The synthesis of monoacylglycerol from the glycerolysis of soybean oil catalyzed by alkaline ionic liquid was investigated as an alternative to the industrial glycerolysis promoted on environmentally unfriendly inorganic base catalysts. 1-Butyl-3-methylimidazolium hydroxide ([Bmim]OH) has a low catalyst activity for the glycerolysis, attributing to the bad thermal stability. 1-Butyl-3-methylimidazolium imidazolide ([Bmim]Im) possesses a strong base strength and satisfactory thermal stability, and it exhibits excellent catalytic activity for the glycerolysis. By optimizing the main reaction parameter, such as temperature, glycerol/oil molar ratio, [Bmim]Im dosage, and reaction time, the results demonstrate that it is possible to achieve a monoacylglycerol yield of ∼69% in the presence of [Bmim]Im at 200 °C, which is a higher value than those typically catalyzed by NaOH, KOH, Ca(OH)2, or MgO at 240 °C (40%–60%). Furthermore, the recovery and reuse of [Bmim]Im were also satisfactory, and the catalytic activity unchanged even after recycling six times.

•A new kind of asphalt-based porous carbon nanofiber networks has been synthesized via electrospinning technique.•The porous nature of nanofibers is beneficial for electrolyte penetration and sodium-ions transportation.•This kind of carbon nanofiber exhibits a reversible capacity of 210 mA h g−1 at current density of 500 mA g−1 even after 1000 cycles.A new kind of porous carbon nanofiber networks has been synthesized via electrospinning technique by using polyacrylonitrile and asphalt as carbon sources and Pluronic F127 as soft template. After stabilization and carbonization treatment, the obtained fabrics were directly utilized as self-supported anode materials for sodium-ion batteries. This kind of porous carbon nanofiber exhibits excellent sodium-ion storage properties, with a reversible capacity of 210 mA h g−1 at current density of 500 mA g−1 after 1000 cycles.

•Microwave treatment on crumb rubber (CR) degrades the ability of resistance to aging for CR modified asphalt.•Both microwave and TOR benefit to the low temperature behavior for the aged residue.•TOR has an edge over microwave treatment to improve compatibility and stability for CR modified asphalt.•TOR benefits to stability due to chemical reaction, which is verified by decreased intensity of peak at 966 cm− 1 in FTIR.More effective approaches need to be developed for solving the aging and thermal stability problems of crumb rubber modified asphalt (CRMA). This paper focused on microwave and trans-polyoctenamer (TOR). Therefore, various CRMA were prepared by crumb rubber (CR), microwave irradiated CR, TOR and base asphalt. The samples were subjected to thin film oven test (TFOT), pressure aging vessel (PAV) and high temperature storage tests. The effects of microwave and TOR were evaluated by rheological, FTIR and SEM tests. The results showed that microwave activated CR increases the risk of fatigue cracking caused by hardening effect of aging but endows the aged residue with stronger resistance to thermal cracking. These results attribute to the degradation and de-vulcanization effect of microwave on CR (verified by FTIR). TOR activated CRMA displayed a more obvious hardening effect and the improved low temperature creep behavior after aging. TOR improves the compatibility and storage stability of CRMA. Double bonds in TOR participate in chemical reaction and benefit to stability, which are verified by the decreased intensity of peak at 966 cm− 1. However, microwave treatment on CR has negative effect on stability of CRMA. Thermal stability was further verified by steady flow method.Download high-res image (379KB)Download full-size image

•This work revealed polymerized sulfur had delayed vulcanization effect on SBS modified asphalt.•The morphology indicated polymer domains tend to be smaller as the elongation of mixing time.•Viscosity of SBS modified asphalt decreases as polymerized sulfur content increases.•SBS modified asphalt with high level of polymerized sulfur shows the improved storage stability.The objective of this study was to investigate effects of polymerized sulfur on viscosity functions, morphology and storage stability of SBS modified asphalt, as compared to elemental sulfur. Viscosity functions including complex viscosity, steady flow viscosity and dynamic viscosity were measured by dynamic shear rheometer (DSR) and Brookfield viscosity rheometer. The morphology and microstructure of modified asphalt were observed using fluorescence microscopy and Fourier Transform Infrared spectroscopy (FTIR). The results revealed that the increment in viscosity of modified asphalt containing polymerized sulfur was slower than that of elemental sulfur. Vulcanization rate decreases with the increase of polymerized sulfur, i.e. delayed vulcanization effect. In morphology, large polymer domains progressively transform to the fine dispersed SBS phase with smaller dimensions as the elongation of mixing time; whereas a fine polymer phase was found for elemental sulfur at the initial stage of mixing, which is significant evidence of delayed vulcanization. Moreover, the FTIR results verify the decrease of unsaturation of poly-butadiene block and the formation of CS bond. Viscosities of asphalt with polymerized sulfur were always lower than those of elemental sulfur and decreased with the increase of polymerized sulfur content. SBS phase domain vulcanized by polymerized sulfur is larger than that of elemental sulfur and tends to become larger with the increase of polymerized sulfur content. Lastly, SBS modified asphalt with higher level of polymerized sulfur shows the improved storage stability.

