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Aromatic Polyamides (aromatic + polyamide)

Distribution by Scientific Domains

Polymers and Materials Science	94%

Selected Abstracts

Synthesis, static, and dynamic light scattering studies of soluble aromatic polyamide

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2008
Sonia Zulfiqar
Abstract Aromatic polyamide was synthesized via condensation polymerization of 4-aminophenyl sulfone (APS) with isophthaloyl chloride (IPC) using N,N -dimethyl acetamide (DMAc) as a solvent under anhydrous conditions. The purified aramid was studied by laser light scattering (LLS) in dimethyl sulfoxide (DMSO), a thermodynamically good solvent at 20°C. Static and dynamic light scattering studies permitted to determine the weight average molecular weight , radius of gyration , second virial coefficient A2, the hydrodynamic radius RH, and the diffusion coefficient D. Light scattering experiments were conducted at five concentrations ranging from 0.27 to 2.5,g/L. LLS measurement is also a very useful technique to study the aggregation or association in a polymer system as long as the large "clusters" are reasonably stable in time. The intensity autocorrelation function obtained on the quasi-elastically scattered light showed a simple diffusive relaxation mode. The ratio of radius of gyration to the hydrodynamic radius, i.e. ,,,1.3 indicates that the polyamide chain has coil conformation in DMSO at 20°C. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Predictive membrane transport model for nanofiltration processes in water treatment

AICHE JOURNAL, Issue 6 2001
Shih-Chieh Tu
A membrane transport model was developed for prediction and simulation of membrane filtration (nanofiltration) dynamics with reference to permeate flux. It incorporates important phenomenological aspects of membrane transport, such as concentration polarization and gel layer formation, and illustrates the concentration of solutes as foulants in the mass-transfer boundary layer on the membrane surface. Membrane filtration tests using tannic acid as a model organic compound were designed for investigating permeate fluxes, as well as solute concentration profiles for permeates and concentrates. Membrane performance experiments were conducted under various operation conditions by varying several parameters including solute concentrations, transmembrane pressures, and reject flow rates. The tests showed that the NF-45 membrane composed of polypiperazine amide was more susceptible to organic fouling by tannic acid than the NF-70 membrane made of cross-linked aromatic polyamide. These observations were supported by surface-potential measurements that demonstrated higher negative surface charges and greater hydrophilicity for the NF-70 membrane in the presence of tannic acid. The predictive capability of the membrane transport model was evaluated using the results from membrane filtration tests. Model sensitivity studies were conducted to obtain information on effects of various input parameters pertaining to operating conditions and fluid-dynamic regimes. [source]

Synthesis of a novel block copolymer containing aromatic polyamide and fluoroethylene segments

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2003
Arata Korematsu
A novel block copolymer containing aromatic polyamide (aramid) and fluoroethylene segments was synthesized by a two-step, low-temperature solution polycondensation. In the first step, a telechelic diamine was prepared by the reaction of 3,4,-diaminodiphenylether and tetrafluorosuccinic acid in the presence of 1,3-dicyclohexylcarbodiimide as a condensing agent. Next, the block copolymer was synthesized by the polycondensation of the telechelic diamine and isophthaloyl chloride. The number-average molecular weight of this polymer, according to gel permeation chromatography, was over 1.7 × 104. Incorporating fluoroethylene segments improved the solubility of the resulting polymer with respect to conventional aramids. [source]

Synthesis, static, and dynamic light scattering studies of soluble aromatic polyamide

New sets of solubility parameters of linear and crosslinked aromatic polyamides

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Stefano Fiori
Abstract As generally accepted, also in the case of polyamides linear and crosslinked polymeric materials are believed to be characterized by the same solution properties and, consequently, by the same solubility parameters. However, despite their great practical importance, a thorough study aimed to determine the best solvent media able to dissolve linear aromatic polyamides has not been performed yet or, at least, has not been published. In this study, we report on our study on the solubility parameters of linear and crosslinked aromatic polyamides. We demonstrate that the assumption of considering these two classes as having the same solubility properties can lead to dramatically erroneous results. Two new different sets for linear and crosslinked aromatic polyamides are proposed. Namely, linear poly(p -phenylene terephthalamide) is characterized by ,p, ,d, and ,H equal to 8.6, 18.4, and 11.3, respectively; by contrast, the corresponding values of the crosslinked aromatic polyamides taken into consideration are: 11.5, 16.8, and 10.2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Synthesis and characterization of dendronized aromatic polyamides with bromomethyl groups in the periphery

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Yanru Miao
Abstract This paper focused on the synthesis of novel functionalized dendronized aromatic polyamides, which contained a polyamide backbone and polyamide dendrons decorated with bromomethyl groups, by the macromonomer route. The new activating procedure of the synthesis of dendrons and macromonomers using thionyl chloride as an activating agent eliminated the protection/deprotection procedure and reduced side reactions. The structures of the dendrons, macromonomers, and polyamides were confirmed by FTIR, 1H NMR, 13C NMR, and elemental analysis. The properties of the resulting dendronized polyamides, which were compared with that of the linear polyamide (LP), were studied using GPC, XRD, TGA, DSC, inherent viscosity measurement, and solubility experiment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Synthesis, photoluminescence, and electrochromic properties of wholly aromatic polyamides bearing naphthylamine chromophores

