional amount hBN in the precursor at variable weight ratios. Presence of variable amount of SiC in TiB2–TiN–SiC and hBN in TiB2–TiN–SiC-hBN composites imparts several microstructural, mechanical and tribological property combinations. In this study, an attempt has been made to experimentally evaluate the optimum range of hBN and SiC additions to obtain highest improvements in lubrication and wear resistance respectively.

Ash Catalyzed Synthesis of Long-Chain Dialkyl Carbonates Through Carbonyl Exchange Reaction

Present work is focused on development of methodology involving utilization of cost effective, highly effective heterogeneous catalyst prepared from wood ash for carbonyl exchange reaction between long chain alcohols and diethyl carbonate to produce long-chain dialkyl carbonates. Whereas long-chain dialkyl carbonates are being explored as value added compounds as they are environmentally safe and non-corrosive in nature and useful in diesel as cetane improvers, lubricants and used in cosmetics. Thermal treatment (calcination) of wood ash was carried out at 500 and 800 °C temperatures and studied the activity of resulted catalyst towards the synthesis of long-chain dialkyl carbonates through carbonyl exchange reaction. The prepared catalyst was characterized by analytical techniques for surface morphology, crystalline phases and textural characteristics. In the present study, maximum yield of long-chain dialkyl carbonates (81%) was achieved using heterogeneous wood ash catalyst at 10 wt% of reactants and at temperature of 120 °C. The synthesized products were characterized by analytical techniques like infrared (IR), nuclear magnetic resonance (NMR), gas chromatography and mass spectroscopy respectively. Applications of prepared long-chain dialkyl carbonates in ultra low sulphur diesel (ULSD) have been explored as lubricity improvers and cetane number improvers.

Risk factors of postoperative sexual function in patients with urethral diverticulum and their partners: A cohort study of 83 women.

ABSTRACTIntroduction and Objective:Several studies have focused on the treatment and recurrence of urethral diverticulum (UD). However, few investigations have addressed sexual function in patients with UD. Therefore, we sought to examine sexual function in women affected by UD.Materials and Methods:There were 108 accepted cases involving transvaginal diverticulectomy at our institution. Ultimately, 83 women were included for further analysis, only 61 of these women had sexual partners. We collected data for the Female Sexual Function Index (FSFI) from the female patients and the Male Sexual Health Questionnaire (MSHQ) from their male partners before and after surgery.Results:Preoperatively, the UD size affected the female patient's arousal and lubrication (p=0.04), and the UD location affected their satisfaction. However, no significant between-group differences were found in the total FSFI score. For all women, sexual activity improved after surgery (p=0.0087). In addition to improvements in arousal for women with a large UD, improvements in lubrication were affected by the UD size, number and shape, increases in satisfaction scores were impacted by the UD location and shape, and pain relief was linked to the UD number and shape. Analysis of the MSHQ results revealed no between-group differences among the male partners.Conclusion:Only the UD size and location affected sexual function in women with a small UD. Surgery could improve female sexual function but did not affect the sexual function of the patient's partners.

Interfacial Assembly Behavior of Alkylamine-Modulated Graphene Oxide with Different Oxidation Degrees.

Multitudinous studies have been carried out on the controllable functionalization and performance evaluation of graphene oxide (GO). In this study, the correlation between the amount of grafted alkylamine on GO and its interfacial assembly behavior at liquid-liquid and liquid-solid interfaces was studied. GO was modified with n-octylamine through basal functionalization (bGO). The grafting amount of alkylamines was regulated using two GOs varied in oxidation degree (GO_L and GO_H). A study on the oil-water interfacial behaviors shows that bGO_L has better ability to modulate the interfacial tension than that of bGO_H. Grafting alkylamine on GO will not only increase the interaction strength with oil while weaken that with water but also do damage to the graphene lattice and weaken the interaction of π-π stacking; therefore, bGO_L displays a broader capability to modulate interfacial tensions than that of bGO_H. The bGO-based Pickering emulsion was prepared, and the interfacial behavior at the liquid-solid interface was investigated. A study on the interfacial anti-rust performances demonstrates that grafted alkyl chains in bGOs can form more compact and ordered protective films on the metal surface and enhance the hydrophobicity as a result of the similar structure to oil in the emulsion system, which makes Pickering emulsions show better anti-rust abilities than water dispersions. Meanwhile, the bGO_H emulsion shows a better anti-rust property than that of the bGO_L emulsion. A study on the interfacial tribological behaviors shows that the lubricity of bGO_L is better than that of bGO_H. X-ray photoelectron spectroscopy analysis shows that a high content of C-O-C/C-OH in lubricating films contributes to the improvement of lubricity. The modulated interfacial assembly properties of GO at both liquid-liquid and solid-liquid interfaces suggest their potential applications in surface protection, lubrication, controllable drug deliveries, absorption and separation, nanocomposites, and catalyst fields.

