Abstract  In this work composite hollow-fibers were prepared by dip-coating of commercial polypropylene (PP) with a thin layer of ethylene-chlorotrifluoroethylene copolymer (ECTFE). The employment of N-methyl pyrrolidone (NMP) as solvent improved the polymer processability favoring dip-coating at lower temperature (135 degrees C). Scanning electron microscopy (SEM) analyses showed that after dip-coating the PP support maintained its microstructure, whereas a thin coated layer of ECTFE on the external surface of the PP hollow-fiber was clearly distinguishable. Membrane characterization evidenced the effects of the concentration of ECTFE in the dope-solution and the time of dip-coating on the thickness of ECTFE layer and membrane properties (i.e., contact angle and pore size). ECTFE coating decreased the surface roughness reducing, as a consequence, the hydrophobicity of the membrane. Moreover, increasing the ECTFE concentration and dip-coating time enabled the preparation of a thicker layer of ECTFE with low and narrow pore size that negatively affected the water transport. On the basis of the superior chemical resistance of ECTFE, ECTFE/PP composite hollow fibers could be considered as very promising candidates to be employed in membrane processes involving harsh conditions.

Abstract  In preparation of polymeric gas separation membranes by phase inversion method, polymer concentration is one of the most important variables which can change membrane morphology and behavior. In this research, critical concentration of the polyetherimide (PEI) solutions in N-methyl-2-pyrrolidone (NMP) as a solvent was determined by viscometric method. The influence of temperature on critical concentration was studied. Three asymmetric PDMS/PEI membranes with different concentrations of PEI were prepared and characterized for H-2/CH4 separation. The results showed that the membranes with higher concentrations than critical concentration were more suitable for gas separation. In addition, the viscosity data were fitted by appropriate equations and the densities were satisfactorily correlated by a simple first-order polynomial with respect to temperature and the PEI mass fraction. The prepared membrane showed the selectivity of 26 for H-2/CH4 separation at 1 bar and 25 degrees C for pure gas and 24.8 for mixed gas. The influence of the pressure on the H-2 and CH4 permeance and the selectivity for a mixed binary gas showed that the permeance of both gases declined by pressure enhancement and the selectivity increased. (c) 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Abstract  Six new flame retardant and optically active poly(amide-imide)s (PAIs) containing phosphine oxide moiety in the main chain were synthesized by direct polycondensation reactions of six chiral N-trimellitylimido-L-amino acids with bis(3-amino phenyl) phenyl phosphine oxide in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenyl phosphite (TPP), calcium chloride (CaCl(2)) and pyridine (Py). The polymerization reactions produced a series of flame retardant and optically active PAIs with high yields and good inherent viscosities in the range of 0.43-0.71 dm(3).g(-1). The resulting polymers were fully characterized by means of FTIR and (1)H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation and solubility tests. The thermal properties and flame retardant behaviour of the PAIs were investigated using thermal gravimetric analyses the limiting oxygen index (LOI) tests. Data obtained by the thermal analyses revealed that the polymers showed good thermal stability and also high char yields, in the TGA data, and good LOI values indicating that PAIs have good flame retardant properties.

Abstract  Six new heat resistant and optically active poly(amide-imide)s 5a-f were prepared by the direct polycondensation reaction of N,N'-(4,4'-pyromellitoyl)-bis-L-phenyl acetic acid 3 with various different diamines 4a-f in a medium consisting of triphenyl phosphite, N-methyl-2-pyrrolidone, pyridine and calcium chloride. These polymers were obtained in high yields and had inherent viscosities between 0.35-0.50 dL/g. The resulting polymers were characterized by viscosity measurements, thermal gravimetric analysis (TGA and DTG), differential scanning calorimeter (DSC), solubility test, specific rotation, FT-IR and H-1 NMR spectroscopy. N,N'-(4,4'-pyromellitoyl)-bis-L-phenyl acetic acid 3 was prepared by an one-stop reaction of pyromellitic anhydride 1 with L-phenyl acetic acid 3 in acetic acid solution in quantitative yield.

