Polyol Ester Research Articles

Influence of ZnO nanoparticles on thermophysical and tribological properties of polyolester oil

An experimental assessment of thermo-physical, tribological, and eco-friendly properties of polyolester (POE) oil with zinc oxide (ZnO) nanoparticles for use as nanolubricant in refrigeration compressor. The ZnO nanolubricants were added in the mass fractions in the range from 0.1% to 0.5%, at the temperatures of 0 °C, 20 °C, 30 °C, 40 °C, and 60 °C. The thermophysical properties include thermal conductivity, kinematic viscosity, flash point, fire point, pour point, and cloud point with respect to various proportions. The morphology and size of ZnO nanoparticles are studied using the scanning electron microscope test. The tests findings suggest that ZnO nanoparticles greatly improved the friction characteristics of pure POE oil. The addition of the concentration decreases the pour point by 13.6%; at the same time, the flashpoint is improved by 3.5% when the POE oil is blended with ZnO. Zinc oxide nanoparticles could improve the refrigerants’ performance by extending life and avoiding friction problems. The optimum ZnO content of nanolubricants is, therefore, 0.3% for the POE/ZnO nanoparticles addition. The COF values are reduced by 6.95% at the optimum concentration over that with POE oil. The nanoparticles’ addition up to 0.3% results in less wear as they provide a defensive film between the surfaces during their motion. The mass loss value increased due to the aggregation of ZnO nanoparticles. The higher thermal conductivity is obtained for the 0.3% volume fraction of nanoparticles, and other 0.1% and 0.5% volume fractions lesser.

Borate esters of polyols: Occurrence, applications and implications

Boric acid (or inorganic borate) and polyols with vicinal hydroxyl groups are starting materials for the synthesis of borate esters. Boron biomolecules are examples of this type of borate esters, which are associated with metabolism of plants and bacteria. These biological compounds could have inspired the use of inorganic boron reagents to mimic a few prebiological syntheses and to prepare new compounds for different purposes, e.g., in medicine and agriculture; this means that these groups of borate esters are related to several applications and have significant scientific implications. This will be discussed for borate esters synthesized in aqueous media, including as hydrogels, as well as their potential usages, taking into account advantages and limitations of boric acid (or inorganic borate) chemistry. Additionally, these inorganic boron species will be compared with boronic acids, as well as their esters.

Experimental investigation for the solubilities of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) in polyol ester, polyvinylether, and polyalkylene glycol base oils

• Dimensional synthesis compared four-, six- and eight-bar mechanism gait trainers. • Eight-bar configuration had greater kinematic accuracy with constant input velocity. • Kinematic accuracy was similar for all mechanisms with well-controlled input. Knowledge of the solubility of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) in lubricant oil is an indispensable factor for designing refrigeration system and choosing suitable lubricant oil. In this work, the solubilities of R1234yf in polyol ester (POE) base oil, polyvinylether (PVE) base oil, and polyalkylene glycol (PAG) base oil were measured in the temperatures range from 273 K to 353 K based on the isochoric method. The experimental solubility data were correlated using the Peng-Robinson (PR) equation of state and Wilson activity coefficient model. The absolute average relative deviations of the experimental data and calculated values for the R1234yf + POE base oil system, R1234yf + PVE base oil system, and the R1234yf + PAG base oil system are 2.47%, 1.66%, and 1.29%, respectively.