Adsorption of lubricity improver additives on sliding surfaces

Lubricity improver additives are adsorbed on sliding surfaces and form boundary films. Although for most additives, the films are monolayers, multilayer adsorption does occur in tribological contacts. However, to date, the isotherms adopted to study the adsorption thermodynamics for tribological systems are limited to monolayer films. To address this, the original Brunauer–Emmett–Teller (BET) gas adsorption isotherm was modified for use in dilute liquid solutions. The modified BET isotherm was used to fit experimental wear data collected using high frequency reciprocating rig (HFRR) for ultra-low sulphur diesel (ULSD) fuels containing trace levels of commercial lubricity improving additives. The results suggested that for certain additives in ULSD, the boundary film is multilayer.

Improvements in the mixed elastohydrodynamic lubrication and in the efficiency of hypoid gears

In this paper, the influence of the manufacturing parameters on the conditions of mixed elastohydrodynamic lubrication is investigated. On the basis of the obtained results, recommendations are formulated to improve the mixed EHL and the efficiency of face-milled hypoid gears. A full numerical analysis of the mixed EHL in hypoid gears is applied. The equation system and the numerical procedure are unified for a full coverage of all the lubrication regions, including the full film, mixed, and boundary lubrication. In the hydrodynamically lubricated areas, the calculation method employed is based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace's equations. In the asperity contact areas, the Reynolds equation is reduced to an expression equivalent to the mathematical description of dry contact problem. The real geometry and kinematics of the gear pair based on the manufacturing procedure are applied; thus, the exact geometrical separation of the mating tooth surfaces is included in the oil film shape, and the real velocities of these surfaces are used in the Reynolds and energy equations. The transient nature of gear tooth mesh is included. The oil viscosity variation with respect to pressure and temperature and the density variation with respect to pressure are included. The non-Newtonian behaviour of the lubricant is considered. Using this model, the pressures, film thickness, temperatures, and power losses in the mixed lubrication regime are predicted. The effectiveness of the presented method is demonstrated by using hypoid gear examples.

A pilot study of soft gel technology: a new vaginal device to improve the symptomatology of vulvovaginal atrophy in post-partum, menopause and in patients with recurrent vulvovaginitis.

This is a pilot study to evaluate the effectiveness of the treatment with Vaginal Soft gels technology in the improvement of common signs and symptoms in postmenopausal, postpartum and with recurrent vulvovaginitis patients. These conditions may cause the onset of Vulvovaginal Atrophy (VVA) with effects on sexual activity, self-confidence and daily activities. The main symptoms are itching, irritation and dryness. Many therapies have been evaluated and almost all those without hormonal component have shown poor results. Women diagnosed with severe VVA from January to September 2018 were recruited. The study groups were composed of 25 postmenopausal women, 30 post-partum women and 30 women with recurrent vulvovaginitis. For each group, patients were randomized 1:1 among those who carried out the experimental treatment and those that did not perform it. The efficacy of treatment was evaluated with a clinical visit in which Vaginal Health Index (VHI) was estimated. The symptomatology was determined through the questionnaire Female Sexual Function Index (FSFI). A significant improvement has been shown with regard to the sexual function (orgasm, lubrification, pain) in patients who performed the treatment. A significant increase in VHI has been evaluated in postmenopausal patients (4 months p=0.054, 6 months p=0.005) and in recurrent vulvovaginitis but not in post-partum patients (4 months p=0.681, 6 months p=0.109). An improvement of lubrication, satisfaction, orgasm, pain, as well as dyspareunia, was observed in the three study groups. In this pilot study the treatment with soft gels seems to be effective in improving sexual health and atrophy being a treatment available for all types of patients thanks to the absence of systemic and local side effects. It is an excellent alternative especially for patients who cannot use hormones. These findings must be confirmed by larger and randomized further studies.

Selection of Blends of Diesel Fuel and Advanced Biofuels Based on Their Physical and Thermochemical Properties

Current policies focus on encouraging the use of renewable energy sources in transport to reduce the contribution of this sector to global warming and air pollution. In the short-term, attention is focused on developing renewable fuels. Among them, the so-called advanced biofuels, including non-crop and waste-based biofuels, possess important benefits such as higher greenhouse gas (GHG) emission savings and the capacity not to compete with food markets. Recently, European institutions have agreed on specific targets for the new Renewable Energy Directive (2018/2001), including 14% of renewable energy in rail and road transport by 2030. To achieve this, advanced biofuels will be double-counted, and their contribution must be at least 3.5% in 2030 (with a phase-in calendar from 2020). In this work, the fuel properties of blends of regular diesel fuel with four advanced biofuels derived from different sources and production processes are examined. These biofuels are (1) biobutanol produced by microbial ABE fermentation from renewable material, (2) HVO (hydrotreated vegetable oil) derived from hydrogenation of non-edible oils, (3) biodiesel from waste free fatty acids originated in the oil refining industry, and (4) a novel biofuel that combines fatty acid methyl esters (FAME) and glycerol formal esters (FAGE), which contributes to a decrease in the excess of glycerol from current biodiesel plants. Blending ratios include 5, 10, 15, and 20% (% vol.) of biofuel, covering the range expected for biofuels in future years. Pure fuels and some higher ratios are considered as well to complete and discuss the tendencies. In the case of biodiesel and FAME/FAGE blends in diesel, ratios up to 20% meet all requirements set in current fuel quality standards. Larger blending ratios are possible for HVO blends if HVO is additivated to lubricity improvers. For biobutanol blends, the recommended blending ratio is limited to 10% or lower to avoid high water content and low cetane number.

