Natural Ester Research Articles

Karakteristik Breakdown Voltage Pada Dielektrik Minyak Mineral dan Minyak Ester Natural

The increasing demand for electrical energy, driven by population growth and industrial development, necessitates efficient and sustainable power distribution systems. Transformers, essential components of these systems, typically use mineral oil for insulation and cooling, despite its environmental drawbacks, such as high carbon emissions and non-biodegradability. In response, natural ester oils have emerged as eco-friendly alternatives. This study aimed to compare the dielectric breakdown voltage characteristics of mineral oil (Diala B) and natural ester oil (FR3) in transformer applications. The testing followed the IEC 60156 standard, focusing on transformers operating at 20 kV, with a minimum breakdown voltage threshold of 30 kV/2.5mm. Both treated and untreated samples were examined.The results indicated that FR3 ester oil exhibited superior dielectric properties, including higher breakdown voltage, flashpoint, and firepoint, as well as lower carbon emissions compared to mineral oil. These findings suggest that natural ester oil has significant potential as a sustainable replacement for mineral oil, particularly in applications where environmental and safety concerns are prioritized.The study recommends further long-term testing under operational conditions to confirm the performance and stability of ester oil in real-world transformer applications. These findings contribute to the growing body of research supporting the transition to more environmentally friendly transformer insulation materials, which could have broad implications for the power industry’s sustainability efforts

New insights on thermal ageing of electrical insulating oils as revealed from photoluminescence and absorption spectroscopy

AbstractRecently, significant efforts have been exerted to replace mineral oil with environmentally friendly oils due to safety and environmental issues. However, there is a need to clarify the physical mechanisms behind the ageing impact of these oils. The authors use advanced optical spectroscopy techniques in correlation with dielectric measurements to understand the ageing processes in environmentally friendly oils as well as mineral oil. Firstly, different samples of environmentally friendly oils and mineral oil were utilised to investigate the ageing mechanism. The samples were subjected to different ageing periods using a thermal accelerated ageing process. Secondly, the severity of the produced byproducts due to the oil degradation is examined based on several measured properties representing macroscopic and microscopic categories. The macroscopic category was evaluated through dielectric properties, including breakdown voltage, dielectric permittivity, and dissipation factor. The microscopic category, on the other hand, was assessed using techniques such as ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopy. These techniques enabled a deep understanding of the molecular‐level changes occurring in the oil under ageing conditions, thereby getting new insights into oil ageing mechanisms. It is worth mentioning that natural ester oil demonstrated the most favourable performance across various properties under ageing conditions.

Design, Synthesis, Molecular Docking, and in vitro Cytotoxicity Studies of Marine Natural Product Herdmanine Derivatives as Multitarget Inhibitor for EGFR and HER2 Breast Cancer Proteins

AbstractBreast cancer is a potentially deadly disease that affects millions of individuals worldwide. Therefore, it is crucial to design highly targeted therapeutic techniques with low toxicity. In this work, we synthesized natural product Herdmanine's ester derivatives and tested them against EGFR and HER2 proteins as multitargated inhibitor of breast cancer progression. Further, the newly synthesized compounds were evaluated for cytotoxicity against breast cancer cell lines MCF‐7, MDA‐MB‐231 and MDA‐MB‐157 and the biocompatibility towards NIH 3T3 cells. Higher toxicity and positive viability profiles of Herdmanine derivatives indicate their potential use for further exploration in breast cancer application.