Silica-Supported Fe(II), Co(II) and Ni(II) Complexes as Efficient Catalysts to Esterification of Levulinic acid with Polyol

Biomass-derived feedstocks were used to synthesize a new polyol-based ester for biolubricant production to overcome the dependence on mineral oil. Although biomass-derived oil is a potential alternative to polyol ester, upgrading is inevitable before using it as a biolubricant. Levulinic acid (model acid), obtained from a bio oil, was used for the esterification of two polyols, for example, neopentyl glycol (NPG) and trimethylolpropane (TMP), in the presence of ligand metal Fe(II), Co(II), and Ni(II) complexes as catalyst. Silica-supported Fe(II), Co(II) and Ni(II) complexes viz. [Fe(Tyr)(Amp)]Cl·SiO2, [Co(Phe)(Bpy)]Cl·SiO2 and [Ni(Leu)(Phen)]Cl·SiO2 were synthesized by the reaction of ligands [L-phenylalanine (Phe), L-tyrosine (Tyr), L-leucine (Leu), 4,4′-bipyridine (Bpy), 2-aminopyridine (Amp) and 1,10-phenanthroline (Phen)] with respective metal(II) chloride salts. All the metal complexes were characterized by elemental analysis, magnetic susceptibility, TGA/DTA, FTIR, powder-XRD and SEM methods. The catalytic activities of the complexes were further investigated via esterification of two polyols (e.g. neopentyl glycol and trimethylolpropane) by biomass-derived levulinic acid (LA). Herein, iron(II) complex was found to be more active, demonstrating its better efficiency as a catalyst towards the esterification of levulinic acid for synthesizing ester-based oils.

Genomics- and Metabolomics-Based Investigation of the Deep-Sea Sediment-Derived Yeast, Rhodotorula mucilaginosa 50-3-19/20B.

Red yeasts of the genus Rhodotorula are of great interest to the biotechnological industry due to their ability to produce valuable natural products, such as lipids and carotenoids with potential applications as surfactants, food additives, and pharmaceuticals. Herein, we explored the biosynthetic potential of R. mucilaginosa 50-3-19/20B collected from the Mid-Atlantic Ridge using modern genomics and untargeted metabolomics tools. R. mucilaginosa 50-3-19/20B exhibited anticancer activity when grown on PDA medium, while antimicrobial activity was observed when cultured on WSP-30 medium. Applying the bioactive molecular networking approach, the anticancer activity was linked to glycolipids, namely polyol esters of fatty acid (PEFA) derivatives. We purified four PEFAs (1–4) and the known methyl-2-hydroxy-3-(1H-indol-2-yl)propanoate (5). Their structures were deduced from NMR and HR-MS/MS spectra, but 1–5 showed no anticancer activity in their pure form. Illumina-based genome sequencing, de novo assembly and standard biosynthetic gene cluster (BGC) analyses were used to illustrate key components of the PEFA biosynthetic pathway. The fatty acid producing BGC3 was identified to be capable of producing precursors of PEFAs. Some Rhodotorula strains are able to convert inulin into high-yielding PEFA and cell lipid using a native exo-inulinase enzyme. The genomic locus for an exo-inulinase enzyme (g1629.t1), which plays an instrumental role in the PEFA production via the mannitol biosynthesis pathway, was identified. This is the first untargeted metabolomics study on R. mucilaginosa providing new genomic insights into PEFA biosynthesis.

Experimental Investigation for Solubility of Weak Flammable trans-1,3,3,3-Tetrafluoropropene (R1234ze(E)) in PVE and POE Lubricants

R1234ze(E) is one of the new generations of refrigerants that are environment-friendly. The solubility of R1234ze(E) in the polyvinyl ether (PVE) 32 and polyol ester (POE) 32 oils was measured at a...

Surface functionalisation of poly-APO-b-polyol ester cross-linked copolymers as core\u2013shell nanoparticles for targeted breast cancer therapy

Polymeric nanoparticles (NPs) are commonly used as nanocarriers for drug delivery, whereby their sizes can be altered for a more efficient delivery of therapeutic active agents with better efficacy. In this work, cross-linked copolymers acted as core–shell NPs from acrylated palm olein (APO) with polyol ester were synthesized via gamma radiation-induced reversible addition-fragmentation chain transfer (RAFT) polymerisation. The particle diameter of the copolymerised poly(APO-b-polyol ester) core–shell NPs was found to be less than 300 nm, have a low molecular weight (MW) of around 24 kDa, and showed a controlled MW distribution of a narrow polydispersity index (PDI) of 1.01. These properties were particularly crucial for further use in designing targeted NPs, with inclusion of peptide for the targeted delivery of paclitaxel. Moreover, the characterisation of the synthesised NPs using Fourier Transform-Infrared (FTIR) and Neutron Magnetic Resonance (NMR) analyses confirmed the possession of biodegradable hydrolysed ester in its chemical structures. Therefore, it can be concluded that the synthesised NPs produced may potentially contribute to better development of a nano-structured drug delivery system for breast cancer therapy.

