Preparation of β-cyclodextrin/SBS modified asphalts for the improvement of anti-aging,rheological property,and storage stability

Styrene-butadiene-styrene (SBS) modified asphalt (SMA) has been widely used in road engineering for decade. However, the phase separation of SMA was obvious during the transport and SBS degraded after aging. To resolve these problems, β-cyclodextrin (β-CD) was used to modify SMA in this work. Conventional properties, storage stability, the effect of short-term aging on the morphology, and rheological property for SMA and β-CD/SMA were investigated. The softening point of modified asphalt reached to the maximum of 66.7°C when 1 wt% β-CD was added to SMA, where the penetration had shown the minimum of 80.8 dmm. In addition, the ductility of β-CD/SMA increased to the maximum of 797 mm when the content of β-CD was increased to 5 wt%. Furthermore, incorporation of β-CD improved the storage stability of SMA. Importantly, the aggregation of SBS was observed in β-CD/SMA, but modifiers distributed uniformly after a short-term aging. The rutting resistance and antiaging performances of SMA were also improved by the addition of β-CD. Considering the comprehensive properties of modified asphalt, the optimum content of β-CD was found to be 2 wt%.     

Synthesis of water dispersible reduced graphene oxide via supramolecular complexation with modified β-cyclodextrin

A noncovalent functionalization of the edges of reduced graphene oxide (RGO) with β-cyclodextrin-graft-hyperbranched polyglycerol (β-CD-g-HPG) was successfully performed via a host-guest interaction. The results showed that β-CD-g-HPG disperses the graphene sheets better than pure β-CD or HPG. The resulted supramolecular structure is stable in neutral water medium more than one week. However, in acidic medium the host-guest interaction is collapsed and graphene nanosheets precipitate.     

Chiral adsorption of phenylalanine by α-, β-cyclodextrin modified layered double hydroxides

The chiral adsorption of racemic phenylalanine (Phe) by carboxymethyl-α/β-cyclodextrin-intercalated Zn-Al layered double hydroxides (CM-α/β-CD-LDHs) has been studied. The adsorption isotherms of chiral excess adsorption and the total adsorption of Phe by these CM-α/β-CD-LDHs have been investigated. CM—CD-LDHs were found to be more suitable for chiral recognition of Phe than CM—CD-LDHs. Furthermore, the intraparticle diffusion model is successfully validated in this work. Intraparticle effective diffusivities (D _eff ) of Phe in these CM-α/β-CD-LDHs macroparticles were determined from the homogeneous Fickian diffusion model at various temperatures.     

Determination of lisinopril using β-cyclodextrin/graphene oxide-SO3H modified glassy carbon electrode

An electrochemical method has been successfully demonstrated for sensitive determination of lisinopril with β-cyclodextrin-graphene oxide-SO₃H composite modified glassy carbon electrode (β-CD/GO-SO₃H/GCE). Cyclic voltammetry, differential pulse voltammetry, and chronocoulometry were used to investigate the electrochemical behavior of lisinopril at β-CD/GO-SO₃H/GCE. The cyclic voltammetric results indicate that β-CD/GO-SO₃H/GCE can remarkably enhance electroactivity toward the oxidation of lisinopril in buffer solutions. The electrochemical behavior was further exploited as a sensitive detection scheme for the lisinopril determination by differential-pulse voltammetry. Under optimized conditions, the concentration range and detection limit were 0.21–190.4 and 0.11 µM (S/N = 3), respectively. The method was successfully applied to assay the drug in human serum.     

Crosslinking of β-cyclodextrin and combining with ammonium polyphosphate for flame-retardant polypropylene

This work presents the synthesis of crosslinked hexamethylene diisocyanate β-cyclodextrins (HDI-CDs) by reacting β-cyclodextrin (β-CD) with HDI as a crosslinking agent at different feed ratios. As a novel char-forming agent, the HDI-CDs are combined with ammonium polyphosphate (APP) and applied in polypropylene (PP) to form intumescent flame-retardant composites. The structure of HDI-CDs is characterized by Fourier transform infrared spectra (FTIR), ¹³C nuclear magnetic resonance spectroscopy, and nitrogen adsorption–desorption test. The thermogravimetric analysis (TGA) results indicate that HDI-CDs have better char-forming performance than β-CD. FTIR spectra, X-ray diffraction, and Raman spectra characterization demonstrate that the reaction between HDI-CDs and APP contributes to the formation of a more stable char layer than β-CD and APP. According to the results of TGA, scanning electron microscopy, limiting oxygen index (LOI), UL-94, and X-ray photoelectron spectroscopy test, when the crosslinking degree of HDI-CDs is high enough (not less than β-CD:HDI = 1:3.6), the PP/APP/HDI-CDs composites can form a compact and dense char layer during combustion. Among all composites, PP/APP/HDI-CD(4) shows the best flame-retardant performance, which can pass the UL 94 V-0 rating with an LOI value of 32.8% when the loading of flame retardants is 28 wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48320.     