Abstract  This paper reports the characterization of new synthesized chiral polymeric membranes, based on a cellulose acetate propionate polymer. The flux and permselective properties of the membrane were studied using 50 % ethanol solution of (R,S)-trans-stilbene oxide as feed solution. Scanning electron microscopy revealed the asymmetric structure of these membranes. The roughness of the surface was measured by atomic force microscopy. The resolution of over 97 % enantiomeric excess was achieved when the enantioselective membrane was prepared with 18 wt% cellulose acetate and 8 wt% cellulose acetate propionate in the casting solution of dimethyl formamide/N-methyl-2-pyrrolidone/acetone, at 20 A degrees C and 55 % humidity, and a water bath at 10 A degrees C for the gelation of the membrane. The operating pressure and the feed concentration of the trans-stilbene oxide were 275.57, 345.19, and 413.84 kPa and 2.6 mM, respectively.

Abstract  An attempt was made to separate non-polar components from the polar fractions in kerosene using modified environments including the addition of polar solvents and surfactants. The solvent extraction process was based on the formation of an emulsion liquid membrane (ELM) which facilitates the separation. It was demonstrated that even a complex hydrocarbon mixture could be separated by ELM techniques if a facilitating agent (N-methyl pyrrolidone, NMP) was used in conjunction with high HLB surfactants (Tween 80). Low HLB value surfactants acted against the separation of polar compounds but participated in separation of apolar compounds.

Abstract  Heat treatment of THF-insoluble, CS2-N-methyl-2-pyrrolidinone (NMP) mixed solvent (1:1 by volume) soluble fraction (TIMS) of the extract, which was obtained from the extraction of Zao Zhuang coal with the same mixed solvent at room temperature, was carried out in several organic solvents at 100-350-degrees-C under N2 atmosphere. Retrogressive reaction of TIMS, i.e., its conversion to the mixed solvent-insoluble fraction (MI), was observed in tetralin (TET), naphthalene (NAP), and 9,10-dihydrophenanthrene (DHP) at temperatures as low as 100 and 175-degrees-C, while MI formation at 175-degrees-C was suppressed by adding 9,10-dihydroanthracene (DHA) or 1,4,5,8,9,10-hexahydroanthracene (HHA), which are much stronger hydrogen donors than TET, NAP, or DHP. Moreover, by these treatments, the THF-soluble fraction (TS), the lighter fraction than TIMs, was formed from TIMS. The quantity of hydrogen transferred from the solvents to TIMS and/or TIMS moieties was found to be well correlated with the quantity of MI formed. By a similar heat treatment in DHA at 175-degrees-C, Zao Zhuang raw coal was found to undergo dissolution reactions, i.e., the increase of TS and the decrease of MI, compared with those originally existing in the raw coal. The mechanism of the MI formation and its suppression during the heat treatments of TIMS at low temperatures is discussed.

Abstract  Aluminum nitride (AlN) ceramics has been prepared by a modified non-aqueous gelcasting technique, and the ceramic slurries with low viscosity and high solid loading were obtained by using 1-methyl-2-pyrrolidinone as solvent and Solsperse 24,000 as dispersant. The rheological behaviors of the AlN ceramic slurry and the densities of AlN ceramics were studied. Typically, the AlN ceramic slurry (Solsperse 24,000 of 0.5 wt% and solid loading of 50 vol%) showed a viscosity of 0.09 Pa.s at shear rate of 100 s(-1). And more interestingly, when increasing solid loading to 55 vol%, the AlN slurry still kept a low viscosity of about 0.28 Pa.s, which was reduced by 30% compared to the reported values. As a result, the resultant green body exhibited a relative density of 65.5%, and a flexural strength of 42.3 MPa. After sintering at 1900 degrees C for 5 h, the AlN ceramics with an improved relative density of 99.4% was produced. Thus, this research would provide a new way to prepare low-viscosity and high solid-loading AlN slurry. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Abstract  By using water-miscible and water-immiscible solvents (N-methyl-2-pyrrolidone and methlyene chloride (MC)) in the casting solution to prepare poly(ether imide) (PEI) asymmetric membranes via a phase-inversion process, we have studied the flat membrane formation, membrane morphology, and gas separation performance in terms of PEI content, MC content, and standing time. In such a system, the immiscibility of MC with water plays a very important role in determining the final membrane morphology and performance. The influence of methylene chloride was shown in two aspects: (1) change of phase-inversion course and mechanisms; (2) post membrane structure change due to the interaction between PEI and methylene chloride. The silicone-coated PEI membranes exhibited a good membrane performance with O-2 permeance of (1.3-9.3) x 10(-6) cm(3)(STP)/cm(2). s . cmHg and O-2/N-2 selectivity of 5.2-6.4. It was found, from the gas permeation and membrane morphology studies, that the separation was mainly attributed to the cellular structures (closed cells) beneath the membrane surface skin.