The Effects of Triton X-100 and Tween 80 Surfactants on the Thermal Performance of a Nano-Lubricant: An Experimental Study

In this experimental study, experiments were carried out using a nano-lubricant consisting of polyol ester (POE)—titanium dioxide (TiO2)—surfactant instead of POE oil used in the compressor in a refrigeration system cycle test apparatus. The main aim of the study was to provide more efficient operation of the refrigeration system. Triton X100 (TX-100) and sorbitan polyoxyethylene monooleate (Tween 80) were used as the surface-active material. Nano-lubricants were formed by mixing TiO2 nanoparticles with POE oil at different concentrations. At these different nanoparticle concentrations, 0.5% of the surfactant was used. The reason for using a surfactant in the nano-lubricant was to prevent agglomeration in the mixture. TX-100 and Tween 80 surfactants were also used to study the effects of the surfactant on the nano-lubricant. Experiments were carried out using three different concentrations and three measurements for each concentration using the POE/TiO2/surfactant nano-lubricants. The best improvement was achieved when a nano-lubricant consisting of a mixture of TX-100 and POE oil with a concentration of 1.5% TiO2 was used. The improvement in coefficient of performance (COP) for the refrigeration cycle was 39.42%.

Characterization, coating and biological evaluation of polyol esters rosin derivatives as coating films

Polyol esters materials, which have been developed from ethylene glycol, glycerol, pentaerythritol and sorbitol with rosin, were investigated for their formed films and coating properties. Films were dried and characterized for chemical and mechanical resistances. Their films were highly resistant to water, solvents (acetone, toluene and methanol), and acids (10% hydrochloric acid and 20% sulfuric acid) and poorly resistant to alkali (10% sodium hydroxide) as well as adhesion, tensile strength, elongation test, modulus of elasticity, pinhole test and scratching and flexibility tests. Incorporation of ethylene glycol, glycerol, pentaerythritol and sorbitol with rosin was done to achieve good mechanical characteristics and high chemical resistance to these films. The prepared compounds were tested for antibacterial activity against Trametes versicolor and Gloeophyllum trabeum.

Experimental investigation of Sio2 nanolubricants for R410A vapour compression refrigeration system

Abstract In this paper Sio2 nanoparticles is dispersed in lubricating oil of R410A refrigeration system. Experimental investigation was carried using 0 g/L, 0.2 g/L, 0.4 g/L and 0.6 g/L of Silicon dioxide (Sio2) nano particle concentrations in Polyolester (POE) lubricating oil by varying the mass of refrigerant R410A as 30, 40, 50, 60 and 70 g. The performance of the refrigeration system was investigated using the important parameters like Coefficient of performance, refrigerating effect and compressor work and pull down test. From the experiment it has been concluded that 0.4 g/L Sio2 nano-lubricant and 40 g refrigerant mass gave more refrigerating effect and it was found to be 160 W when compared with system without nanolubricants and with 0.2 g/L and 0.6 g/L nanolubricant with various refrigerant mass charges. Addition of Sio2 nanolubricants results in reduced compressor work of 80 W with 0.4 g/L and 40 g of refrigerant. Dispersion of Sio2 nanolubricants leads to enhanced C.O.P value of 1.7 for 0.4 g/L nanolubricants when compared to system without nanolubricants and with 0 g/L, 0.2 g/L and 0.6 g/L nanolubricants. From the pull down test, the obtained evaporator temperature is reduced very quickly while using 0.4 g/L nanolubricants with 40 and 60 g refrigerant mass charges.