Advancing Thermal Stability in Natural Ester Oil-Paper Insulation Systems via Precision Nanostructuring with Parylene Films: Experimental and Molecular-Level Comprehensive Assessment

The oil-paper insulation system in eco-friendly fire-retardant transformers depends on hydrophilic natural ester insulating oil. Moisture within the system synergistically interacts with aging, worsening oil-paper insulation degradation and hastening overall system aging. Chemical vapor deposition was used to create parylene surface-modified insulating paper as a strategy to inhibit moisture-induced aging in natural ester oil-paper insulation. The effectiveness of the approach was identified by a comprehensive assessment of the physicochemical and electrical properties of the parylene surface-modified insulating paper. The findings from accelerated thermal aging at 130 °C for 90 days on the natural ester oil-paper insulation system reveal the outstanding lipophilic and hydrophobic properties while maintaining electrical characteristics of the parylene surface-modified insulating paper. After 90 days of aging, the parylene surface-modified insulating paper exhibited a 56.76% higher degree of polymerization and a 19.36% significantly lower moisture content than conventional cellulose insulating paper. In the natural ester oil-paper insulation system, the parylene surface-modified insulating paper led to a notable 63% reduction in insulating oil acid value, a 60.50% decrease in dielectric loss, and a substantial 20.35% increase in AC breakdown voltage. Molecular-level investigations revealed the inhibitory mechanism of the parylene film, offering a promising solution to enhance the thermal stability and aging resistance of natural ester oil-paper insulation systems.

Analysis of impulse withstand voltage of ester-based nanofluids

Ester-based nanofluids constitute an effective ecological alternative to petroleum-derived dielectric fluids for electrical engineering industry. Pulse induced dielectric breakdown is a key cause of power device failure. In this paper, we deal with the lightning impulse breakdown voltage (LI BDV) in natural and synthetic ester-based (NE and SE) nanofluids with various concentrations of magnetite (Fe3O4) and fullerene (C60) nanoparticles. The nanofluids show a decrement in positive polarity LI+ BDV as compared with the base ester. Negative polarity LI- BDV in the nanofluids is similar to that of base oils. Weibull statistical distributions are applied to analyse the results at different cumulative probabilities of 1 %, 10 %, and 50 %. Natural ester with C60 nanoparticles shows higher positive LI+ BDV values at a low probability level, while the negative LI- BDV reaches higher values at higher probability levels. The decreased LI BDV in NE and SE due to the magnetite nanoparticles are attributed to the nanoparticle clustering and percolation. The tendency of C60 nanoparticles to enhance the LI BDV in NE but not in SE is interpreted in the view of the nanoparticle concentration and oil's viscosity effect on the streamer branching and propagation.

An Exploratory Study of the Enzymatic Hydroxycinnamoylation of Sucrose and Its Derivatives.

Phenylpropanoid sucrose esters are a large and important group of natural substances with significant therapeutic potential. This work describes a pilot study of the enzymatic hydroxycinnamoylation of sucrose and its derivatives which was carried out with the aim of obtaining precursors of natural phenylpropanoid sucrose esters, e.g., vanicoside B. In addition to sucrose, some chemically prepared sucrose acetonides and substituted 3'-O-cinnamates were subjected to enzymatic transesterification with vinyl esters of coumaric, ferulic and 3,4,5-trimethoxycinnamic acid. Commercial enzyme preparations of Lipozyme TL IM lipase and Pentopan 500 BG exhibiting feruloyl esterase activity were tested as biocatalysts in these reactions. The substrate specificity of the used biocatalysts for the donor and acceptor as well as the regioselectivity of the reactions were evaluated and discussed. Surprisingly, Lipozyme TL IM catalyzed the cinnamoylation of sucrose derivatives more to the 1'-OH and 4'-OH positions than to the 6'-OH when the 3'-OH was free and the 6-OH was blocked by isopropylidene. In this case, Pentopan reacted comparably to 1'-OH and 6'-OH positions. If sucrose 3'-O-coumarate was used as an acceptor, in the case of feruloylation with Lipozyme in CH3CN, 6-O-ferulate was the main product (63%). Pentopan feruloylated sucrose 3'-O-coumarate comparably well at the 6-OH and 6'-OH positions (77%). When a proton-donor solvent was used, migration of the 3'-O-cinnamoyl group from fructose to the 2-OH position of glucose was observed. The enzyme hydroxycinnamoylations studied can shorten the targeted syntheses of various phenylpropanoid sucrose esters.