Abstract  A new series of copoly(ether-amide-imide)s (CoPEAIs) 7a-f were synthesized through the direct polycondensation reaction of N,N'-(4,4'-diphenylether)bistrimellitimide 1 with 1,5-naphthalene diamine 2, 3,4-diamino benzophenone 3 in the presence of adipic acid 4, fumaric acid 5 and terephthalic acid 6 as a second diacid in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenyl phosphite (TPP), calcium chloride and pyridine (Py). The resulted polymers were fully characterized by means of Fourier transform infrared (FT-IR) spectroscopy, elemental analyses, inherent viscosity, solubility tests and ultraviolet-visible (UV-vis) spectroscopy. Thermal properties of the CoPEAIs 7a-c were evaluated with thermogravimetric analysis (TGA) techniques and derivative of thermogravimetric (DTG) under a nitrogen atmosphere. (C) 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Abstract  Two new samples of poly(amide-imide)montmorillonite reinforced nanocomposites containing N-trimellitimido moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 5 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N-trimellitimido-4-amino benzoic acid 3 with 4,4'-diamino diphenyl ether 4 in the presence of triphenyl phosphate (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nanocomposite films 5a and 5b with 10 and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposites films were investigated by using UV-vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements.

Abstract  A series of Poly(amide-imide)/montmorillonite nanocomposites containing N-pyromellitimido-L-phenyl alanine moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 5 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N-pyromellitimido-L-phenyl alanine 3 with 4,4'-diamino diphenyl ether 4 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PAI matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

Abstract  New optically active poly(ester-imide)s (PEIs) containing bicyclo[2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic diimide in the main chain were prepared by the reaction of N,N'-(bicyclo[2,2,2] oct-7-ene-2,3,5,6-tetra carboxylic)-bis-L-valine 4 as a diacid monomer with various aromatic diols 5a-g in a system of tosyl chloride (TsCl), pyridine (Py), and N,N-dimethylformamide (DMF). The reactions with TsCl were significantly promoted by controlling alcoholysis with diols, in the presence of catalytic amounts of DMF, to give a series of optically active poly(ester-imide) s. The resulting new polymers were obtained in good yields and inherent viscosities, ranging between 0.36 and 0.62 dL g(-1), and were characterized with FT-IR and (1)H-NMR spectroscopy, including specific rotation. All of these polymers were highly organosoluble at room temperature in solvents like N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and sulfuric acid. The thermal stability of the resulting PEIs was evaluated with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques under a nitrogen atmosphere, which indicated that the residual weight percent of the polymers at 600 degrees C was 43.69%-60.5% and showed that they are moderately thermally stable.

Abstract  In this article, thermally conductive and relatively low dielectric constant polymer matrix composites of an aluminum nitride filler (AlN) and a novel liquid crystalline copoly(ester amide) (LCP) were prepared via a solution blending method in the presence of a phosphate containing dispersant. The viscosities, thermal conductivities, and dielectric properties of the prepared AlN/LCP composites were investigated as a function of AlN loading. Our experimental results demonstrated that the AIN/LCP composite with AlN concentration of 50 wt% had 2.5 times higher thermal conductivity than pure LCP (2.020 and 0.817 W/mK for composite with 50 wt% of AlN and pure LCP, respectively), but its dielectric constant remained at low level, i.e., < 9.0 at frequency of 900 Hz. In addition, viscosities of AlN/LCP pastes in the N-methyl-2-pyrrolidinone solvent remained at acceptable levels with the high AlN loading of 50 wt%. The morphologies of the prepared composites were also investigated by scanning electron microscopy. POLYM. COMPOS., 2012. (C) 2012 Society of Plastics Engineers

Abstract  A variety of silicone fluids have been found to gel using low concentrations (typically <4 wt.%) of 1,3:2,4-dibenzylidene sorbitol (DBS). DBS is known to be a chiral gelator for many organic solvents. Gels were formed when small amounts of DBS were introduced into the silicone fluids either by heating to high temperatures or at ambient temperatures with the use of a co-solvent. Optical and electron microscopy of neat silicon-DBS gels (concentration as low as 0.005 wt.%), revealed the formation of two types of fibrous network. One consisted of ribbon-like macrofibres (average width, ca. 2-3 mu m) present in the opaque region of the gels and the other consisted of dense intertwined microfibres (average width, ca. 100 nm) present in the clear portion of the gels. The gels prepared in the presence of a co-solvent consisted only of the microfibrous network. N-Methylpyrrolidone was found to be a very effective co-solvent for the phenyl-containing siloxanes producing firm clear gels. Dynamic mechanical measurements indicated that the storage modulus (G') of these gels increased with increasing DBS content over the range 1-6 wt.% DBS. Comparison with propylene glycol-DBS gels showed the silicone gels to differ in that they comprised mostly an isotropic phase with no detectable crystalline phase present.

