Safe Lubricants Research Articles

Performance of Polymer Composites Lubricated with Glycerol and Water as Green Lubricants

The study analysed the tribological performance of five different polymer composites: polyetheretherketone reinforced with 30% carbon fibres—PEEK CF30, polyetheretherketone reinforced with 10% carbon fibres, 10% graphite and 10% polytetrafluoroethylene—PEEK MOD, polytetrafluoroethylene reinforced with 25% carbon fibres—PTFE CF25, polyoxymethylene with 30% carbon fibres—POM CF30 and ultra-high molecular weight polyethylene—UHMW PE. The polymers were tested under the sliding regime of a reciprocating stainless-steel ball on a polymer disc, with test parameters expected for hydraulic valves. Two environmentally safe lubricants were used: glycerol and water. The selected polymer materials and their tribological properties were compared based on the coefficient of friction and the specific wear rate. The worn surfaces were examined using scanning electron microscopy, and the transfer film was analysed using the energy dispersive spectroscopy technique. When tested in glycerol, a comparable and low coefficient of friction was measured for all polymers (~0.02). At the same time, a significantly lower coefficient was measured for all polymers in glycerol compared to water-lubricated conditions (~0.06–0.22). The polymers differed in the measured specific wear rate, which increases significantly in water for all polymers. A lower specific wear rate was measured for three polymers with higher microhardness: PEEK CF30, PEEK MOD and POM CF30. In water, PEEK CF30 showed superior tribological properties under harsh conditions but was well followed by POM CF30, which showed the most intense transfer film.

Risk assessment for hazardous lubricants in machining industry.

Knowing that over two-thirds of lubricant disposals return to the environment with no purification process, adequate strategies are demanded to reduce their risks. For this reason, the main focus of the present study is to describe an environment-friendly approach. In the first part, two widely used lubricants (mineral-based and vegetable-based) were introduced, and the reasons for their hazards were investigated. The composition of mineral-based lubricant was characterized by x-ray fluorescence elemental analysis. The result showed the presence of phosphorus, chlorine, and zinc dialkyl dithiophosphate in its composition that many scholars considered them to be the leading risk factor in the chemical composition of mineral-based lubricants. It has been focused on the potential risks of vegetable-based lubricants, which many researchers have identified as a safe lubricant. The Pseudomonas microbe was cultivated in the vegetable-based sample, and the result showed that although vegetable-based lubricants are compatible with humans, bacteria colony can quickly grow there without making any apparent changes that lead to harm to operators in a mysterious way. In the present work, the hypothesis of the safety of unreinforced vegetable-based lubricants has been rejected, and a new window on the environmental issues of vegetable-based lubricants has been presented. In the final, to eliminate environment-human risks and to reduce consumption of lubricant and natural resources to green manufacturing, a comprehensive study on the possibility of completely removing lubricant was performed. The results showed that the machining without lubricant could be replaced with the traditional method.

Tribological tests of micro-arc oxidation coatings in environmentally safe lubricants

This study is devoted to wearing resistance of MAO-coatings formed on aluminum alloys 2024 (Al-Cu-Mg) and 7075 (Al-Zn-Mg-Cu) at the friction in pair with steel 100Cr6 in environmentally safe lubricants and represents a generalization and analysis of tests’ results. Investigations were conducted using two methods: reciprocating sliding on the “ball-on-disk” friction scheme and unidirectional sliding on the “pin-on-disk” friction scheme. As environmentally lubricants were used some base oils like polyalphaolefin (PAO), polyethylene glycol (PEG), Silicon Oil, perfluorinated polyether (PFPE) and diisotridecyl adipate ether (DITA). Tests on the first friction scheme allowed us to determine the maximal value of load for investigated friction pairs and tests on the second friction scheme showed their antifriction properties in different lubricants and in the mode of the greasing starvation. There was revealed that MAO-coatings formed on alloy 7075 at high contact pressures demonstrate a friction coefficient lower than on alloy 2024. Some problems of the used “pin-on-disk” scheme is discussed also for improving the tests’ results data.