Development of biobased, sustainable and environmentally friendly glycerol ester rosins for the production of thermoplastic road marking paint

AbstractIn recent years, natural rosin derivatives have gained significant importance in the production of sustainable bio‐based materials, including thermoplastic road marking paint (TRMP). This study evaluates the use of sustainable natural glycerol ester rosins as bio‐based binders in TRMP formulations, specifically focusing on pine, wood, and tall oil rosins. Various analytical techniques, such as FT‐IR, TGA, MALDI‐TOF‐MS and GPC‐HPLC, were utilized to analyze both unmodified and glycerol ester rosins. Standard tests, including acid number (mg KOH/g) ASTM D 465‐05 and softening point (°C) ASTM E 28‐99, were also conducted on the samples. The optimum synthesis conditions for glycerol ester rosins (GER) were determined as follows: a rosin/glycerol molar ratio of 2.54, catalyst/rosin weight ratio of 0.5%, and antioxidant/rosin weight ratio of 1.0%. GPC‐HPLC analysis revealed average esterification reaction yields of over 90.85%. Furthermore, TRMPs underwent various tests, including gloss factor (β), chromaticity coordinates (x, y), UVB aging, and softening point (°C). The results demonstrated that GERs exhibited superior performance, especially in the UVB aging test, with all TRMPs classified as UV1 type. These findings highlight the promising potential of GERs derived from different types of rosins in producing sustainable, environmentally friendly, and bio‐based next‐generation TRMPs.

Synthetic Modification and Insecticidal Activity of 4-epi-cis-Dihydroagarofuran Derivatives.

To synthesize the fundamental framework of dihydroagarofuran, a novel strategy was devised for constructing the C-ring through a dearomatization reaction using 6-methoxy-1-tetralone as the initial substrate. Subsequently, the dihydroagarofuran skeleton was assembled via two consecutive Michael addition reactions. The conjugated diene and trans-dihydroagarofuran skeleton were modified. The insecticidal activities of 33 compounds against Mythimna separata were evaluated. Compounds 11-5 exhibited an LC50 value of 0.378 mg/mL. The activity exhibited a remarkable 29-fold increase compared to positive control Celangulin V, which was widely recognized as the most renowned natural dihydroagarofuran polyol ester insecticidal active compound. Docking experiments between synthetic compounds and target proteins revealed the shared binding sites with Celangulin V. Structure-activity relationship studies indicated that methyl groups at positions C4 and C10 significantly improved insecticidal activity, while ether groups with linear chains displayed enhanced activity; in particular, the allyl ether group demonstrated optimal efficacy. Furthermore, a three-dimensional quantitative structure-activity relationship model was established to investigate the correlation between the skeletal structure and activity. These research findings provide valuable insights for discovering and developing dihydroagarofuran-like compounds.

Structure-Activity Relationship Models to Predict Properties of the Dielectric Fluids for Transformer Insulation System.

Mineral oils and synthetic and natural esters are the predominant insulating liquids in electrical equipment. Structure-activity relationship models to predict the key properties of pure insulating liquids, including pulse breakdown strengths, AC breakdown voltages, dielectric constants, flash points, and kinematic viscosities, have been proposed for the first time. Dependence of the specific properties on the molecular structures has been illustrated quantitatively in terms of surface area, statistical total variance, and average deviation of positive and negative electrostatic potentials, as augmented by molecular weight, volume, and ovality. Moreover, the individual contribution of the functional groups to viscosity has been revealed by an additive approach. The predicted properties are in good agreement with the experimental data. The present theoretical work provides new insights on the development of novel dielectric fluids.