Abstract  Solubilities between 323.15 and 413.15 K and equilibrium data between 323.15 and 373.15 K for the water + 4-hydroxy-4-methyl-2-pentanone + benzyl alcohol ternary system are reported in order to obtain the extractive properties of benzyl alcohol for separating 4-hydroxy-4-methyl-2-pentanone from aqueous solutions, and the influence of temperature. Solubility data of the binary system water + benzyl alcohol are also reported. The effect of temperature on liquid-liquid phase equilibrium was determined, and its consequences are discussed. Tie-line data were satisfactorily correlated by the Othmer and Tobias method [Othmer, D.F, and Tobias, P.E., 1942. Tie line correlation. Ind. Eng. Chem., 34: 693-696]. The experimental data were compared with values calculated by the NRTL and UNIQUAC equations for the ternary mixture, and the predictions obtained by the UNIFAC method are also included. While the water + benzyl alcohol system has a binary upper critical solution temperature at 421.65 K, no ternary one was observed. It is concluded that benzyl alcohol is appropriate for the extraction process when the mass fraction of the consolute component in the extract phase is less than 0.22, not as suitable when this concentration is greater. The small difference in the extractive properties between 348.15 K and room temperature shows that it is unnecessary to carry out the extraction at a higher temperature.

Abstract  Atmospheric resid was treated with N-methylpyrrolidone in the presence of the undecane fraction at mass ratios to the feedstock of 3:1 and 0.5:1 with preliminary light deasphalting with and without pentane. As a result, the sulfur content in the atmospheric resid decrease by four times and the carbon residue decreases by two times. N-Methylpyrrolidone forms an azeotrope with undercane with a boiling point of 179 degrees C. i.e., 25 degrees lower than for the extracting agent. This allows decreasing the degree of its decomposition in regeneration and corrosion of the equipment.

Abstract  In this paper, a novel positively charged asymmetrical membrane was manufactured from brominated polyphenylene oxide (BPPO)/N-methyl-2-pyrrolidone (NMP)/H(2)O Via in situ amination with triethanolamine (TEOA) and a dry-wet phase inversion. The casting solution was exposed to the humid surroundings before immersing into the coagulation bath. The positive charge character of the membrane surface was examined by streaming potential and the effect of the evaporation time and the relative humidity (RH) on the membrane properties and microstructure were investigated, respectively. It was interestingly found that the role of evaporation time and the relative humidity on the membrane performance and morphologies for a positively charged casting system was different from the conventional rule. This was mainly due to the competition of two influence factors, i.e., evaporation of solvent and water absorption of the casting solution. The results were conformed to SEM observation and pore size distribution. Furthermore, the process of water absorption of the casting solution was monitored by attenuated total reflectance infrared (ATR-FTIR) spectroscopy technique. Additionally, in order to compare to the dry-wet phase inversion method, the membranes were obtained by prolonging the exposure time to more than 12 h (which was similar to vapor-induced phase inversion) at different RH. Polymer nodules on the membrane surface and a symmetrical morphology were observed by SEM. (C) 2008 Elsevier B.V. All rights reserved.