Pre-cooling Intensity Effects on Cooling Efficiency in Cryogenic Turning

The requirement for utilization of safe lubricants is rising in all parts of the industry due to human and environmental concerns. Therefore, complete omission or replacement of the mineral-based cutting fluids by safer ones is deemed to be very important in today’s machining operations. In the present study, the effect of pre-cooling in cryogenic machining using liquid nitrogen was compared with dry machining. Tool temperature, workpiece surface quality and tool wear were studied as the output response parameters. The results showed that the tool temperature had no sensitivity to the cutting parameters when liquid nitrogen was employed. However, in dry machining as the cutting parameters (i.e., cutting speed and feed rate) increased, the cutting temperature rose. Pre-cooling by liquid nitrogen led to reduction of the tool temperature by 73–86% compared with the dry method. Also, surface quality in terms of defective zones such as adhered materials, removed regions, and scratch marks was evaluated. It was observed that many defects were formed on the workpiece surface in dry machining, whereas it was completely defect free in cryogenic machining. Concerning the tool wear, the SEM images of tool rake face showed that the tool wear under the mechanisms of adhesion and breakage was observed in a vast area of the tool surface in dry machining, enhancing the creation of defects on the workpiece surface.

Tribological Features of Environmentally Safe Lubricant Compositions Based on Rapeseed Oil

Tribological Features of Environmentally Safe Lubricant Compositions Based on Rapeseed Oil

Effect of a Natural Eye Drop, Made of Plantago Ovata Mucilage on Improvement of Dry Eye Symptoms: A Randomized, Double-blind Clinical Trial.

Dry eye disease is a relatively common eye disorder associated with decrease in quality of life. In this study, efficacy of an eye drop of Plantago ovata mucilage on symptoms of dry eye disease was evaluated. In a randomized, double-blind, placebo-controlled clinical trial, sixty dry eye patients with ocular symptoms and total Ocular Surface Disease Index (OSDI) score of ≥12 were randomly assigned to receive either a natural ophthalmic drop, made of Plantago ovata mucilage or placebo 4 times a day for 6 weeks. The patients were evaluated at pretreatment (baseline), weeks 4 and 6 post-treatment. The evaluation of the efficacy and safety were conducted based on the OSDI questionnaire, the noninvasive tear film break-up time (NI-BUT) with keratograph, the Schirmer test without anesthesia, and the osmolarity test, as well as by monitoring possible adverse events. After 6 weeks, within group analysis showed a significant improvement in total OSDI score (p < 0.001). In addition, between group comparison revealed a significant improvement in the OSDI score of the intervention group (p < 0.001). Although, NI-BUT was significantly improved in the Plantago ovata group (p = 0.004), however no statistically significant difference was observed in between group analysis. There were no significant differences between two groups, or significant changes within the groups in the Schirmer test without anesthesia and the osmolarity test. No serious adverse events were reported. In conclusion, P. ovata mucilage is a natural, inexpensiveness, and safe lubricant polymer that could have beneficial ocular effects on subjective symptoms of the patients with dry eye disease.

Development of Environmentally Safe Lubricants Modified by Grapheme

A technique of lubricant modification using graphene is presented. The experimental results of the determination of the tribological characteristics inherent in the modified lubricant show that, when 0.1% of multilayered graphene is added to the complex calcium lubricant, the diameter of the wear spot exhibits a 50% decrease, the scuffing index shows a 2.9-fold increase, and the carrying capacity increases 3.8 times.