Improvement of Diesel Lubricity by Chemically Modified Tung-Oil-Based Fatty Acid Esters as Additives

Diesel fuel lubricity has been a concern of diesel fuel injection equipment manufacturers for many years. The problem has drawn attention because of the reduction in lubricity associated with the e...

Using Polymers to Impart Lubricity and Biopassivity to Surfaces: Are These Properties Linked?

AbstractPolymer brushes have been widely applied for the reduction of both friction and non‐specific protein adsorption. In many (but not all) applications, such as contact lenses or medical devices, this combination of properties is highly desirable. Indeed, for many polymer‐brush systems, lubricity and resistance to biofouling appear to go hand in hand, with modifications of brush architecture, for example, leading to a similar degree of enhancement (or degradation) in both properties. In the case of poly(ethylene glycol) (PEG) brushes, this has been widely demonstrated. There are, however, examples where this behavior breaks down. In systems where linear brushes are covalently crosslinked during surface‐initiated polymerization (SIP), for example, the presence and the chemical nature of links between grafted chains might or might not influence biopassivity of the films, while it always causes an increment in friction. Furthermore, when the grafted‐chain topology is shifted from linear to cyclic, chemically identical brushes show a substantial improvement in lubrication, whereas their protein resistance remains unaltered. Architectural control of polymer brush films can provide another degree of freedom in the design of lubricious and biopassive coatings, leading to new combinations of surface properties and their independent modulation.

Restoration Effect and Tribological Behavior of Hyaluronic Acid Reinforced with Graphene Oxide in Osteoarthritis.

Osteoarthritis (OA) is an unavoidable degenerative disease of the human body. A relatively efficient and desirable treatment exists that leads to the ecological restoration of cartilage through the adjustments of the micro-environment of the human body and relies on its self-repairing ability. In the present study, lubricants were injected into the knee joints of rats. Hyaluronic acid (HA) reinforced with graphene oxide (GO) provided a lubricating condition for cartilage repair, as well as played an important role in the regulation of the microenvironment in the joint cavity. The experimental results demonstrated that the stability of HA lubricant reinforced with GO was dependent on the presence of oxygen-containing functional groups on the graphite oxide nano-sheets. The GO could be evenly distributed on the joint surface in the form of a solid lubrication film and was able to decrease the articular cartilage necrosis and the ratio of MMP-3/TIMP-1 through TIMP-1 activity increase. The HA lubricant reinforced with GO demonstrated an apparent antifriction effect on the joint surface, providing a stable environment for cartilage repair. It was also conducive to long-term lubrication improvement. The adjustment of micro-environment between the cartilage friction interfaces might contribute to the treatment of osteoarthritis through ecological restoration.

Experimental investigations of wall jet droplet impact on spray impingement fuel film formation

The understanding of fuel spray impingement phenomenon and its impact of film formation on wall are significant for engine related applications, such as emission reduction and lubrication improvement, etc. However, the impingement phenomenon of the airborne droplets in the wall jet moving parallel to the wall has not been fully understood yet, especially for the fact that negligible amount of fuel film is formed underneath the wall jet. In this experimental research, various laser diagnostic techniques, including laser-induced fluorescence, Mie scattering, phase Doppler interferometry, and particle imaging velocimetry were utilized to capture both macroscopic and microscopic behavior of the spray impingement process. It was found that droplets in the spray with a high tangential velocity may be governed by the lift force induced by the boundary layer near the plate, gliding away without impinging the wall and forming wall film. Based on the observations, a modified impingement criterion is proposed to incorporate such gliding effects to improve the current understanding of droplet-wall interactions.

Nonionic polyol esters as thinner and lubricity enhancer for synthetic-based drilling fluids

This study evaluates the performance of polyol esters as thinners and lubricity enhancers in invert emulsion synthetic-based drilling mud (SBM). Three types of polyol esters, namely pentaerythritol ester (PEE), trimethylolpropane ester (TMPE), and neopentyl glycol ester (NPGE), were prepared at various concentrations of 1, 2, and 3% (v/v) in SBM. The results showed that polyol esters reduced the rheological properties of the drilling mud, such as yield point and gel strength, after the hot rolling test at 135 °C. The rheology data was fitted to the Herschel-Bulkley model to describe the shear thinning behaviour of drilling mud. The model parameters showed that the polyol ester resulted in lower yield stress of SBM, which indicated lower forces are needed to initiate a fluid to move. Their relative effectiveness as a lubricity enhancer was evaluated by measuring the coefficient of friction (COF), wear scar diameter, and scar topography. It was found that polyol esters reduced the COF of SBM by 22% at a concentration of 1% (v/v). PEE provided the best friction reduction and anti-wear performance due to a higher number of the ester group and molecular weight, in comparison with NPGE and TMPE. The lubricity improvement for SBM is recently required by off-shore regulations.