The Performance Simulation of The New R463A HFC/HFO/Carbon Dioxide Refrigerant with Lower GWP, As an Alternate Option for The R404A Refrigeration System

This study presents the performance simulation of the R463A that has been developed to be retrofitted to replace the R404A. The R463A is primarily composed of hydrofluorocarbons/hydrocarbon/carbon dioxide (HFCs/HCs/CO2). The R463A refrigerant (GWP=1494) is a non azeotropic mixture of R32 (36%), R125 (30%), R134a (14%), R1234yf (14%), and R744 (6%). It is composed of polyol ester oil (POE), and classified as a Class A1 incombustible and non-toxic refrigerant. The R463A has a higher cooling capacity (Qe) than the R404A, as it is composed of hydrofluorocarbons (HFCs) R32 and carbon dioxide (CO2) R744, and also has a lower global warming potential (GWP) than the R404A due to the hydrofluoroolefins (HFOs) by R1234yf. The properties of the R463A and R404A that uses the REFPROP and CYCLE_D-HX software, is in accordance to the CAN/ANSI/AHRI540 standard air-conditioning, heating, and refrigeration institute (AHRI). The normal boiling point of the R463A was found to be higher than the R404A by 23%, with a higher cooling capacity and a lower GWP value by 63% than the R404A. The critical pressure and temperature of the R463A was found to be higher than the R404A, i.e. it can be used in a high ambient temperature environment, and emits a higher refrigerant effect and heat reject with a lower global warming potential (GWP) than the R404A by 52%, due to its hydrofluoroolefins (HFOs) by R1234yf component. The COP of the R463A was found to be higher than the R404A by 10% under low temperature application.

Enzymatic Synthesis of a Polyol Ester from Levulinic Acid and Trimethylolpropane and Its Tribological Behavior as Potential Biolubricant Basestock.

In this study, a polyol ester from levulinic acid (LA) and trimethylolpropane (TMP) was synthesized by enzymatic catalysis in a solvent-free system. The total conversion of TMP reached up to 84% on average after lipase recycling for five times. The produced ester showed excellent lubrication properties, such as high viscosities at 40 °C (86.53 mm2/s) and 100 °C (8.91 mm2/s), a good viscosity index (49), a low pour point (−27 °C), and a high flash point (223 °C). The frictional wear behavior was evaluated on a four-ball test machine (FTM) by adding the ester into a reference mineral oil. The blend with 10% ester showed a smaller wear scar diameter (WSD) (0.62 mm) when compared with that of pure mineral oil (0.78 mm). The results demonstrated that the obtained ester has huge potential as biolubricant basestock.

Environmentally friendly processes from coffee wastes to trimethylolpropane esters to be considered biolubricants

ABSTRACT In this study, an eco-friendly renewable biodegradable alternative to petroleum-based oil lubricants was produced using espresso coffee wastes. Waste coffee oil used as raw material was extracted from Espresso coffee wastes by Soxhlet and conventional solvent extraction. Free fatty acids (FFA) were obtained by hydrolysis of the obtained waste oil using Lipozyme TL IM (Thermomyces lanuginosus). The byproduct, glycerol, was also separated from the reaction medium using a separatory funnel. The obtained FFA was used as a raw material in the production of TMP esters. Polyol esters of fatty acids were synthesized as a result of the esterification reaction between FFA and polyol alcohol (trimethylolpropane (TMP)) using Novozyme 435 (Candida antarctica). The amount of FFA in the medium and the FFA conversion was determined by titration with NaOH solution according to ASTM D 5555–95 standard and the FFA composition of espresso coffee oil by GC. The oil content of espresso coffee extract was found to be rich by 16% and the FFA composition was rich in palmitic acid (C16:0 43% by weight) and linoleic acid (C18:2 31% by weight). 31% of FFA was obtained from the coffee oil. Experimental studies have shown that the highest FFA conversion of 88% with 93% TMP tri-ester content was obtained at a temperature of 55°C, 5% enzyme (w/w), non-aqueous media, 3/1 FFA/TMP mole ratio, 500 rpm mixing speed and 24 hours. Implications: Filter coffee wastes, which have become one of the most important biological wastes with an annual production capacity of 6 million tons worldwide; It is targeted to be transformed into environmentally friendly products, as it is important in terms of economy and policies of many developing countries, it is a renewable resource and there is a high amount of waste accumulation day by day. Evaluation of waste filter coffees and oils with this research article; It is envisaged that the bio-lubricating oil used in many sectors will be synthesized and commercialized with an environmentally friendly process.

