Structure–rheology relationship in complex quaternized polysulfones/solvent/nonsolvent systems

Polymer chains consisting of water-soluble polysulfones with various amounts of ionic chlorine have been prepared via the quaternization reaction of chloromethylated polysulfones with N,N-dimethylethanolamine. Rheological investigations have reflected the importance of electrostatic interactions, hydrogen bonding, and association phenomena from the ternary systems consisting of a proton-acceptor polymer (polysulfones with different ionic chlorine content), a proton-donor solvent (N,N-dimethylformamide), and a proton-donor solvent (methanol). The specific interactions, the polyelectrolyte effect induced by enhanced dissociation of the ionizable groups and mixed solvents’ quality modify the rheological functions, i.e., dynamic viscosity, elastic shear modulus and viscous shear modulus, as well as the thermodynamic parameters obtained from the rheological properties, such as apparent energy of activation and flow activation entropy. These results were correlated with the surface properties of the polysulfonic films formed from solutions in solvent/nonsolvent mixtures.     

Turbidimetric and intrinsic viscosity study of EVA copolymer–solvent systems

Both Hansen solubility parameter and Flory–Huggins interaction parameter of two EVA [Poly(ethylene-co-vinyl acetate)] copolymers with different vinyl acetate content have been obtained by means of intrinsic viscosity measurements. To calculate this last parameter it was also necessary to determine the theta solvent at different temperatures of the two EVA copolymers with turbidimetric measurements. The results indicate that the vinyl acetate content is a variable which influences the composition of the theta solvent and Flory–Huggins parameter (the higher the vinyl acetate content, the lower the Flory–Huggins parameter), although its influence over the Hansen solubility parameter is almost negligible.     

Exploring the filler–polymer interaction and solvent transport behavior of nanocomposites derived from reduced graphene oxide and polychloroprene rubber

Aliphatic solvent resistance of polychloroprene rubber (CR) reinforced reduced graphene oxide (RGO) nanocomposites were explored in the temperature range of 30–50 °C using hexane, heptane, and octane. Microstructure-assisted solvent resistant property is evident from transmission electron microscopy images of fabricated composites. Different transport parameters such as diffusion, permeation, and sorption constants were moderate while increasing RGO content. Diffusion mechanism was explained based on the permeating molecule and is found to be close to Fickian mechanism except for heptane. Evaluation of kinetic and thermodynamic parameters shows the ability of nanoreinforcement to alter thermodynamic characteristics and rate constant values. The extent of reinforcement was also evaluated by Kraus equation. From swelling studies, molecular mass between crosslinks was evaluated using Flory–Rehner equation and compared these values with theoretical predictions such as phantom and affine models to analyze the deformation and mobility of the network during swelling. Temperature plays a significant role in the transport of organic solvent through CR/RGO nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48168.     

Simultaneous spectrophotometric determination of manganese,zinc and cobalt by kernel partial least–squares method

Simultaneous spectrophotometric determination of Mn, Zn and Co was studied by two methods, classical partial least-squares (PLS) and kernel partial least-squares (KPLS), with 2-(5-bromo-2- pyridylazo)-5-diethylaminephenol (5-Br-PADAP) and cetyl pyridinium bromide (CPB). Two programs, SPGRPLS and SPGRKPLS, were designed to perform the calculations. Eight error functions were calculated for deducing the number of factors. Data reductions were performed using principle component analysis. The KPLS method was applied for the rapid determination from a data matrix with many wavelengths and fewer numbers of samples. The relative standard errors of prediction (RSEP) for all components with KPLS and PLS methods were the same (0.0247). Experimental results showed both methods to be successful even where there was severe overlap of spectra.     

Preparation and properties of high viscosity and elasticity asphalt by styrene–butadiene–styrene/polyurethane prepolymer composite modification

