Good Low-temperature Properties Research Articles

Rubber-assisted and modulated epoxy topological network for developing fatigue-resistant, high-strain-cycle high performance shape memory polymer composites

High performance shape memory polymer (HPSMP) has a wide range of application such as smart device, smart mold. In this study, we designed a rigid-flexible shape memory epoxy with flexible chain segment as the main chain and rigid benzene ring as the side group. Meanwhile, carboxyl-terminated nitrile butadiene rubber (CTBN) was accessed into the epoxy main chain as a fatigue-resistant functional filler. The results showed that the flexible backbone plays a major role in improving the ductility. The superior fatigue-resistant shape memory cycling performance was synergistically achieved by modulating the epoxy topological network through altering the disulfide cross-linker prompted by CTBN, and the materials exhibited good high and low-temperature resistant mechanical properties. Comparatively, it is found that disulfide bonding can significantly improve the tensile property and thermal stability for epoxy. The synergistic effect between the elastic chain segments in CTBN and the flexible backbone achieves excellent shape recovery ratio. Therefore, the rational structural design provides an effective way to develop HPSMP, which can expand the application areas for HPSMP.

Tandem hydroalkylation and deoxygenation of lignin-derived phenolics to synthesize high-density fuels

Lignin is the most abundant naturally phenolic biomass, and the synthesis of high-performance renewable fuel from lignin has attracted significant attention. We propose the efficient synthesis of high-density fuels using simulated lignin cracked oil in tandem with hydroalkylation and deoxygenation reactions. First, we investigated the reaction pathway for the hydroalkylation of phenol, which competes with the hydrodeoxygenation form cyclohexane. And then, we investigated the effects of metal catalyst types, the loading amount of metallic, acid dosage, and reactant ratio on the reaction results. The phenol hydroalkylation and hydrodeoxygenation were balanced when 180 °C and 5 MPa H2 with the alkanes yield of 95%. By extending the substrate to other lignin-derived phenolics and simulated lignin cracked oil, we obtained the polycyclic alkane fuel with high density of 0.918 g·ml−1 and calorific value of 41.2 MJ·L−1. Besides, the fuel has good low-temperature properties (viscosity of 9.3 mm2·s−1 at 20 °C and freezing point below −55 °C), which is expected to be used as jet fuel. This work provides a promising way for the easy and green production of high-density fuel directly from real lignin oil.

High-Temperature Oxidized Mo2CTx MXene for a High-Performance Supercapacitor.

Molybdenum carbide (Mo2CTx MXene) did not possess suitable properties for supercapacitors. Herein, a short oxidation method of Mo2CTx in air at moderately high temperatures is proposed for fabricating a Mo2C/MoO3 heterostructure. The stability of Mo2CTx in air up to 700 °C and the phase transition at higher temperatures are confirmed. Such a heterostructure is beneficial in reducing the diffusion energy barrier of H+. In the aqueous system, the Mo2C/MoO3 electrode delivers a capacitance of up to 811 F g-1. A fully assembled symmetric solid-state supercapacitor delivers 224 F g-1 with an excellent retention rate of 91.05% after 7500 cycles. Besides, the supercapacitor can work at the low temperature of -60°, showing good low-temperature properties. The approach presented in this work opens a promising way to turn a neglected MXene, assumed to be unsuitable for supercapacitors, into one of the top-performing supercapacitor electrodes.

Properties and Analysis of Liquid Alternative Fuels III: Vegetable Oils and Hydrotreated Vegetable Oils