Abstract  Solvent extractions of two different types of Chinese rich coals i.e. Aiweiergou coal (AG) and Zaozhuang coal (ZZ) using the mixed solvent of carbon disulfide/N-methyl-2-pyrrolidinone (CS(2)/NMP) with different mixing ratios were carried out and the caking indexes of the extracted residues were measured. It was found that the extracted residues from the two types of coals showed different changing tendencies of the caking indexes with the extraction yield. When the extraction yield attained about 50% for ZZ coal, the extracted residue had no caking property. However for AG coal, when the extraction yield reached the maximum of 63.5%, the corresponding extracted residue still had considerable caking property with the caking index of 25. This difference indicated the different associative structure of the two coals although they are of the same coalification. Hydro-thermal treatment of the two rich coals gave different extract fractionation distributions for the treated coals compared to those of raw coals respectively. The coking property evaluations of the two coals and their hydro-thermally treated ones were carried out in a crucible coking determination. The results showed that the hydro-thermal treatment could greatly improve the micro-strengths of the resulting coke from the two coals, and the improvement was more significant for the more aggregated AG coal. The reactivities of hydro-thermally treated AG coal blends were almost the same as those of raw coal blends. The higher coke reactivities of AG raw coal and its hydro-thermally treated ones than those of ZZ coal might be attributed to its special ash composition. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  Effect of tetrabutylammonium acetate (TBAA) addition on the aggregation of coal-derived materials at solution and solid states was investigated. As coal-derived materials, a pyridine-insoluble fraction (PI) of the extract of Upper Freeport coal was used. Two kinds of the solid states with quite different solubility in N-methyl-2-pyrrolidinone (NMP) were obtained for PI by the removal of the solvents from its solution in NMP with and without TBAA, respectively. Similar results were obtained when CS2/NMP mixed solvent was used instead of NMP. Characterizations of these two types of PI by FT-IR, elementary, and XRD analysis suggest that they have different states of molecular aggregation, which seem to be the reflection of their aggregation states in solution.

Abstract  The roles of CS2 in the CS2/NMP mixed solvent to coal extraction and solubilization were investigated in this study. There was little effect of removing of CS2 from the solutions on the solubilities of UF coal extract and pyridine insoluble (PI) of the extract in the NMP/CS2 mixed solvent, suggesting that NMP has high enough solubilities to the UF coal extract and PI. Six Argonne different rank coals were extracted with the CS2/NMP mixed solvent and NMP, respectively. It was found that the extraction yield difference between NMP and CS2/NMP mixed solvent for UF coal is largely deviated from the curve obtained for the other 5 coals, suggesting that the pre-swelling of CS2 in the mixed solvent may be one of important roles for high extraction yield of UF coal in the CS2/NMP mixed solvent. FTIR indicated that there was a strong interaction between CS2 and NMP in the CS2/NMP mixed solvent of 1:1 volume ratio, which made the strong absorbance at 2156 cm(-1) in the FTIR spectra, and this interaction may disrupt the dipole based association of NMP thus making the CS2/NMP mixed solvent lower viscosity, to penetrate more quickly into the network structure of coal, resulting in the larger solvent partner (NMP) to enter and break the stronger coal-coal interactions. (C) 2005 Elsevier B.V. All rights reserved.

Abstract  This work is focused on synthesis and characterization of a polymer blend microfiltration membrane for separation of microbial cells from lactic acid fermentation broth in a continuous process. The membranes were prepared by blending hydrophilic cellulose diacetate (CA) polymer with hydrophobic polysulfone (PSF) polymer in wet phase inversion method. Polymers were blended in N-methyl-2-pyrrolidone (NMP) solvent (70 wt%) where polyethylene glycol was added as a pore former. The membranes were characterized in terms of morphology, porosity, flux and microbial separation capability. The best prepared membrane with PSF/CA weight ratio of 25/75 yielded a pure water flux of 1830 LMH (liter/m(2) h) and a fermentation broth flux of 1430 LMH at around 1.5 bar TMP (trans-membrane pressure). The membrane was successful in complete retention of microbial cells from the broth in a continuous crossflow membrane module integrated with the fermentor. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  In this work, non-coking coal was extracted using of organic solvent mixture of n-methyl-2-pyrrolidone (NMP) and ethylenediamine (EDA). The coal extraction experiments were carried out at different ratios of coal to organic solvent mixture for 1 h under total reflux conditions. The optimum conditions for solvent extraction were determined. Ceramic membrane in microfiltration range was used for recovery of organic solvent from coal organic solvent mixture. Characterization of the prepared inorganic membrane was done in terms of pore size distribution, membrane porosity and chemical stability. Membrane experiments were carried out in batch cell. The mixture of coal and organic solvent obtained after extraction process was passed through ceramic membrane and recovered organic solvent was reused further for extraction process. Same steps were repeated continuously three times. The fabricated ceramic membrane showed solvent recovery of 71%, 68% and 66%, respectively, for successively three stages. The information provided in this study will be helpful to the steel making industries where pure carbon is extracted from coal using energy intensive distillation process. The amount of solvent recovery is quite high in this membrane based technique and will improve the economy of the process in a large extent compared to the existing distillation process. (C) 2012 Elsevier B.V. All rights reserved.