The porous asphalt pavements is often used in important occasion for its special properties and performance which can be to a great extent attributed to the binder—high viscosity and elasticity asphalt (HVEA). To prepare high demanding binder for porous asphalt pavements, the polyurethane prepolymer (PUP) and styrene–butadiene–styrene (SBS) were used to modify the matrix asphalt compositely. First, based on a series of physical tests, the effects of binder composition on performance of SBS/PUP HVEA binder (SBS/PUP-HVEA) were investigated. Then the Fourier transform infrared (FTIR) test was conducted to investigate the reaction mechanism of SBS/PUP-HVEA binder. Last, the fluorescence microscopy, stability tests, multiple stress creep recovery test, and differential scanning calorimetry test were carried out to evaluate and compare the phase structure, storage, high-temperature performance, thermostability characteristics of several HVEA binders. It is found that the composite modification of SBS and PUP can produce high quality binder which possesses high viscosity and high elasticity. And the composition of SBS/PUP-HVEA were recommended as follows: Shell-70# can be chosen as matrix asphalt, the contents of SBS modifier (SBS1301:SBS4303 = 1:2), H2122A PUP, chain extender M-OEA, and crosslinker sulfur were suggested 4%, 5%, 0.5%, and 1‰, respectively. The new functional groups observed in FTIR confirmed the existence of physical and chemical reactions in the modification process, which were beneficial to improve the high temperature performance and storage stability of the binder. SBS/PUP-HVEA had good phase structure, storage stability, high temperature performance, and thermostability compared to other HVEA binders. This study demonstrated that the SBS/PUP compositely modified asphalt possessed high viscosity and high elasticity, which can be used in the porous asphalt mixture and other highly demanding working environment as well.     

Study on interfacial interaction energy of Cu–SAM–epoxy systems in a hot and humid environment

Due to poor adhesion, the interfacial delamination is one of the typical failure modes in electronic packages. In this paper, two kinds of self-assembly monolayers (SAMs), SAMA and SAME, are added to Cu–epoxy interface and the effects of temperature, moisture, and cross-link conversion on the modified interfaces are investigated with molecular dynamics (MD) simulation. The results show that the interfacial interaction energy of the systems with SAMA increases with the increasing temperature, decreasing moisture content, and cross-link conversion. However, the interfacial interaction energy of the systems with SAME decreases with the increasing temperature and moisture content, while it is reluctant to the cross-link conversion. In addition, the simulation reveals that the covalent bonds between SAMA and epoxy enhance the interfacial adhesion of Cu–epoxy. However, the nonbond interactions of SAME and epoxy resin weaken the interfacial adhesion. This paper provides a new method for research and valuation the effects of SAM or other adhesive on interfacial adhesion. MD simulation is an efficient tool in predicting the performances of materials.     

Simultaneous determination of chlorine and oxygen evolving at RuO2/Ti and RuO2–TiO2/Ti anodes by differential electrochemical mass spectroscopy

Chlorine and oxygen evolving at RuO2/Ti and RuO2–TiO2/Ti anodes have been simultaneously determined at electrode potentials from 1.0 to about 2V (vs Ag/AgCl) by differential electrochemical mass spectroscopy (DEMS). On the RuO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with a decrease in RuO2 loading, while the chlorine evolution potential was unchanged. Low RuO2 loading anodes gave a high chlorine evolution ratio under various constant electrolysis potentials. On the RuO2–TiO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with an increase in the TiO2 content more remarkably than that for chlorine evolution. High TiO2 content anodes gave a high chlorine evolution ratio at various constant electrolysis potentials. The combination of RuO2 and TiO2 exhibits a remarkable effect with respect to the enhancement of chlorine evolution selectivity.     

Simultaneous determination of RRR- and SRR-α-tocopherols and their quinones in rat plasma and tissues by using chiral high-performance liquid chromatography

We established a method to simultaneously determine RRR- and SRR-α-tocopherol (α-Toc) and their quinones in biological samples by chiral-phase high-performance liquid chromatography (HPLC). α-Toc had a shorter retention time than α-tocopherylquinones (α-TQ), and 2-ambo-α-Toc was completely separated into two peaks; the first peak was RRR-α-Toc and the second SRR-isomer by chiral HPLC connected Chiralcel OD-H column and Sumichiral OA4100 column. In contrast, of the two peaks of α-TQ, the first was the SRR-isomer. We also investigated differences in the distribution of RRR- and SRR-α-TQ in rat tissues after oral administration of 2-ambo-α-Toc by the above HPLC method. Rats deficient in vitamin E were divided into two groups, control and experimental, and tissues were collected at 3, 6, and 24 h after oral 2-ambo-α-Toc administration. The concentrations of RRR- and SRR-α-Toc and their quinones in plasma and each tissue were determined. The concentration of SRR-α-TQ in plasma and adrenal glands was not significantly different from RRR-α-TQ. However, the concentration of SRR-α-TQ in liver up to 6 h after oral administration was higher than that of RRR-α-TQ, and SRR- and RRR-α-TQ levels were similar at 24 h after oral administration. Therefore, we may assume that the formation of α-TQ in vivo was not different between RRR- and SRR-isomer and that it was not affected by the presence of α-Toc stereoisomers.     