The importance of alternative fuels and biofuels is constantly growing due to energy security, sustainability, and social responsibility. This article is another in a series of review articles designed to recapitulate information on the required properties of individual alternative fuels, their testing methods, and the significance of individual analyses. This article is focused on fuels based on vegetable oils and hydrotreated vegetable oils. Rapeseed oil is a triglyceride-based fuel that can be burned in modified diesel engines. Modification of the engine consists in the inclusion of preheating of the fuel or modification of the injection system, due to the high viscosity of this fuel. Rapeseed oil and vegetable oils in general have a higher oxygen content than conventional diesel fuels, which is associated with a lower energy content than that of diesel fuels. Compared to diesel, vegetable oils have a higher density, a lower cetane number, and a significantly higher flash point and viscosity. Vegetable oils also have low oxidative stability. Physical properties monitored in rapeseed oils include density, viscosity, flash point, and calorific value. From the chemical properties, the iodine number, acidity number, water content, calcium, magnesium, sulfur, and phosphorus are monitored. From the other properties, oxidative stability, ignitability, ash content, carbonation residue, content of impurities, and appearance are monitored for rapeseed oils. HVO is a high-quality fuel for standard diesel engines. Due to the hydrocarbon character of HVO, no engine modification is required. HVO has a very high cetane number, very good low-temperature properties, optimal viscosity, high flash point, excellent oxidative stability, and a very low content of undesirable contaminants such as aromatic hydrocarbons, sulfur, nitrogen, and oxygen-containing compounds. Compared to diesel fuels, HVO has a lower density. The observed qualitative parameters and testing methods are very similar to those of conventional diesel fuel B7. The main difference lies in the modified determination of aromatic hydrocarbons.

PRODUCTION OF THERMOSTABLE ROAD BITUMENS BY THE METHOD OF "OXIDATION-COMPOUNDING"

The paper proposes a technology for producing petroleum road bitumen by compounding deeply oxidized bitumen with tar, pre-oxidized to various temperatures, in order to produce binders stable to the processes of thermo-oxidative aging. The rate of technological and chemical aging of tar and bitumen has been studied. It was found that tar is most susceptible to technological, and bitumen to chemical aging. It is shown that the use of tar pre-oxidation technology is a promising direction in bitumen production in the production of standard grades of bitumen binders. The obtained compounded bitumens have high extensibility values at 250C and maximum tensile force, which characterizes their high cohesive properties, as well as high values of the needle penetration depth at 00C and low brittleness temperatures, which indicate good low-temperature properties of bitumen. It has been revealed that the use of oxidized tar with a softening point of 360C during compounding with deeply oxidized bitumen can achieve the minimum values of softening temperature change after aging and obtain standard bitumen grades BND 70/100 and BND 100/130 according to GOST 33133-2014. The resulting compounded bitumen is less susceptible to destructive and thermo-oxidative aging processes and can be effectively used for paving

Friction and Wear Properties of CoCrFeNiMnSnx High Entropy Alloy Coatings Prepared via Laser Cladding

Due to its unique single-phase multivariate alloy characteristics and good low-temperature mechanical properties, CoCrFeNiMn high entropy alloy (HEA) has attracted the interest of many researchers in recent years. In this paper, to improve the wear resistance of Q235 alloy steel surface, CoCrFeNiMnSnx HEA coatings were prepared on the surface of Q235 steel via laser cladding. X-ray diffractometry, optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectrometry were used to determine the microstructure and chemical composition. The research findings revealed that the CoCrFeNiMn HEA coatings were formed from a single FCC phase. As the Sn content in the coating increased, a new MnNi2Sn phase formed. Microhardness and friction and wear results showed that when the mole content of Sn was 0.2, the hardness of the CoCrFeNiMn HEA coating was increased by approximately 45%, the friction coefficient decreased by 0.168, and the wear loss decreased by 16.6%. Three-dimensional noncontact morphology and SEM results revealed that the wear mechanisms of CoCrFeNiMn HEA coatings were abrasive wear, delamination wear and a small amount of oxidative wear under dry friction conditions, whereas the friction mechanisms of CoCrFeNiMnSn0.2 HEA coatings were primarily abrasive wear and oxidative wear.

Synthesis, Characterization, Tribological and Rheological Properties of Di (2-Butyloctyl) Dicarboxylate Esters for Environmentally Friendly Biolubricant Applications