The Replacement of the R404A Refrigeration System with The Environmentally Friendly R448A, to Improve Convenience Store Energy Efficiency in Thailand

This study presents the energy saving characteristics of the R448A, instead of the R404A refrigeration system, in 5 convenience stores, with a total of 150 m2, situated in Central Thailand. The R448A hydrofluorocarbons/hydrofluoroolefins (HFCs/HFOs) (GWP=1390) is a non-azeotropic mixture of R32 (26%), R125 (26%), R1234yf (20%), R134a (21%) and R1234ze (E) (7%), which can be retrofitted to replace the R404A refrigeration system. The R404A hydrofluorocarbons (HFCs) (GWP=3735) is a near azeotropic mixture of R125 (44%), R143A (52%), R134A (4%). Both refrigerants are composed of polyol ester oil (POE), are incombustible and non-toxic. The R448A has a higher cooling capacity (Qe) and lower global warming potentials (GWP) than the R404A due to its hydrofluorocarbons (HFCs) R32 component and hydrofluoroolefins (HFOs) R1234yf/R1234ze (E) component, as opposed to the R404A. This was determined by measuring power consumption (kWh) and the ambient temperature (°C) through the use of power meters and temperature data logger respectively. The result obtained was able to summarize the relationship of all the parameters concerned, and showed an energy-saving average of 7.9%, i.e. 28,273 kWh/year per 5 stores, and a decreased global warming potential (GWP) of 70%, through the use of a digital scroll compressor.

Measurements and Correlations of the Thermal Conductivity of Three Polyol Esters and a Polyol Ester-Based Lubricant

This work describes measurements of the thermal conductivity of three polyol esters pentaerythritol tetrapentanoate (POE5), pentaerythritol tetraheptanoate (POE7), pentaerythritol tetranonanoate (POE9), and a fully qualified lubricant meeting military specification MIL-PRF-23699 with a transient hot-wire method. Correlations for the thermal conductivity based on the measurements are also provided. The expanded relative uncertainty of the measurements with a coverage factor of k = 2, approximately a 95 % confidence interval, is mostly 0.5 %.

Influence of structural factors on the tribological performance of organic friction modifiers

The influence of structural factors on the lubrication performance of organic friction modifiers (OFMs) formulated in Group V (polyol ester oil) base oil was studied using a ball-on-disk tribometer. The results show that OFMs can mitigate friction under heavy loads, low sliding speeds, and high temperatures. These conditions are commonly encountered in internal-combustion engines between cylinder liners and piston rings. The reduction in friction is ascribed to the boundary lubrication film containing the OFM. The chemical composition analysis of the metal disk surface using energy dispersive X-ray spectroscopy (EDS) confirmed the presence of a protective film of OFM on the wear track, albeit inconsistently deposited. Although the adsorption of the OFM on the metal surface was observed to be dependent on the chemical reactivity of the functional groups, levels of unsaturation, and hydrocarbon chain length of the OFM, the frictional performance was not always directly correlated with the surface coverage and tribofilm thickness. This implies that the friction reduction mechanism can involve other localized processes at the interface between the metal surface and lubricant oil. The occasional variation in friction observed for these OFMs can be attributed to the stability and durability of the boundary film formed during the rubbing phase.