•EVA molecule structure was optimized to improve performance of modified asphalt.•Comprehensive characterizations based on rheology were investigated.•Correlations of EVA molecule structure, morphology with rheology, stability were revealed.•The moderate VA content is pivotal to balance the viscoelastic properties and stability.Many efforts have been devoted to understand structure-property relationships of polymer-modified asphalts in order to improve their performance, but the acquired knowledge is still incomplete and never enough. The objective of this study was to optimize molecule structure parameter (vinyl acetate content) of ethylene-vinyl-acetate copolymer (EVA) for asphalt modification. The results indicated that viscoelastic functions (G′, G″ and G∗), viscosity and the percent recovery at high temperatures of modified asphalt present the maximum value, corresponding to sample with 18 wt% VA, as the increase of VA in EVA. While these functions decrease significantly when VA is more than 18 wt%. With respect to low temperature performance, the faster relaxation, lower stiffness and greater m-value are observed for samples containing higher VA contents, indicating enhanced cracking resistance. Furthermore, better stability corresponds to sample with higher VA. In microscopy, polymer-rich phase tend to be smaller in size with the increase of VA content. Besides, the distribution of EVA particle with higher VA in asphalt tend to be sparse and also be inconspicuous. Consequently, the moderate VA content, 18 wt% in this study, is pivotal to acquire the ideal high as well as low temperature performance and to balance the viscoelastic properties and stability.Download high-res image (227KB)Download full-size image

•CR activated by microwave and TOR reduces PAHs and sulfur compounds in asphalt fumes.•Microwave treatment on CR enhances relaxation performance of modified asphalt.•TOR greatly improves viscoelastic behavior of CR modified asphalt at high temperatures.This paper studied asphalt fume chemical composition, rheological properties and microstructure of asphalt with crumb rubber (CR) activated by microwave and trans-polyoctenamer (TOR). To that end, asphalt fume was trapped through laboratory fume generation and capture system, which was subsequently analyzed by Gas Chromatography-Mass Spectrometry system (GC–MS). Moreover, the rheological behavior and microstructure of CR modified asphalt (CRMA) were characterized by dynamic shear rheometer (DSR) and FTIR. The GC–MS results indicated that CR activated by microwave and TOR reduces the contents of PAHs and sulfur compounds, implying the lower toxicological potential of fume. TOR has the greater effect of reduction in the toxicological species. The rheological results indicated that CR activated by TOR significantly improves modulus, zero shear viscosity (ZSV), and recovery ability of CRMA at high temperatures, which cause asphalt binder having the stronger resistance to rutting. The enhancement in thermo-mechanics is due to chemical cross-linking among TOR, rubber, and asphalt, which was verified by FTIR results. On the other hand, microwave treatment on CR affects high temperature performance of CRMA negatively in comparison to the untreated CRMA. However, microwave treatment leads to the faster stress relaxation response of CRMA, indicating the stronger resistance to thermal cracking.Download high-res image (125KB)Download full-size image

•Addition of polyphosphoric acid (PPA) improves the thermal-rheological behavior of SBR modified asphalt.•PPA reduces dispersed polymer phase size.•The compatibility of SBR modified asphalt is improved by PPA.•High asphaltene content is beneficial for the improving effect of PPA.With the aim of improving the compatibility, high and low temperature properties of SBR modified asphalt, polyphosphoric acid (PPA) was added to achieve a further modification in this study. The effects of PPA and asphalt composition on physical properties, viscoelastic behavior, creep and recovery behavior, cracking resistance, compatibility and morphology of PPA/SBR modified asphalt were characterized, respectively. It was demonstrated that PPA dramatically enhanced the adhesion ability, high temperature elasticity and anti-rutting ability of SBR modified asphalt through deflocculation effect. The resistance against low temperature cracking of PPA/SBR modified asphalt underwent a degradation after first improvement as PPA increased. PPA also improved the compatibility between SBR and asphalt and decreased the dispersed polymer phase size, thus a more desirable microstructure was formed. Furthermore, relatively high asphaltene content of base asphalt was beneficial to achieve desired rheological properties of PPA/SBR modified asphalt. As a consequence, chemical reaction with PPA is an effective way to comprehensively improve the compatibility and thermo-rheological behavior of SBR modified asphalt.Download high-res image (58KB)Download full-size image

The application of asphalt with low penetration in warm areas to improve rutting-resistance has attracted great interest in recent years. Deoiled asphalt (DOA) and slurry, by-products of solvent deasphalting and fluid catalytic cracking respectively, are utilized with low value-added. The objective of this work was to prepare paving grade asphalt by blending various proportion of FCC slurry with DOA. The effect of chemical composition on viscoelastic characteristics of the blend was investigated and special emphasis was placed on the linear viscoelasticity and viscous flow behavior as well as on empirical tests. The results revealed that SARA fractions of the blends are close to asphalt and are compromise between DOA in which the content of asphaltenes is high and slurry in which is rich in aromatics. Also, SARA fractions have a significant influence on the rheological properties of the blends. Asphaltenes have been proved to enhance the moduli of asphalt and low penetration blends have demonstrated high rutting and deformation resistance especially at high temperatures. Taking into account the balance between workability and in-service performance, application of the 40 wt% slurry in DOA is highly recommended. It is indicated that a more inferior aging resistance with the increase of slurry in DOA. As a result, it is a highly effective and meaningful way to utilize DOA and FCC slurry.