Synthesis of polymer–silica hybrid polyHIPEs by double in situ polymerization of concentrated water in oil emulsion

Highly porous monoliths from polymerized high internal phase emulsions (polyHIPEs) are proposed for a number of applications including liquid absorbents, biocatalysis, tissue engineering, bioseparation etc. To overcome some limitations of fully organic polyHIPEs hybrid organic–inorganic templated porous polymers are particular attractive. Here we present a straightforward protocol towards hybrid polyHIPEs by combining fast photo polymerization of the organic HIPE with in-situ polycondensation of tetraethylorthosilicate (TEOS). While under acidic conditions TEOS polymerization leads to a more bicontinous structure, true double-layered morphologies were obtained under basic conditions as evident from SEM imaging, mercury intrusion porosimetry and nitrogen physisorption measurements. Moreover, chemical amine functionalization of the silica network surface of the hybrid polyHIPEs was demonstrated using a silane coupling agent and subsequent visualization by reaction with fluorescein isothiocyanate (FITC).     

Changes in morphology and properties of NR–NBR blends. Effect of viscosity ratio modified by liquid natural rubber and epoxidised liquid natural rubber

Abstract

Changes in rheological properties, morphology, and oil resistance in NR–NBR blends by viscosity ratio have been investigated. In this study, the viscosity ratio was modified by mechanical mastication and addition of liquid natural rubber (LNR) and epoxidised liquid natural rubber (ELNR). The results reveal that as viscosity ratio increased from 0·5 to 1·0, Mooney viscosity of the blends increased, and then decreased sharply as the viscosity ratio further increased from 1·0 to 2·0. The addition of LNR and ELNR for plasticising NR and NBR, respectively, does not significantly affect cure properties of the blends. The phase size of the NR dispersed phase depends strongly on the viscosity ratio. The high viscosity of the matrix and/or the low viscosity of the dispersed phase promote breaking up of the dispersed phase. Unexpectedly, a decrease in size of the dispersed phase by the modification of viscosity ratio via the use of low molecular weight rubber (i.e. LNR and ELNR) did not result in an improvement in oil resistance.     

Homo- and mixed polymer brushes prepared by surface-grafting of asymmetric non-sticky/sticky diblock copolymers and their stimuli–responsive behaviors

We synthesize a non-sticky/sticky diblock copolymer, poly[styrene-b-3-(trimethoxysilyl)propylmethacrylate], to produce polymer brushes using the grafting-to technique. Uniform coatings of the polymer brushes are efficiently produced because of the multiple reactive groups offered by the sticky block, and the surface coverage and nanoscopic morphology of the brush layer are adjusted by varying the concentrations of the immersion polymer solutions and the immersion time of the substrate. The nanoscopic pattern of the polymer brushes is subsequently utilized to produce mixed polymer brushes. The resulting homo- or mixed polymer brushes change their nanoscopic morphology in response to external stimuli of temperature and solvent. The results indicate that grafting of the asymmetric non-sticky/sticky block copolymer is an efficient method for producing a surface of polymer brushes with nanoscopic chemical heterogeneity.     

Flotation-assisted homogeneous liquid–liquid microextraction for determination of thorium in water samples by inductively coupled plasma–mass spectrometry and Box–Behnken design

A fast, simple, and efficient method for extraction, preconcentration, and determination of thorium in water samples with acceptable recoveries based on flotation-assisted homogenous liquid–liquid microextraction combined with inductively coupled plasma–mass spectrometry (ICP-MS) is presented. Various parameters affecting the extraction efficiency were optimized by Box–Behnken design. Under the optimum conditions (concentration of dimethyl vinyl phosphonate = 2.4 × 10^–4 mol/L, pH = 6.5, n-heptane = 150 μL, and acetonitrile = 0.5 mL), the calibration graph was linear in the range of 10.0–400.0 ng/L for thorium. The limit of detection of this method was 2.62 ng/L, and the enrichment factor was estimated to be 136 for thorium.     

Simultaneous measurement of velocity profile and liquid film thickness in horizontal gas–liquid slug flow by using ultrasonic Doppler method

Horizontal gas–liquid two-phase flows widely exist in chemical engineering, oil/gas production and other important industrial processes. Slug flow pattern is the main form of horizontal gas–liquid flows and characterized by intermittent motion of film region and slug region. This work aims to develop the ultrasonic Doppler method to realize the simultaneous measurement of the velocity profile and liquid film thickness of slug flow. A single-frequency single-channel transducer is adopted in the d...     