Mechanism and technological method of leaching metals from waste lithium-ion batteries by synergistic action of natural organic reductants and mechanochemical method

In this study, litchi peel powder (LPP) was selected as a natural organic reductant to study the mechanism of green leaching of valuable metals from spent lithium-ion batteries (LIBs) by ball milling. LPP and cathode material were co-ball-milled(CBM) with water and then leached, LPP-assisted ball milling reduces the agglomeration tendency of the particles and increases the dispersion. Premixing by CBM makes the LPP and the cathode material fully contracted and tightly fused, and the mechanical force provides the activation energy of the reaction to accelerate the leaching. The leaching rates of Li, Co, Mn and Ni were 99.21 wt%, 96.52 wt%, 98.21 wt% and 94.79 wt% when LPP was added at 0.15 g and only 0.2 mol/L H3Cit was used. Compared with direct leaching, the amount of organic acids was reduced by 86.67 %. The proanthocyanidins contained in the LPP are the key to act as a reducing agent, and proanthocyanidins are the products of the combination of anthocyanins and glycosides. The natural phenolic and ester components in LPP are hydrolyzed into phenolic acids (protocatechulic acid, salicylic acid) and flavonoids (catechins) under the action of H3Cit, which accelerates the dissolution of metal oxides. The mechanism of natural organic reductant in auxiliary ball milling and organic acid leaching was clarified, which provided a new idea for the selection of ball milling auxiliary materials and proposed a economic and environmental protection method to leach valuable metals from spent LIBs.

Dynamic Thermal Behavior of Natural Ester Liquid-Filled Transformer for Offshore Wind Turbine in Cold Climate

The current study presents a dynamic thermal model (DTM) which accounts for variation of liquid properties with temperature to predict the development of temperature pattern of the entire transformer for offshore wind application during energizing process. The DTM is benchmarked against dynamic heat run test which is applied on a natural ester filled transformer designed for offshore wind application. The transformer is equipped with fiber-optic sensors (FOS) to observe the temperature distribution of the winding and the liquid during heating up and cooling down processes. The investigations involve in-depth analysis of the thermal behavior of the winding and liquid at different locations to give physical interpretation of the dynamic thermal response of different transformer components during dynamic loading. The results are further validated with transient computational fluid dynamics (CFD) simulations. Eventually, the study gives guidelines and recommendations of dynamic loading of transformer filled with natural ester in cold climate.

The diffusion behavior of H3O+ in insulation systems composed of paper cellulose and modified natural ester insulating oil

The oil-paper insulation system will be affected by the synergistic effects of moisture and acids during long-term stable operation of the transformer. The moisture in the oil can be combined with the H+ionized from the acid molecules in the form of H3O+ by coordination, thus changing the proportion of acid distribution in the insulating oil and paper cellulose. Natural ester insulating oil, as a new development trend to replace mineral oil, can be significantly improved by adding nanoparticles to them. The diffusion behavior of H3O+ in paper cellulose and nano-SiO2-modified soybean oil-based natural ester insulating oil insulating system has been investigated using molecular dynamics in this article. The results indicate that the incorporation with nanoparticles is effective in mitigating the impact of temperature on the diffusion behavior of H3O+ in oil-paper insulation. Compared with the unmodified model, the nano-modified model results in a significant reduction in the concentration distribution of H3O+ in paper cellulose. The hydroxyl and ether bonds in paper cellulose will interact with H3O+ to generate hydrogen bonds and destroy its original hydrogen bonding network, while nanoparticles can inhibit diffusion by adsorbing H3O+ through hydroxyl oxygen atoms.