The passion for replacing petroleum-based lubricants with renewable and sustainable alternatives has encouraged the development of plant-based biolubricants. In this work, a synthesis of di (2-butyloctyl) dicarboxylate esters for biolubricant base oil was carried out through esterification between selected dicarboxylic acids (succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, and dodecanedioic) with branched alcohol (2-butyl-1-octanol) catalyzed by sulphuric acid. The synthesized dicarboxylate esters showed high yield percentages in the range of 88 – 98 %. The chemical structures were confirmed using FTIR and NMR (1H and 13C) spectroscopies. The lubrication results show that the synthesized dicarboxylate esters have very good low-temperature properties with pour points less than −70°C. Furthermore, the esters' flash point, oxidative stability, and viscosity indices increased with their molecular weight. Tribological results have indicated that the tested dicarboxylate esters have good lubrication properties with a low friction coefficient (µ) range of 0.18-0.34 at 40 and 100°C. Rheological analysis showed that the di (2-butyloctyl) dicarboxylate esters were non-Newtonian. The synthesized products were categorized as ISO VG 32 and compatible with some selected commercial lubricants. These make them plausible to be used hydraulic fluids for various industrial applications such as gear, hydraulic, and transmission fluids in heavy machinery usage.

Effect of molecular structure on low-temperature properties of bitumen based on molecular dynamics

Low-temperature cracking is one of the most prevalent distress in asphalt pavement, closely related to the bitumen low-temperature properties. However, the molecular mechanism of low-temperature properties of bitumen is still ambiguous. This paper focuses on studying the effects of molecular structure on the low-temperature properties of bitumen by molecular dynamics (MD) simulation. The low-temperature viscoelasticity and glass transition temperature of bitumen were measured by dynamic shear rheometer (DSR) and differential scanning calorimeter (DSC) experiment. The MD models containing 20 kinds of molecules were constructed to represent the bitumen and validated by density, shear modulus and glass transition temperature. Furthermore, the effects of molecular structure on the low-temperature properties were analyzed by relative density, mean square displacement (MSD), radial distribution function (RDF), and potential energy. The DSR and DSC results showed that the low-temperature properties ranking of the bitumen is HY90 > LH50 > LH90 > LH70. The relative density and RDF curves showed that the increasing aromatic carbons in resins and aromatics reduce the asphaltenes aggregation degree and improve the low-temperature properties by promoting the formation and dispersion of asphaltene-resin aggregates. The MSD curves indicated that the bitumen with a high average diffusion coefficient has good low-temperature properties. The increase of aromatic carbons improves the diffusion coefficient by forming molecules with low molecular mass. Moreover, non-bond energy positively correlates with the low-temperature properties of bitumen. The low-temperature properties of bitumen can be optimized by increasing the resins and aromatics, or adding molecules with high aromatic carbon content and diffusion coefficients.

Synthesis and comprehensive fuel properties of mono-substituted alkyl adamantanes for advanced aerospace propulsion

Design and choice of fuels continue to be improved for aviation propulsion, and alkyl adamantanes have attracted great attention due to their high density, good low-temperature properties and potential characteristics. Herein, we reported a facile route to synthesize mono-substituted alkyl adamantanes via modified Grignard coupling (followed with one-step hydrodeoxygenation), including 1-ethyl-adamantane, 2-ethyl-adamantane, and 1-n-propyl-adamantane with high yields (> 75%). The process was modified via concentrating the Grignard reagents and altering the solvent, and one-step hydrodeoxygenation catalyzed by commercial Pd/C and zeolites was developed. Subsequently, comprehensive characteristics of alkyl diamondoid series, such as oxidation stability and combustion properties, were evaluated using pressure differential scanning calorimetry, rapid small-scale oxidation test, and hot-plate ignition test. Also, the specific impulse of alkyl diamondoids were revealed by theoretical calculation. The high-density alkyl diamondoids present adequate oxidation stability and possess better combustion characteristics over JP-10, thus can be considered as potential high-energy-density fuel for aerospace propulsion.