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2006
Guey-Sheng Liou
Abstract A series of novel polyamides with pendent naphthylamine units having inherent viscosities of 0.15,1.02 dL/g were prepared via direct phosphorylation polycondensation from various diamines and a naphthylamine-based aromatic dicarboxylic acid, 1-[N,N -di(4-carboxyphenyl)amino]naphthalene. These amorphous polyamides were readily soluble in various organic solvents and could be cast into transparent and tough films. The aromatic polyamides had useful levels of thermal stability associated with high glass-transition temperatures (268,355 °C), 10% weight loss temperatures in excess of 480 °C, and char yields at 800 °C in nitrogen higher than 60%. These polymers showed maximum ultraviolet,visible absorption at 350,358 nm and exhibited fluorescence emission maxima around 435,458 nm in N -methyl-2-pyrrolidinone solutions with fluorescence quantum yields ranging from 0.4 to 15.0%. The hole-transporting and electrochromic properties were examined with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the polyamide films cast onto an indium tin oxide coated glass substrate exhibited one oxidative redox couple around 1.08,1.16 V (oxidation onset potential) versus Ag/AgCl in an acetonitrile solution and revealed good stability of the electrochromic characteristics, with a color change from colorless to green at applied potentials ranging from 0 to 1.6 V. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6094,6102, 2006 [source]

Novel aromatic polyamides and polyimides functionalized with 4- tert -butyltriphenylamine groups

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2006
Sheng-Huei Hsiao
Abstract A new triphenylamine-containing diamine monomer, 4,4,-diamino-4,- tert -butyltriphenylamine, was successfully synthesized by the cesium fluoride-mediated N,N -diarylation of 4- tert -butylaniline with 4-fluoronitrobenzene, followed by the reduction of the nitro group. The obtained diamine monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce two series of novel triphenylamine-based polyamides and polyimides with pendent tert -butyl substituents. Most of the polymers were readily soluble in polar organic solvents, such as N -methyl-2-pyrrolidone and N,N -dimethylacetamide (DMAc), and could be solution cast into tough and flexible polymer films. These polymers showed high glass transition temperatures between 282 and 320 °C, and they were fairly stable up to a temperature above 450 °C (for polyamides) or 500 °C (for polyimides). These polymers exhibited UV absorption maxima around 308 to 361 nm. The photoluminescence spectra of the polyamides in DMAc exhibited a peak emission wavelength in the blue at 421,433 nm. Cyclic voltammograms of polyamides and polyimides showed an oxidation wave at 1.0,1.1 V versus Ag/AgCl in an acetonitrile solution. All the polyamides and polyimides exhibited excellent reversibility of electrochromic characteristics by continuous several cyclic scans between 0.0 and 1.1,1.3 V, with a color change from the original pale yellowish neutral form to the green or blue oxidized forms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4579,4592, 2006 [source]

Synthesis and characterization of new polyamides based on Diphenylaminoisosorbide

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2005
Asmaa A. Caouthar
Abstract New aromatic polyamides were synthesized by the microwave-assisted polycondensation of an optically active isosorbide-derived diamine with different diacyl chlorides in the presence of a small amount of N -methylpyrrolidinone. Polymers with inherent viscosities between 0.22 and 0.73 dL/g were obtained corresponding to molecular weights up to 140,000 g/mol. With interfacial polymerization or the Higashi method, lower molecular weight polymers were obtained with inherent viscosities in the range of 0.04,0.36 dL/g. Differential scanning calorimetry measurements clearly demonstrated the high thermal stability of these polymers (mp = 180,300 °C) and the absence of decomposition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6480,6491, 2005 [source]

Novel family of triphenylamine-containing, hole-transporting, amorphous, aromatic polyamides with stable electrochromic properties

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2005
Tzy-Hsiang Su
Abstract We report the preparation and characterization of a series of novel electrochromic, aromatic poly(amine amide)s with pendent triphenylamine units. The synthesis proceeded via direct phosphorylation polycondensation between a novel diamine, N,N -bis(4-aminophenyl)- N,,N,-diphenyl-1,4-phenylenediamine, and various aromatic dicarboxylic acids. All the poly(amine amide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability and 10% weight-loss temperatures above 540 °C. Their glass-transition temperatures were 263,290 °C. These polymers in N -methyl-2-pyrrolidinone solutions exhibited strong ultraviolet,visible absorption peaks at 307,358 nm and photoluminescence peaks around 532,590 nm in the green region. The hole-transporting and electrochromic properties were studied with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of poly(amine amide) films prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidation redox couples at 0.65 and 1.03 V versus Ag/AgCl in an acetonitrile solution. All the poly(amine amide)s showed excellent stability with respect to their electrochromic characteristics; the color of the films changed from pale yellow to green and then blue at 0.85 and 1.25 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2085,2098, 2005 [source]