Preparation and application of epoxy–chitosan/alginate support in the immobilization of microbial lipases by covalent attachment

The aim of this work was the preparation and application of highly hydrophobic epoxy–chitosan/alginate as a support to immobilize microbial lipases from Thermomyces lanuginosus commercially available as Lipolase® (TLL1) and Lipex® 100L (TLL2) and Pseudomonas fluorescens (PFL). The catalytic properties of the biocatalysts were assayed in olive oil hydrolysis and butyl butyrate synthesis. The results indicated that 12 h was enough for TLL1 to be immobilized on the support. Covalent attachment of TLL1 turned biocatalysts highly active and around 6-fold more stable than free lipase. Based on the results, a time of incubation of 24 h was selected for further studies about the maximum immobilized protein amount and butyl butyrate synthesis. Maximum protein loading immobilized was found to be 25.4 mg g^?1 support for TLL1, followed by TLL2 (20.5 mg g^?1) and PFL (15.5 mg g^?1) offering 80 mg protein g^?1 support. The immobilization of TLL1 and TLL2 resulted in highly active biocatalysts (around 1300 IU g^?1 gel), almost fivefold higher than PFL (272.4 IU g^?1 gel). In butyl butyrate synthesis, PFL showed similar activity to TLL1 and TLL2 derivatives, up to 60 mmol L^?1. The biocatalysts displayed high activity after five successive cycles, retaining around 95% of the initial activity.     

Density,viscosity and surface tension of high-silicate CaO–SiO2 and CaO–SiO2–Fe2O3 slags derived by aerodynamic levitation. The behavior of Fe3+ in high-silicate melts

Thermophysical data for liquid slag are required for the optimization and control of metallurgical processes. The density, surface tension and viscosity were measured by employing aerodynamic levitation under contactless conditions. The high-silicate slag (44 and 63 mass-% of SiO₂) of the CaO–SiO₂ and CaO–SiO₂–Fe₂O₃ systems (with 5 and 10 mass-% Fe₂O₃) was investigated under (80% Ar + 20% O₂) gas atmosphere. The temperature ranges were between 800 °C and 2000 °C for the density and 1500 °C–2000 °C for surface tension and viscosity measurements. The influence of the CaO/SiO₂ ratio on the investigated properties and the behavior of Fe³⁺ ions in high-silicate melts were examined. The density of the CaO–SiO₂ melt was lower than that of the CaO–SiO₂–Fe₂O₃ systems. The surface tension of all compositions tested decreased with temperature and showed compositional dependence. The viscosity measured was higher in the Fe₂O₃-containing slag. The Raman spectroscopy analyses confirmed the increase in the degree of polymerization with the addition of Fe₂O₃ for the silicate-rich slag. The formation of a complex anion of a ferric ion and contribution to the silicate network were assumed. The trends observed were related to the structural properties and different interionic bonding. Urbain's viscosity model and FactSage? 7.3 were applied for the assessment of the experimental data.     

Simultaneous synthesis and consolidation of nanostructured TaSi2–Si3N4 composite by pulsed current activated combustion

Dense nanostructured 4TaSi₂–Si₃N₄ composite was synthesized by pulsed current activated combustion synthesis (PCACS) method within 3 min in one step from mechanically activated powders of TaN and Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of a pulsed current and mechanical pressure. Highly dense 4TaSi₂–Si₃N₄ composite with relative density of up to 98% was produced under simultaneous application of a 60 MPa pressure and the pulsed current. The average grain size and mechanical properties (hardness and fracture toughness) of the composite were investigated.     

Influence of ammonium salt formation on the activity and selectivity of the 12-molybdophosphate heteropolyacid catalyst prepared by solid–solid interaction in the ammoxidation of 2-methylpyrazine

The ammonium salt of 12-molybdophosphoric acid has been prepared by the solid-state interaction of the ammonium salts of molybdenum and phosphorus. The catalysts obtained by pretreatment of the precursor at various temperatures, have been characterized by nitrogen adsorption, X-ray diffraction (XRD), Fourier-transformed infrared (FTIR) spectroscopy and temperature-programmed decomposition (TPD) of the catalysts. Ammoxidation of 2-methylpyrazine has been carried out on these catalysts. The amount of ammonium salt present in the catalyst has been correlated with the activity and selectivity of the catalysts.