A modified dilatometer for fast evaluation of “solids content” in fats

Summary A change was made in the dilatometer design, allowing a substantial reduction in the time required to complete a “Solids Content” determination in edible fats. The modified dilatometer has a hollow stopper that extends nearly to the bottom of the dilatometer bulb, thereby giving the fat sample the shape of a hollow cylinder. The surface area effecting heat transfer is increased, and the thickness of the fat sample is reduced, resulting in a considerable reduction in the time required to obtain temperature equilibrium throughout the fat sample.     

Fabrication of aerogels from cellulose nanofibril grafted with β-cyclodextrin for capture of water pollutants

Journal of Porous Materials - Interactions at the molecular and surface chemistry are some of the key factors that determine the adsorption capacity of pollutants and emerging contaminants in...     

Synthesis,characterization and As(III) adsorption behavior of β-cyclodextrin modified hydrous ferric oxide

This study investigates the adsorption of As(III) on β-cyclodextrin modified hydrous ferric oxide (HCC). This is characterized by XRD, FESEM, AFM, XPS, BET, surface site concentration and FTIR. The modification of hydrous ferric oxide (HFO) surface by β-cyclodextrin provides ample OH groups which in turn increase As(III) adsorption on HCC compared to HFO. The adsorption remains almost constant in pH range 3–8 which decreases at higher pH (>8) and followed monolayer and pseudo first order kinetics. It is spontaneous at 303 K with increasing entropy and decreasing enthalpy. Thus HCC is found to be more efficient adsorbent than HFO.     

Synthesis and structure–property relationship of polyester-urethanes and their evaluation for the regeneration of contractile tissues

The structure–property relationship of degradable polyurethanes from non toxic building blocks was studied by synthesising four different biodegradable poly(ester urethanes) from poly(ε-caprolactone) (PCL) diol, 1,4-diisocyanatobutane and different chain extenders. For instance, the chain extenders were an amino acid derivative diamine, an amino acid derivative diol, a cyclic diol and a custom made diamine, containing an enzymatically degradable peptide (Ala–Ala sequence). Physicochemical and morphological characterisation (SEC, DSC, DMA, AFM) was performed, showing the influence of the chain extender on the polyurethane properties. A correlation between surface domain morphologies and thermal properties was highlighted and a relationship between the biological response and surface morphologies was observed. Collecting mechanical characterisation and myoblast cell culture results together, the polyurethane synthesised with the amino acid derivative diamine resulted the most promising candidate for fabricating scaffolds supporting the regeneration of muscle tissues.     

Viscosity and thermal conductivity of ZnO–water-based nanofluids stabilized by grafted SMA-g-MPEG comb-shaped copolymer for heat transfer applications

Iranian Polymer Journal - In this work, the effect of poly(styrene-co-maleic anhydride)-grafted methoxy (polyethylene glycol) (SMA-g-MPEG) copolymer as dispersants on the viscosity and thermal...     

Epichlorohydrin cross-linked β-cyclodextrin: an environmental method for the synthesis of 2-arylbenzothiazoles derivatives in water

In the present study, we report an environmentally benign synthesis of 2-arylbenzothiazoles derivatives from o-aminothiophenol and aldehydes in aqueous medium using β-cyclodextrin polymer as a catalyst and air as an oxidant. The polymer showed excellent catalytic activity, recovered, reused six times, and the catalyst efficiency remained unchanged. This suggests that the catalyst is an efficient and green catalyst for the synthesis of 2-arylbenzothiazoles derivatives and the obtained results could be promising for industrial synthesis of 2-arylbenzothiazoles derivatives.     

Synthesis of citric acid modified β-cyclodextrin/activated carbon hybrid composite and their adsorption properties toward methylene blue

In this article, citric acid modified β-cyclodextrin/activated carbon hybrid (CA-β-CD/AC) composites were synthesized by crosslinking reaction, and their adsorption properties for methylene blue were studied. The scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) method were used to characterize the structure and the morphology of composite materials. It was investigated that the effect of experiment parameters on the adsorption performance including weight fraction of AC in the composite, the adsorbent dose, the initial concentration of MB, the solution pH value, contact time, and temperature. The maximum adsorption capacity calculated by the Langmuir isotherm is 862.07 mg g⁻¹. Kinetic studies show that the adsorption process follows the pseudo-first-order and pseud-second-order reaction models. Thermodynamic analysis indicated that the adsorption behavior was an exothermic reaction. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48315.     