The influence of small molecule products on natural ester impregnated cellulose insulation paper under electric-thermal coupling field

Transformer oil-paper insulation materials are vulnerable to insulation failure due to the influence of voltage, high temperature, and other complex conditions. Additionally, during the operation of the transformer, the generation of harmful substances such as small molecule acids and water becomes a significant concern. In this study, we employed molecular simulation technology to investigate the effect of small molecule products on natural ester-impregnated cellulose insulation paper under electric-thermal coupling field. The results show that: under the action of electric-thermal coupling, the introduction of the electric field can weaken the molecular thermal motion to a certain extent, and the higher the temperature, the more pronounced the weakening effect of the electric field. When subjected to an electric-thermal coupling field, the mean square displacement of the cellulose molecular chains inside the models doped with water and formic acid increases compared to the oil-paper composite model, with an increase of 60.13 % and 98.25 %, respectively, at 700 K. The fraction of free volume in the model increases and the cohesive energy density decreases, the diffusion ability of molecules inside the model remains strong. The weakening effect of the electric field does not diminish the hydrolysis reaction between the small molecular products and the cellulose molecular chains. This leads to a decrease in model stability and ultimately to the breakdown of the insulation paper.

The influence of doping with different surface modified SiO2 nanoparticles on the dielectric properties of natural ester insulating oil

Nanoparticles are presently considered to be high-potential filler materials in insulation medium. Surface-modified nanoparticles can not only improve the compatibility between nanoparticles and insulation liquid but also enhance the dielectric properties. Herein, models of soybean oil-based natural ester insulation oil doped with two silane coupling agents (A151, KH550) modified SiO2 were established, respectively. Molecular dynamics and DFT first principles were applied to explore the effect of two nanoparticles on the dielectric properties of liquid-insulation medium. The results showed that two types of nanoparticles can restrict the diffusion of water molecules by forming hydrogen bonds, while the number of hydrogen bonds in KH550–SiO2 is one-third more than that in A151-SiO2, and the interaction energy is lower, demonstrating a stronger adsorption effect on water molecules. Moreover, surface electrostatic potential and frontier molecular orbitals showed that KH550–SiO2 have a higher adsorption on charged particles in natural ester insulation oil, which can further inhibit the development of streamer discharge in the liquid insulation medium, improve its dielectric property and delay the aging and deterioration of natural ester insulation oil. This study extends our knowledge into the influence of silane coupling agents modified SiO2 nanoparticles on the dielectric performance of liquid insulation materials from a microscopic perspective.

Liquid-solid interface diffusion behaviors of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper

Furfural as an ageing product of cellulose paper can be detected by the furfural content in the oil. With the construction of green power grid, more and more power equipment adopts environmentally friendly insulating fluids. The investigation of the diffusion behaviors of furfural at different oil-paper interfaces can provide a basis for fault detection in power transformers. The liquid-solid interface diffusion behaviors of furfural in natural ester-cellulose paper and mineral oil-cellulose paper insulating systems are investigated by molecular dynamics simulation in this paper. Results show that the range of center-of-mass movement distances of furfural in mineral oil-cellulose paper is about 5 times that of natural ester-cellulose paper. The main reason for this is that the long-chain macromolecules composing the natural ester undergo curling in the extended flow. As polar molecules, natural ester can attract furfural, which is also a polar molecule. And the electrostatic potential mapping interval of furfural is about 4.4 times that of mineral oil, but 1.1 times that of natural ester, with which it overlaps more. These hinder the diffusion of furfural molecules in the natural ester-cellulose paper liquid-solid interface. This research provides theoretical support for the diffusion of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper. It also provides useful guidance for fault detection in transformers using natural ester insulating fluids.

Impact of mineral oil on key properties of natural esters under corona discharges, thermal, and electrical breakdown

Impact of mineral oil on key properties of natural esters under corona discharges, thermal, and electrical breakdown

Thermal and reactive effects in nanofluid flow around a contracting cylinder under magnetic field influence