Synthesis and properties of novel soluble polyamides having ether linkages and laterally attached p -terphenyl units

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2004
Sheng-Huei Hsiao
Abstract A new ether-bridged aromatic dicarboxylic acid, 2,,5,-bis(4-carboxyphenoxy)- p -terphenyl (3), was synthesized by the aromatic fluoro-displacement reaction of p -fluorobenzonitrile with 2,,5,-dihydroxy- p -terphenyl in the presence of potassium carbonate, followed by alkaline hydrolysis. A set of new aromatic polyamides containing ether and laterally attached p -terphenyl units was synthesized by the direct phosphorylation polycondensation of diacid 3 with various aromatic diamines. The polymers were produced with high yields and moderately high inherent viscosities (0.44,0.79 dL/g). The polyamides derived from 3 and rigid diamines, such as p -phenylenediamine and benzidine, and a structurally analogous diamine, 2,,5,-bis(4-aminophenoxy)- p -terphenyl, were semicrystalline and insoluble in organic solvents. The other polyamides were amorphous and organosoluble and could afford flexible and tough films via solution casting. These films exhibited good mechanical properties, with tensile strengths of 91,108 MPa, elongations to break of 6,17%, and initial moduli of 1.95,2.43 GPa. These polyamides showed glass-transition temperatures between 193 and 252 °C. Most of the polymers did not show significant weight loss before 450 °C, as revealed by thermogravimetric analysis in nitrogen or in air. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4056,4062, 2004 [source]

Synthesis and characterization of aromatic polyamides containing alkylphthalimido pendent groups

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002
E. Ferrero
Abstract A series of polyisophthalamides containing pendent phthalimido groups and flexible side spacers were prepared from four novel diacids and three commercial aromatic diamines. These polyamides were prepared in high yields and with high molecular weights by direct polycondensation with triphenyl phosphite and pyridine as condensing agents. The weight-average and number-average molecular weights, measured by gel permeation chromatography, were 70,000,137,000 and 47,000,86,000 g/mol, respectively. The novel polyamides were amorphous and readily soluble and showed glass-transition temperatures of 150,240 °C, as measured by differential scanning calorimetry. Thermogravimetric analysis showed that the 10% weight-loss temperatures in nitrogen were 355,430 °C, a significant improvement in thermal stability having been observed with the increase in the side-chain length. A theoretical quantum mechanical study was successfully carried out to explain these results. Flexible and tough films, cast from polymer solutions, showed tensile strengths of 50,125 MPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3711,3724, 2002 [source]

Synthesis and characterization of novel soluble triphenylamine-containing aromatic polyamides based on N,N,-bis(4-aminophenyl)- N,N,-diphenyl-1,4-phenylenediamine

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2002
Guey-Sheng Liou
Abstract A new triphenylamine-containing aromatic diamine, N, N,-bis(4-aminophenyl)- N, N,-diphenyl-1,4-phenylenediamine, was prepared by the condensation of N,N,-diphenyl-1,4-phenylenediamine with 4-fluoronitrobenzene, followed by catalytic reduction. A series of novel aromatic polyamides with triphenylamine units were prepared from the diamine and various aromatic dicarboxylic acids or their diacid chlorides via the direct phosphorylation polycondensation or low-temperature solution polycondensation. All the polyamides were amorphous and readily soluble in many organic solvents such as N, N -dimethylacetamide and N -methyl-2-pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (257,287 °C), 10% weight-loss temperatures in excess of 550 °C, and char yields at 800 °C in nitrogen higher than 72%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2810,2818, 2002 [source]

Synthesis of well-defined poly(p -benzamide) from chain-growth polycondensation and its application to block copolymers

MACROMOLECULAR SYMPOSIA, Issue 1 2003
Tsutomu Yokozawa
Abstract Poly(p -benzamide) with a defined molecular weight and a low polydispersity and block copolymers containing this well-defined aramide was synthesized. Phenyl 4-(4-octyloxybenzylamino)benzoate (1b) polymerized at room temperature in the presence of base and phenyl 4-nitrobenzoate (2a) as an initiator in a chain-growth polycondensation manner to give well-defined aromatic polyamides having the 4-octyloxybenzyl groups as a protecting group on nitrogen in an amide. It was confirmed by a model reaction that deprotection of this protecting group proceeded completely with trifluoroacetic acid (TFA) without breaking the amide linkage. The utility of this approach to poly(p -benzamide) with a low polydispersity was demonstrated by the synthesis of block copolymers of poly(p -benzamide) and poly(N -octyl- p -benzamide) or poly(ethylene glycol). The SEM images of the supramolecular assemblies of the former block copolymer showed ,m-sized bundles and aggregates of flake structures. [source]