Condom Carnival: feasibility of a novel group intervention for decreasing sexual risk

Young people who engage in unprotected sex are at risk of negative consequences. The current study explored pre-post assessment data from 124, mostly Black, young people (M age = 19.6, SD = 2.8) attending an educational and vocational training programme who participated in the Condom Carnival, a novel, brief, interactive, peer-led, culturally tailored, sexual risk reduction group intervention. Condom Carnival activities provided practice negotiating condom use and using condoms correctly, instruction on safe lubricant use, and opportunities to dispel myths regarding condom size and breakage. We examined the preliminary impact of the Condom Carnival in increasing participants’ condom-related self-efficacy, lubricant safety awareness, and condom-related behavioural intentions and behaviour likelihood. Despite previous exposure to prevention efforts, participants reported significant increases in lubricant safety awareness (p < 0.001) and intentions to carry a condom in the next year (Z = −2.05, p = 0.04). Although participants reported high condom-related self-efficacy and intentions to use a condom, only three-quarters of young people endorsed intentions to always carry a condom. Findings indicate the need to explore the gap between intentions to use and carry condoms and to develop effective strategies to increase condom carrying among young people. Further assessment of the Condom Carnival as an add-on intervention to enhance sexual risk reduction efforts among youth is warranted.

A New Tribological Approach for Lubricated Sliding Contact of Pitted Metallic Curvature Cup

ABSTRACTInterest in the development and application of plant-based lubricants for medical use is increasing. This study investigates palm oil lubricants as environmentally friendly and renewable resources to optimize the motion in an ergonomic simulated metal hip prosthesis with modification to the acetabular cup surface. Although metal hip replacements are extensively used, minimizing metal-on-metal friction and wear using safe lubricants requires further investigation. The main physical properties of palm kernel oil and palm fatty acid distillate are considered. The viscosity, wear scar, and coefficient of friction are compared to hyaluronic acid. A modified pin-on-disc tribometer simulates friction and wear on a 28-mm-diameter acetabular cup and microscopy image analysis is used to examine the wear scar. The physical properties of palm oil derivatives reduce friction and wear. In brief, the most significant results of this study include the effect of lubricant and number of pits on wear and friction coefficient. The contribution of this research work is to maintain stability and increase the lifetime of ergonomic metal hip implants.

Men who have sex with men in Kisumu, Kenya: support group membership and knowledge of HIV-risk factors

Men who have sex with men are an important yet marginalised population for HIV prevention in Africa. We conducted a two-phase study (individual qualitative interviews and a survey) of men who have sex with men, aged 18–34 years of age and living in Kisumu, Kenya. Approximately half (27/51) of survey respondents reported belonging to a support group. The odds of belonging to support groups were greater for older men (aged 24–34 versus 18–23 years [OR = 5.20; 95%CI = 1.27–26.66]). More than two-thirds (68.6%) of survey respondents were categorised as having high knowledge of HIV-risk factors. Most respondents (94.1%) correctly reported lack of condom use during vaginal sex as a risk factor for HIV, but slightly fewer (82.4%) recognised lack of condom use during anal sex as an HIV risk factor. Among the 15 interviewees, the following were included as greatest needs: health information (n = 5), safe lubricants (n = 5), condoms (n = 4), healthcare facility or men-who-have-sex-with-men-friendly health services (n = 3) and advocacy (n = 2). Kenyan men who have sex with men have developed support groups and have unmet needs for information, lubricants and condoms and services. Partnering with support groups offers an opportunity for organisations to reach men who have sex with men with accurate health information, provision of safe sexual lubricants, condoms and other health and social services.

Eco‐friendly base fluids for lubricant oil formulations

AbstractThere is an increasing move towards the use of environmentally safe lubricants. However, the development of a common biodegradable base stock that could replace conventional ones is a big challenge. Synthetic lubricants, whether synthetic hydrocarbons, organic esters, or others, all have problems associated with their use. However, in general terms synthetic lubricants protect better, last longer, and outperform their conventional mineral‐based counterparts in certain applications. Future lubricant specifications in view of the demand for improved performance to meet stringent environmental regulations are the main drivers for new technological developments. As part of a study to produce polyol ester lubricant base stocks from C5 polyols and C6‐C14 carboxylic acids in the presence of eco‐friendly catalysts, a series of products has been synthesised. A biodegradable lubricant formulation for automotive transmission fluids has been developed based on a synthesised product as a base fluid. This paper reports on the physico‐chemical characteristics and performance evaluation results of this formulation, which is a promising base stock for automotive transmission fluids.