Lubrication properties of dodecanedioate esters-based bio-lubricant

Interest in the synthesis of new bio-lubricants with improved lubricity properties and higher quality is increasing. This study aimed to evaluate the bio-lubrication properties of synthesized dodecanedioate esters-based bio-lubricant. Thirteen samples of dodecanedioate esters with different chemical structures were synthesized. The results showed that di-2-methylbutyl dodecanedioate (D2MBD), di-2-ethylbutyl dodecanedioate (D2EBD), and di-2-ethylhexyl dodecanedioate (D2EHD) showed good low-temperature properties with very low pour point (PP) values of -45 oC, -35 oC, and -55 oC, respectively. Di-oleyl dodecanedioate (DOlD) showed a remarkable flash point (FP) value of 300 oC; however, it showed poor oxidative stability (OXS) at 177 oC. The results showed increases in flash point (FP), viscosity index (VI), and oxidative stability (OXT) with increasing carbon chain length and branching in the employed alcohol. Furthermore, friction coefficient, Newtonian and non-Newtonian properties were tested. The results showed that the tested dodecanedioate esters, which have high molecular weight had a low friction coefficient, and they were classified as non-Newtonian fluids except DOLD was classified as a Newtonian fluid. In general, based on the results, the branched dodecanedioate esters can be used as lubricant without additives.

Reduced graphene oxide enhanced emulsification for one-pot synthesis of high-density jet fuel

Synthesis of jet fuel with high density, good low-temperature property and high thermal stability is significant to aerospace industry. Here, a great-performance jet fuel blending including bi- and tri-cyclic hydrocarbons (C10 ~ C16) is synthesized with high yield through reduced graphene oxide (rGO) assisted H2SO4 catalytic one-pot reaction of cyclopentanol and methylcyclopentane. The reaction occurs through a consecutive way of dehydration, alkylation, rearrangement and hydrogen transfer. Carbon-based materials especially rGO are used as additive to increase the carbon yield by promoting the emulsification of reactants in sulfuric acid. Promoted emulsification improves the alkylation of cyclopentanol with methylcyclopentane and makes the hydrogen transfer easier, which highly increases the conversion of methylcyclopentane (54.9%), the carbon yield (83.2%) and the selectivity (97.3%) of products. Finally, a jet-fuel-ranged blending with overall yield of 71.8% is obtained by distillation, which shows high density of 0.90 g/mL, low freezing point of ＜-72 °C and a high oxidation onset temperature of 195.0 °C. This work provides a simple, efficient and low-cost way to synthesize high performance jet fuel from biomass.

Synthesis of strained high-energy rocket bio-kerosene via cyclopropanation of myrcene

With the rapid development of spacecraft such as rocket, it is increasingly important to develop high-energy and sustainable fuels. Biofuels synthesized from biomass derivatives provide great convenience for sustainable development. In this work, we reported a route for synthesis of high-energy cyclopropane bio-kerosene by cyclopropanation of myrcene with zinc carbenoid. The reaction conditions including reaction time, reaction temperature, solvent and molar ratio were optimized. Finally, a tricyclic cyclopropane bio-kerosene was synthesized with 69.8% yield under optimum conditions (i.e. zinc carbenoid synthesis temperature of −15 °C, cyclopropanation temperature of 25 °C and solvent of dichloromethane). Importantly, this bio-kerosene possesses a high specific impulse of 328.25 s, much better than the commercial rocket kerosene RP-1, as well as a high net-heat-value of 43.4 MJ/kg and good low-temperature properties.

Rheological properties of SBS/CR-C composite modified asphalt binders in different aging conditions

Abstract A type of styrene-butadiene-styrene (SBS) and crumb rubber (CR) composite modified asphalt (CMA) binder with a chemical (-C) method was proposed in this research. Dynamic shear rheometer (DSR) tests were conducted at different frequency and temperature to evaluate rheological properties of SBS/CR-C CMA in different aging conditions. Rheological master curves were also constructed to survey its rheological properties in a broad range of frequencies and temperatures. Based on test results, it was concluded that the rheology of SBS/CR-C CMA prepared by ultra-fine embedding grafting technology has been improved over a wide temperature range, showing good high and low temperature properties. In the low temperature domain, the asphalt provides good fatigue resistance attributed to the elastic property of CR. And in the high temperature domain, the copolymer network significantly improves the elastic response of SBS/CR-C CMA, showing better deformation recovery. In addition, short- and long-term aging enhance the shear deformation resistance and elastic behavior of SBS/CR-C CMA, but weaken the low-temperature cracking and fatigue resistance performance. SBS/CR-C CMA has excellent anti-aging property.