Two novel decyloxyphenylquinoxaline-based donor-acceptor (D-A) electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3-bis(4-decyloxyphenyl)-5,8-bis(3,4-dimethoxylthiophen-2-yl)quinoxaline] (P1) and poly[2,3-bis(4-decyloxyphenyl)-5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)quinoxaline] (P2), are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance (NMR), mass spectrometry (MS), scanning electron microscopy (SEM), cyclic voltammetry (CV), ultraviolet-visible absorption spectrometry (UV-Vis) and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% (595 nm), 30% (839 nm) and 69% (1500 nm) transmittance changes (ΔT%), while P2 exhibited 32% (740 nm), 71% (2000 nm) at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.

•CR/SBS modified asphalt shows increased viscoelastic moduli and viscosity.•Moderate asphaltenes and high aromatics are necessary for this modification.•CR/SBS modified asphalt appears obvious phase separation at the storing period.•CR could be an alternative for reducing SBS from view of economic and environment.The rheological properties and storage stability of CR/SBS modified asphalt have been investigated in this study. Crumb rubber (CR) as well as SBS was blended with asphalt having different chemical composition to prepare CR/SBS modified asphalt by high-shear mixer. Linear viscoelastic and viscous measurements, fluorescence microscopy as well as storage stability tests were performed on unmodified and CR/SBS modified asphalt. The results revealed that the addition of CR/SBS to asphalt produces a remarkable improvement in viscoelastic characteristics and viscosity compared with neat asphalt. Consequently, an enhanced resistance to permanent deformation is expected in road. Crumb rubber replacing parts of SBS to produce CR/SBS modified asphalt is feasible because failure temperature, moduli and viscosity undergo a significantly increase when the dosage of SBS exceeds 1%. The chemical composition of base asphalt for this special modification is crucial. In other words, moderate asphaltenes and high aromatics are suggested in order to achieve desired rheological properties. CR/SBS modified asphalt appears obvious phase separation at the storing period resulting from coalescence of SBS particle at the top of sample and sedimentation of rubber particles at the bottom. Thus, CR/SBS modified asphalt must be used swiftly after which has been produced owing to its poor storage stability. Anyhow, crumb rubber could be an alternative for reducing use of virgin SBS from economic and environmental point of view.

•The relationship of microstructure with viscous behavior and storage stability is uncovered.•The flow behavior tends to turn into non-Newtonian fluid with increasing particle size.•The features of dispersed rubber particles in asphalt are elongated or strip-type.•Viscosity increase with particle size owing to ratio of length and diameter increasing.Recycled-polymer modified asphalt has been extensively used in road construction, especially the recycled tire scrap rubber-modified asphalt (TSRMA). However, the main problem during the application of TSRMA is poor storage stability which finally affects the service performance of the pavement. The objective of this work is to evaluate viscous properties, storage stability and morphology of TSRMA and to reveal the relationship of microstructure with rheological behavior and storage stability. With this aim, two different penetration grade asphalts were modified by rubber particles with various mean diameter in a four-paddle mixer at 170 °C. Steady state flow measurements, frequency sweep tests in linear viscoelastic region, storage stability tests as well as fluorescence microscopy were carried out on mixes. Rheological evaluation reveals that the addition of tire scrap rubber to asphalt lead to a significant increase in viscosity at 60 °C, improving rutting or permanent deformation resistance. Furthermore, the increase in particle size causes an enhancement in viscosity and the steady flow behavior tend to turn into non-Newtonian fluid with increasing particle size and temperature. Storage tests presented that the viscosity of samples obtained from the bottom section of a tube are always higher and the difference also becomes significant as the increase of rubber particles size, tending to poor stability. Fluorescence microscopy shows that dispersed particles in asphalt are the elongated features or strip-type and the aspect ratio (length/diameter) increases with particle size. In addition, smaller particle tend to be unobvious in matrix under microscopy view, indicating improved compatibility between rubber and asphalt.

The effect of emulsification on the styrene–butadiene–styrene (SBS) chemically modified bitumens (CMBs) is studied by conventional tests, differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectroscopy. Compared to CMBs, modified bitumen emulsion residues (MBERs) exhibit higher temperature susceptibility, inferior resistant to cracking and deformation, lower elastic recovery and storage stability whereas these properties are improved substantially relative to base bitumens. DSC results show that the thermostability of CMBs decreased slightly after emulsification which indicate the emulsification exerts very little effect on the thermal property of CMBs. The FTIR results do not indicate any chemical reaction exists on CMBs during the emulsification.Highlights▸ Effect of emulsification on chemically modified bitumens is determined. ▸ Emulsion residues exhibit inferior properties relative to modified bitumens. ▸ Emulsion residues show improved performance relative to base bitumens. ▸ Emulsification exerts slight thermal impact on modified bitumens. ▸ Microstructure of modified bitumens does not change during emulsification.