Development and study of new lubricating compositions based on compound esters of cyclic polyatomic alcohols and industrial pentaerithritol ester

The simple and anisometric esters of 2.2.5.5-tetra methylol cyclopenthanole were synthesized with hexanole and heptanoic acids adding these esters to those of pentaerithritol and the mixture of fatty acids of С5-С9 fractions, oil compositions were prepared and studied as well. It was defined that operation characteristics of these compositions are significantly better than those of pentaerithritol ester and B-3W oil based on pentaerithritol ester. According to this data, the compositions based on polyol ester are recommended as new lubricants meeting modern standards.

Friction Characteristics and Mechanisms of Two Lithium Greases in Elastohydrodynamic Lubrication

Two types of lithium greases were fabricated by using PAO and polyol ester as two base oils. The friction tests for the lithium soap-based greases were performed under different operating conditions by mini-traction machine, and the data were compared and analysed. The results show that when the lithium-based soap thickens different types of base oils with the same viscosity, the greater the elastohydrodynamic friction coefficient of the base oil, the greater the elastohydrodynamic friction coefficient of the grease. In a low-speed bearing or contact pair, both base oil and thickener go through the contact zone to contribute to the friction of the grease. When the same lithium-based thickener thickens the different base oils, the greater the interactions between the base oil molecules, the greater the interactions between the base oil molecules and the thickener molecules, the wider the soap fibres, and the greater the friction coefficient of the grease. The friction coefficient of oil PAO–lithium-based soap grease is higher than that of its base oil PAO. The friction coefficient of oil polyol ester–lithium-based soap grease is less than that of its base oil polyol ester when the viscosities of the two base oils are 68 mm2/s.

Tribological properties of polyol ester – commercial motorbike engine oil blends

This current study investigates the effect of blending bio-lubricant with commercial lubricant on physico-chemical and tribological properties. The synthesis of TMP and PE ester are optimized to obtain 100% long chain tetra-esters and extreme care was taken during preparation of bio-lubricant to lessen deterioration of physio-chemical properties by blending with commercial oil. SM grade commercial petrol engine oil was blended with Tri-methylolpropane (TMP) ester, Penta-erythritol (PE) ester derived from Calophyllum-inophyllum in 10, 15, 20 and 25% v/v. The tests for anti-wear, anti-friction and extreme pressure properties are conducted on the sample oils on a four-ball wear tester. The friction coefficient and wear of bio-lubricant – commercial oil blends have decreased significantly up to 20% blending percentage. In the extreme pressure test, there is a substantial improvement in the weld load and marked improvement in the load wear index signifying the better load-bearing capacity of commercial oil – bio-lubricant blends. A synergy between bio-lubricant and additives in the commercial oil was found from a metallographic examination of worn balls after the EP test. The optimum volume percent of blend was found to be 15% PE blend and 10% TMP blend for optimum overall performance.

Density and viscosity of a polyol ester lubricant: Measurement and molecular dynamics simulation.

Polyol ester (POE) is the main component of many refrigeration lubricants. In this work, the density and the viscosity of a typical, pure polyol ester, pentaerythritol tetrahexanoate (PEC6), were measured over 258.15 K to 373.15 K and predicted with molecular dynamics simulations. Nonequilibrium molecular dynamics (NEMD) was employed to compute the shear viscosities for different shear rates. The Eyring model was used to fit the shear viscosities and to extrapolate to the Newtonian viscosity. A protocol was proposed to perform a NEMD-Eyring fit for a low-error, reproducible and robust Newtonian viscosity calculation. Three force fields, i.e., OPLS, LOPLS, and DREIDING, were tested in terms of their density and viscosity prediction accuracy. OPLS gave the best density prediction (within ± 0.2 %), while LOPLS showed the best viscosity prediction accuracy (within - 4 % to 20 %). This work illustrates the value of molecular simulation in predicting lubricant properties and its potential in guiding the design of POE lubricants for desired properties.