A novel wheel-confined composite as cathode in Li-S batteries with high capacity retention

High energy density Li-S battery has attracted broad attention; however the capacity retention is still non-ideal. The major challenge is to find a way to effectively prevent the shuttle effect of the lithium polysulfides during charging/discharging. Here, we present a novel wheel-confined composite consisting of MnO2 nano-rod as wedge and SnO2 sphere as the skeleton filled with sulfur, which was synthesized using a facile chemical method. The battery with the S@MnO2@SnO2 composite as cathode exhibits a capacity as high as 1323 mAh g−1 at 0.1 C and a high capacity retention of only 0.03% decay per cycle over 500 cycles, which indicates a greatly reduced shuttle effect in Li-S batteries. The battery also shows good rate-performance and low-temperature properties. In addition, the I-V measurements and the first-principle calculations have demonstrated an enhanced electron transfer through the composite.

Excellent low-temperature catalytic performance of nanosheet Co-Mn oxides for total benzene oxidation

A series of CoaMnbOx oxides (a/b = 1:1∼7:1) at 500 °C and Co2Mn1Ox at a temperature range of 300–700 °C were prepared by an oxalate co-precipitation method and evaluated of catalytic performance for benzene total oxidation. It is found that Co2Mn1Ox catalyst displays the best activity among all the CoaMnbOx oxides. The typical uniform nanosheet morphology plays a vital role in achieving the relatively high activity of Co2Mn1Ox. A detailed characterization has illustrated that the calcination temperature is also an important factor to influence the structure, physico-chemical properties and thus catalytic performance of Co2Mn1Ox. Co2Mn1Ox calcinated at 300 °C (CM300) presents pretty thin nanosheet and small particle size of 6.6 nm. It displays a better low-temperature catalytic activity than those obtained at temperatures of >300 °C: under the conditions of 20,000 mL g−1 h−1 and 1500 ppm of benzene, the temperature at 90% conversion of benzene oxidation is 191 °C, which is lower than that of some related reports in the literatures. Furthermore, CM300 performed excellent long-term stability. It is concluded that the superior catalytic performance of CM300 is associated with its relatively large specific surface area, good low-temperature redox property, abundant active oxygen species and active components (Co2+ and Mn4+). Co-Mn oxides will be the potential alternative of precious metals for the removal of volatile organic compounds in the industrial field.

Layer-stacked Sb@graphene micro/nanocomposite with decent Na-storage, full-cell and low-temperature performances

Resolving the large volume changes and achieving the ultrafast charge-discharge capability for the alloy anode of sodium-ion batteries (SIBs) are needed urgently. Rational design of unique structure is an effective strategy to solve these problems. Herein, we reported a facile route to synthesize a layer-stacked Sb@graphene (LS-Sb@G) micro/nanocomposite via solvothermal method by using a mild reducing agent. In the LS-Sb@G, the Sb nanosheets are uniformly pasted on the graphene matrix and embedded into the interlayers, which leading to the formation of tight layer-by-layer micro/nanostructure. When employed as anode materials for SIBs, the unique structural characteristics offer the LS-Sb@G micro/nanocomposite with impressive Na-storage properties, such as high Na-storage capacity of 495.2 mAh/g after 100 cycles at 125 mA/g and decent rate capabilities up to 6 A/g. In addition, the LS-Sb@G electrode achieves superior electrochemical performance with a high reversible capacity of 116.5 mAh/g at 0.1 C (1 C = 120 mA/g) for sodium-ion full cells. Moreover, we firstly studied the low-temperature Na-storage performance of Sb-based composite at −20 °C. The LS-Sb@G composite demonstrated good low-temperature properties (e.g., 506.6 and 472.5 mAh/g at 25 and 50 mA/g at −20 °C, respectively) for SIBs, which endow great promise as an anode material for the normal operation of electric vehicles under low temperature condition.

The performance of manganese-based catalysts with Ce0.65Zr0.35O2 as support for catalytic oxidation of toluene

Mesoporous Ce0.65Zr0.35O2 composites are synthesized by co-precipitation method and a series of novel MnOx/Ce0.65Zr0.35O2 monolithic catalysts with different content of manganese oxides are prepared for toluene catalytic oxidation. The results show that the catalytic activity of Ce0.65Zr0.35O2 is promoted by introduction of manganese and influenced remarkably by the amount of MnOx. In particular, the catalyst with 15wt.% MnOx loading performs best activity in view of the lowest complete conversion temperature of 250°C at a GHSV of 12000h−1. According to the characterizations of N2 adsorption-desorption, XRD, SEM-EDX, H2-TPR, O2-TPD and XPS analyses, the superior catalytic activity could be attributed to the well-dispersed MnOx species, good low-temperature redox property, more Mn4+ species and more available surface and lattice oxygen species. Additionally, the optimized catalyst shows high stability during the thermal aging experiment and long-term testing experiment, and it also shows a good activity under the condition of high gas hourly space velocity, which presents a well application prospect.

