<i>N</i>‐methylation of wholly aromatic polyamides for size‐exclusion chromatography

Mourey, Thomas H.; Guistina, R. A.; Bryan, T. G.; Thornbury, R. F.; Blevins, Richard W.; Perry, Robert J.; Turner, S. Richard

doi:10.1002/app.1992.070451113

Cited by 7 publications

(7 citation statements)

References 13 publications

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“…The molecular weights of the N‐butylated polymers were evaluated by GPC (Table ). For PPTA with an inherent viscosity of 7.49 dL/g, a number‐averaged molecular mass of 37,000 g/mol was estimated, which was comparable to the results obtained by Ying et al and Mourey et al…”

Section: Resultssupporting

confidence: 87%

“…The molecular weights of the N-butylated polymers were evaluated by GPC (Table 1). For PPTA with an inherent viscosity of 7.49 dL/g, a number-averaged molecular mass of 37,000 g/mol was estimated, which was comparable to the results obtained by Ying et al 46 and Mourey et al 47 CR Reaction of APPTA-x CR reactions of APPTA-x were carried out in NMP at 190 8C for 6 h. At the beginning, APPTA-x was suspended in NMP.…”

Section: Resultsmentioning

confidence: 92%

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Synthesis and properties of poly(p-phenylene terephthalamide) bearing both polar and unsaturated substituents introduced via claisen rearrangement reaction

Wang

Guan

et al. 2016

J. Polym. Sci. Part A: Polym. Chem.

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A series of novel wholly aromatic copolyamides, poly(p-phenylene terephthalamide)-ran-poly[p-phenylene 2,5-bis(allyloxy)terephthalamide] x (50,5,25, 50, 60, 75, 90, and 100) represents the molar fraction of allyloxy containing structure unit), were prepared via low temperature solution copolycondensation of p-phenylenediamine, terephthaloyl chloride, and 2,5-bis(allyloxy)terephthaloyl chloride. They were converted to the target copolymers, poly(p-phenylene terephthalamide)-ran-poly[p-phenylene 2,5-diallyl23,6-dihydroxyterephthalamide] (CRPPTA-x), through Claisen rearrangement reaction, as characterized by a comprehensive analyses of NMR, FT-IR, gel permeation chromatography, and differential scanning calorimetry. Although APPTA-x had a poor solubility in common organic solvents, the rearranged products with high co-unit contents, that is, CRPPTA-60, 75, 90, and 100, were readily dissolved in m-cresol, DMF, DMAc, DMSO, and NMP. The effect of these four polymers, used as sizing agents, on the interfacial adhesion between Kevlar fiber and epoxy resin was investigated by the contact angle method, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and microbond tests. Compared with the naked fibers, the sized fibers displayed enhanced surface energy and roughness. The fibers sized with 0.5 wt % CRPPTA-60 solution in NMP exhibited a maximum increase of 19% in interfacial shear strength.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 92%

Synthesis and properties of poly(p-phenylene terephthalamide) bearing both polar and unsaturated substituents introduced via claisen rearrangement reaction

Wang

Guan

et al. 2016

J. Polym. Sci. Part A: Polym. Chem.

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“…After 18 h, the values of [η] of the polymers increased and that for the polymer prepared at C ad of 2.5% reached 0.51 dL·g −1 while maintaining the plate-like morphology as shown in Figure c. The number-average molecular weight ( M n ) and its distribution ( M w / M n ) were evaluated by SEC after N -methylation according to a previously reported procedure . The values of [η], M n , and M w / M n were plotted as a function of total concentration in Figure , and SEC profiles were shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Direct Synthesis of Wholly Aromatic Polyamides by Using Reaction-Induced Crystallization

et al. 2009

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Direct synthesis of rigid-rod aromatic polyamides was studied without condensation reagents by using reaction-induced crystallization of oligomers during solution polymerization. Polymerizations of p-aminobenzoic acid were carried out in an aromatic solvent at a polymerization concentration of 20% at 350 °C. High molecular weight poly(p-benzamide) (PBA) was obtained in the form of plate-like crystals, and the highest molecular weight was 11.6 × 103. In this polymerization, the oligomers were formed in the solution by the condensation reaction with the elimination of water. When the molecular weight of oligomers exceeded the critical value, the oligomers were precipitated by crystallization via supersaturated state to form the plate-like crystals. The molecular weight increased by the polymerization between the oligomers on and in the crystals. Poly(p-phenylene isophthalamide) (PPIA) was also obtained in the form of plate-like crystals by the polymerization of p-phenylene diamine (PPDA) and isophthalic acid (IPA) under the same condition as that of PBA. These results exhibited the thermally direct synthesis of infusible aromatic polyamides. Sequential addition of monomers into this heterogeneous polymerization was examined to increase the molecular weight. In the step-growth polymerization, the addition of monomers into the homogeneous polymerization could not increase the molecular weight because it was determined by the extent of reaction and reshuffled by the transamidation reaction. However, the addition of PPDA and IPA during the polymerization resulted in the increase in the molecular weight of PPIA. This result gave possibly a novel procedure for the preparation of high molecular weight condensation-type polymers.

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“…This is due to the insolubility of these polymers originating from the “hard” urea‐segments in the polymer chain, which form hydrogen bonds . By N ‐methylation, the hydrogen bonds of the urea‐segments can be broken, and thus, the N ‐methylated polymers were well‐soluble in DMF for GPC measurements. These polymers are observed with molecular weights up to 8.7 kg mol −1 and a PDI as low as 1.36.…”

Section: Resultsmentioning

confidence: 99%

Metallocene supported on porous and nonporous polyurethane particles for ethylene polymerization

Dorresteijn

Nietzel

Joe

et al. 2013

J. Polym. Sci. Part A: Polym. Chem.

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INTRODUCTIONThe combination of metallocenes with trialkylaluminoxane has opened a new era of producing polyolefins with tailor-made properties.1,2 The novelty of metallocene catalysis, in contrast to Ziegler-Natta systems, is the single-site character of the active species which generates polymers with narrow, monomodal Flory-size distributions. By tailoring the ligands of the metallocenes, polyolefins with specific properties can be produced through the control of tacticity and the incorporation of discrete ratios of comonomers.3,4 Despite these outstanding properties, however, their use in industrial applications under homogeneous conditions at polymerization temperature below the melt point encounters some problems such as low bulk density of the product, a very large amount of methylaluminoxane (MAO) as co-catalyst, lack of morphology control, and reactor-fouling. The polymers produced from homogeneous olefin polymerization via metallocenes are obtained only in dust or lump form which is not suitable for industrial applications. For better processability, a flowable powder is required which can only be produced by supporting metallocenes on solid carriers.

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N‐methylation of wholly aromatic polyamides for size‐exclusion chromatography

Cited by 7 publications

References 13 publications

Synthesis and properties of poly(p-phenylene terephthalamide) bearing both polar and unsaturated substituents introduced via claisen rearrangement reaction

Synthesis and properties of poly(p-phenylene terephthalamide) bearing both polar and unsaturated substituents introduced via claisen rearrangement reaction

Direct Synthesis of Wholly Aromatic Polyamides by Using Reaction-Induced Crystallization

Metallocene supported on porous and nonporous polyurethane particles for ethylene polymerization

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