Selective adsorption of L-TA/D-TA by β-cyclodextrin derivative modified with l-tryptophan: Isotherm,kinetic and thermodynamics studies

β-Cyclodextrin derivative modified with l-tryptophan (L-Trp-CD) was prepared for recognitive chiral separation of tartaric acid enantiomers from ethanol solution. Kinetic properties were successfully investigated by pseudo-first-order model and pseudo-second-order model. Equilibrium data were described by the Langmuir and Freundlich isotherm models. The thermodynamics parameters (positive values of ΔH° and ΔS°, negative values of ΔG°) indicated that binding system for L-Trp-CD was endothermic, entropy gained and spontaneous. Selective adsorption result of l-tartaric acid (L-TA)/d-tartaric acid (D-TA) by L-Trp-CD indicated that L-Trp-CD has significantly higher adsorption capacity for L-TA compared with D-TA, and the selectivity coefficient is 3.36.     

Chemical Removal of CeO2 Segregated on the Surface of CeO2–ZrO2 Binary Oxides for Improvement of OSC

A chemical treatment to remove residual CeO₂ phase on CeO₂–ZrO₂ (CZ) solid solution was carried out. A CZ was treated by H₂O₂ for the reduction of Ce⁴⁺ to Ce³⁺ and then HNO₃ for the dissolution of Ce³⁺ compounds (H–CZ). H₂-TPR, TEM-EDX and XPS analyses revealed the removal of CeO₂ phase and the homogeneous distribution of Ce species. About 20% improvement in oxygen storage capacity (OSC) of H–CZ was confirmed at 773 K by the weight measurements under H₂/N₂ and air atmospheres, indicating that the HNO₃/H₂O₂ treatment was effective to avoid the deterioration of the OSC by segregated CeO₂ on the CZ binary oxides.     

Development and evaluation of Al2O3–ZrO2 composite processed by digital light 3D printing

Digital Light Processing (DLP) is a promising approach to fabricate delicate ceramic components with high-fidelity structural features. In this work, the alumina and zirconia/alumina ceramic suspensions with low viscosity and high solid loading (40 vol%) were prepared specifically for DLP 3D printing. After debinding and sintering, the final parts were obtained without any defects. The surface morphologies and mechanical properties of alumina (Al₂O₃) and zirconia toughened alumina (ZTA) composites were investigated and the results showed that the final parts exhibited high relative densities and good interlayer combination at the sintering temperature of 1600 °C. Comparing with the Al₂O₃, the ZTA composites exhibited significantly enhanced density (99.4%), bending strength (516.7 MPa) and indentation fracture toughness (7.76 MPa m^1/2).     

Pore formation model for direct laser deposition of Al2O3–ZrO2 ceramic

Pores are some of the most common defects that form during direct laser deposition of ceramic materials. A mathematical model of pore formation for Al₂O₃-ZrO₂ ceramic was developed. The pore formation model, which was developed from the bubble escape factor, reveals the relationship between the movement of the solid-liquid interface of the molten pool and that of the bubbles. In the frontier region of the molten pool, with increasing laser power, the proportion of bubbles that escaped and the area from which bubbles escaped increased. With increasing laser power, the actual and theoretical porosity decreased from 80 % to 40 %. At the central region of the molten pool, the bubble escape factor increased with increasing bubble diameter under the same laser power. The theoretical porosity and the actual porosity decreased with increasing laser power. The pore formation model provides a basis for fabricating high-quality Al₂O₃-ZrO₂ ceramics by direct laser deposition.     

Thermochemistry of the ZrO2–SrO System: From enthalpies of formation and heat capacities of the compounds to the phase diagram

The thermodynamics of the ZrO₂–SrO system is of interest for the optimization of synthesis and applications of functional materials and high-temperature structural ceramics. Earlier data on phase relationships and thermodynamic properties of the system are unfortunately scattered and inconsistent. In this study, the compounds Sr_n+1Zr_nO_3n+1 (n = 3, 2, and 1) were prepared by solid-state reaction. Their heat capacities from 573 to 1273 K were measured by differential scanning calorimetry and their enthalpies of formation from component oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. The CALPHAD method was used to assess the ZrO₂–SrO system, using both available literature data and our new measurements. A self-consistent thermodynamic database and the calculated phase diagram of the ZrO₂–SrO system are provided. This work is a prerequisite for accurate predictions of the relationships among the composition, temperature, and microstructure of complex functional and structural materials containing ZrO₂ and SrO.     

SO4–ZrO2 catalysts for the esterification of benzoic acid to methylbenzoate

SO₄–ZrO₂ catalysts, prepared by varying the conditions of oxide preparation and H₂SO₄ impregnation, have been characterized by means of different techniques (XRD, BET, Hammett–Bertolacini technique, XPS). The esterification of benzoic acid to methylbenzoate has been used to test the different catalysts and their catalytic performance has been discussed in the light of their bulk and surface properties. This revised version was published online in July 2006 with corrections to the Cover Date.