Zwitterionic Polymer P(AM-DMC-AMPS) as a Low-Molecular-Weight Encapsulator in Deepwater Drilling Fluid

In deepwater oil and gas drilling, the high-molecular-weight encapsulator aggravates the thickening of the drilling fluid at low temperatures. Therefore, it is hard to manage the downhole pressure, and drilling fluid loss occurs. In this paper, a zwitterionic polymer P(AM-DMC-AMPS) which was the terpolymer of acrylamide, methacrylatoethyl trimethyl ammonium chloride, and 2-acrylamido-2-methylpropane sulfonic acid, was developed as a low-molecular-weight encapsulator. It was characterized by Fourier transform infrared spectrum analysis, nuclear magnetic resonance, and gel permeation chromatography. Moreover, the low-temperature rheology, shale inhibition and filtration properties of water-based drilling fluids (WBDFs) containing different encapsulators were experimentally investigated and compared. The results showed that the molecular weight of P(AM-DMC-AMPS) was about 260,000, much lower than that of the conventional encapsulators. In the deepwater drilling temperature range 4–75 °C, WBDF containing P(AM-DMC-AMPS) had lower and more stable rheological property because of its short molecular chains. The high shale recovery rate and low swelling rate indicated its strong shale inhibition performance, owing to its adsorption on the clay surface and the wrapping effect through both hydrogen bonding and electrostatic interaction. It also improved the filtration property of WBDF, and was compatible with other WBDF components. This product is expected to simultaneously realize the good encapsulation performance and low-temperature rheological property for deepwater drilling fluid.

Behaviour of Natural Rubber in Comparison with Structural Steel, Aluminium and Glass Epoxy Composite under Low Velocity Impact Loading

This paper presents the low velocity gravity impact behaviour of various materials (Structural steel, Aluminium, Rubber and Glass Epoxy composite). A comparison of the above said materials is reported considering various parameters such as Total Energy, contact force, deformation, von mises stress and strain and specific energy absorbed are carried out. The results confirmed that rubber absorbs more energy compared to other materials considered thus highlighting its potential use in structural applications subjected to low velocity impact. The natural rubber in many ways is an ideal polymer for dynamic or static engineering applications. It has excellent dynamic properties, with a low hysteresis loss, and good low temperature properties, it can be bonded well to metal parts, has high resistance to tear and abrasion and it is relatively easy to process. Natural rubber composites find technological interest in that they exhibit additional features like biodegradability and renewability, along with the inherent stiffness, low cost and low density. The great advantage of natural rubber based on its linear elasticity, high strength, fatigue life and excellent adhesion to metals makes it well suited for structural or semi structural applications

Good Low-Temperature Properties of Nitrogen-Enriched Porous Carbon as Sulfur Hosts for High-Performance Li-S Batteries.

Despite the increased attention devoted to exploring cathode construction based on various nitrogen-enriched carbon scaffolds at room temperature, the low-temperature behaviors of Li-S cathodes have yet to be studied. Herein, we demonstrate the good low-temperature electrochemical performances of nitrogen-enriched carbon/sulfur composite cathodes. Electrochemical evaluation indicates that a reversible capacity of 368 mAh g(-1) (0.5 C) over 100 cycles is achieved at -20 °C. After returning to 25 °C, a capacity of 620 mAh g(-1) (0.5 C) is achieved over 350 cycles with a low-capacity attenuation rate (0.071% per cycle) and an initial capacity of 1151 mAh g(-1) (0.1C). This positive electrochemical property was speculated to result from the good surface chemistry of the various amine groups in the nitrogen-enriched carbon materials with enhanced polysulfide immobilization.