This study investigates the dynamic behavior of natural ester-based ferrous oxide (Fe3O4) nanofluid flow around an unsteady contracting cylinder under the influence of a magnetic field, heat generation, and homogeneous-heterogeneous reactions. The governing equations for the flow, heat transfer, and chemical reactions are solved numerically using appropriate mathematical models. The bvp4c built-in MATLAB package is applied to address the complexity of the problem. The effects of magnetic field, heat generation, and reactive chemistry on the flow field, temperature distribution, and species concentration profiles are analysed comprehensively. As part of the validation process, we validate the reliability of our findings by comparing them to established benchmarks. Motivated by the increasing interest in environmentally friendly and sustainable fluid mediums, natural esters are chosen as the base fluid due to their biodegradability, low toxicity, and excellent insulating properties. This research aims to provide valuable insights into optimizing processes involving nanofluid flow in magnetohydrodynamic systems with reactive heat generation, utilizing natural esters as a promising alternative to conventional fluids. Insights gained from this study offer potential applications in various engineering and industrial contexts, contributing to the advancement of eco-friendly technologies.

Synthesis and in Vitro Evaluation of CAPE Derivatives as Ferroptosis Inducers in Triple Negative Breast Cancer.

Herein, we describe the design, synthesis, and in vitro biological evaluation of HO-1 inducers endowed with cytotoxic effects mediated by ferroptosis activation. Using the natural HO-1 inducer caffeic acid phenethyl ester (CAPE) as a chemical scaffold, new derivatives were synthesized by performing modifications in the cathecol moiety and in the phenethyl ester aromatic ring. Biological assays aimed at evaluating an imbalanced activity of ferroptosis key players identified that 2-(1H-indol-3-yl)ethyl cinnamate (compound 24) possesses improved anticancer activity toward the MDA-MB 231 triple negative breast cancer cell line when compared to CAPE. Increased ROS and LOOH levels, reduced GSH levels, imbalanced mitochondrial activity, and restored cell viability after ferrostatin-1 treatment suggested a ferroptotic mechanism of action, which did not involve GPX4 inhibition. Compound 24 represents an intriguing hit compound useful for the identification of novel ferroptosis inducers.

Analysis on effect of ultrasonic process on non-edible ester oils physiochemical properties

ABSTRACT Liquid insulation serves as an insulating medium in numerous high-voltage devices and it effectively dissipates the heat generated during operation. Typically, petroleum-derived mineral oil is employed as a liquid dielectric in oil bushings and transformers. Recent studies concentrated on developing alternative liquid insulation using natural esters derived from seeds and plants. Primary challenges associated with natural esters are viscosity and pour point, and it affects the cooling behavior of the insulation liquid. Hence, there is need to improve the viscosity and pour point performance of natural esters. This research focuses on non-edible natural esters, namely Jatropha oil, Karanja oil, and Mahua oil samples. Oil samples are subjected to ultrasonic treatment with an ultrasonic power of 500 W and frequencies of 20 kHz, 25 kHz, and 30 kHz for different time durations (30 min, 60 min, 90 min, and 120 min). The influence of ultrasonic wave frequency and different time periods on viscosity and pour point are investigated. As a result of this technique, due to the better cavitation process, Karanja oils viscosity is reduced to 39.76%, 32.53% and 25.30% for the ultrasonic frequencies of 20 kHz, 25 kHz, and 30 kHz respectively. Similarly, Mahua and Jatropha oil’s viscosities are also reduced due to the ultrasonic process.

Research progress in modified mineral oil, natural ester and mixed oil in transformers

AbstractThree kinds of typical insulating oil including mineral oil (MO), natural ester (NE), and mixed insulating oil used in transformers are reviewed. The basic physicochemical, electrical properties and engineering application of the oil were firstly introduced. Then, the nano‐modified mechanism for MO and NE is explored. The effects of various nanofillers on electrical properties, thermal conductivity and ageing stability of MO and NE are compared. Moreover, the preparation process of mixed insulating oil is described, and the enhancement of electrical performance, thermal ageing properties, and kinematic viscosity of mixed insulating oil are analysed. Finally, the performance parameters of nano‐modified MO, NE and mixed insulating oil are analysed, and the future development trend of insulating oil is also discussed.