Isothermal and nonisothermal crystallization of poly(aryl ether ketone ketone) with all-para phenylene linkage

Isothermal and nonisothermal crystallization behavior for PEKK(T) was studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron diffraction (ED). In the isothermal crystallization process, the Avrami parameters obtained were n = 2.33-2.69, which shows crystal growth of two-dimensional extensions consistent with our observations by TEM. The lamellar thickness increases with the crystallization temperature of PEKK(T) crystallized isothermally from the melt. However, for the nonisothermal crystallization of PEKK(T), the results from the modified Avrami analysis show two different crystallization processes. Avrami exponents n(1) = 3.61-5.30, obtained from the primary crystallization process, are much bigger than are the secondary n(2) = 2.26-3.04 and confirmed by the observation of the spherulite morphology. PEKK(T) crystallized isothermally from the melt possesses the same crystal structure (Form I) as that from nonisothermal melt crystallization. The results from TEM observation show that the spherulite radius decreases with an increasing cooling rate. (C) 2001 John Wiley & Sons, Inc.

Shear-induced spiral-like morphology of a main-chain liquid crystalline poly(aryl ether ketone)

The shear-induced spiral-like morphology of a main-chain thermotropic liquid crystalline poly(aryl ether ketone) is observed and characterized by means of polarizing light microscopy, atomic force microscopy, transmission electron microscopy and electron diffraction techniques. The spiral-like texture is formed during shearing in the temperature range of liquid crystalline to isotropic transition (335-340 degreesC), and dispersed discontinuously in the mosaic matrix. Electron diffraction results indicate that the spiral exhibits orthorhombic lateral packing of the crystals and homeotropic alignment of the molecules. The spiral formation process and possible affecting factors are discussed.

Homoepitaxial crystallization in films of a thermotropic liquid crystalline chloro-poly(aryl ether ketone)

The homoepitaxial crystallization in the films of a thermotropic liquid crystalline chloro-ply(aryl ether ketone) is studied by transmission electron microscopy (TEM) and electron diffraction (ED). The homoepitaxy takes place in the temperature range 330-320 degreesC, in which a highly-ordered smectic crystalline phase of the copolymer with a single-crystal-like banded structure is formed during the cooling process from the isotropic melt. The homoepitaxial crystallizations with angles of 32 degrees and 122 degrees between the two b axes are the major populations observed, and possess epitaxial contact planes of (100)(I)-(210)(II) and (010)(I)-(210)(II); respectively.

Synthesis and characterization of novel sodium sulfonate-functionalized poly(ether ether ketone)s containing cyclohexyl side groups

Novel water insoluble sodium sulfonate-functionalized poly(ether ether ketone)s containing cyclohexylidene in the main chain with degree of sulfonation up to 2.0 were synthesized from nucleophilic polycondensation of 5, 5'-carbonylbis (2-fluorobenzenesulfonate), 4, 4'-difluorobenzophenone and 4, 4'-cyclohexylidenebisphenol. The polymers showed excellent thermal stability and good water resistance as well. The DSC diagrams and WAXD patterns indicated an amorphous morphological structure of these polymers. A comprison of some properties between these copolymers and polymers derived from bisphenol A was given.

Synthesis of poly(ether ether ketone)s with high content of sodium sulfonate groups as gas dehumidification membrane materials

Sodium sulfonate-functionalized polyether ether ketone)s derived from Bisphenol A with a degree of sulfonation up to 2.0 were synthesized by aromatic nucleophilic polycondensation of various amounts of 5,5-carbonylbis(2-fluorobenzenesulfonate) (1), 4,4'-diflurobenzophenone (2) and Bisphenol A (2). Copolymers showed excellent thermal stability and good mechanical properties. The selectivity of water vapor over nitrogen of membranes prepared from copolymers 3a and 3h was determined to be 3.43 x 10(6) and 1.05 x 10(7), respectively.

Synthesis and characterization of a series of high sulfonated poly(ether ether ketone)s

A series of high sulfonated poly(ether ether ketone)s were prepared by copolymerization of sodium 5,5 ' -carbonylbis (2-fluorobenzenesulfonate)(2),4,4 ' -difluorobenzophenone (1) and bisphenol A(3) in the presence of potassium carbonate in dimethylsulfoxide. The copolymers were characterized by IR and DSC, The influence of degree of sulfonation on the properties of copolymers, such as component, thermal stability, solubility and filming ability, was studied.

Studies on the structure and properties of thermotropic liquid crystalline poly(aryl ether ketone)s

Series of thermotropic liquid crystalline poly (aryl ether ketone) s were synthesized by mucleophilic substitution reactions of 4,4'-biphenol and substituted hydroquinone with different difluoromonomers, The relationship between structure and properties of the novel copolymers was investigated. For the copolymers with liquid crystalline properties, their melting transition temperatures show no great change with increase the content of the crystal-disrupting unit. The reason is that the crystal phase is directly transformed from the ordered liquid crystal phase. Side-groups have important effect on mesophase stability, The temperature range of mesophase stability for the chloro-polymers is smaller than those of other series of copolymers (P-phenyl, t-butyl, methoxy, 3-trifluoromethylbenzene). This behavior indicates that the effect of geometric repulsive factor on the thermodynamic stability of the mesophase is much larger than that of the polarizability attractive factor. Different ordered liquid crystal phases are observed in the polymers with different molecular weights. At low molecular weight, highly ordered smectic liquid crystal phases form. With increasing the molecular weight, the ordered degree of the liquid crystals decreases, and only the nematic liquid crystal phase is observed in the polymer with higher molecular weight.

Novel sodium sulfonate-functionalized poly(ether ether ketone)s derived from 4,4 '-thiodiphenol

Novel sodium sulfonate-functionalized poly(ether ether ketone)s derived from 4,4'-thiodiphenol with degree of sulfonation up to 2.0 were synthesized by nucleophilic polycondensation of various amount of 5,5 '-carbonylbis(2-fluorobenzenesulfonate) (1) and 4,4'-difluorobenzophenone (2) with 4,4'-thiodipheno (3). Component and structure of the polymers were confirmed by TR, NMR and elemental analysis. Wide angle X-ray diffraction patterns indicated an amorphous structure of the polymers. All the polymers showed excellent thermal stability and poor solubility in water. (C) 2001 Elsevier Science Ltd. All rights reserved.

Polymerization of methyl methacrylate with organolanthanides as single-component catalysts

It was first found that Ind(2)Y(mu -Et)(2)AlEt2 and Ind(2)LnN(i-Pr)(2) (Ln = Y, Yb) exhibit extremely high catalytic activity in the polymerization of methyl methacrylate. The reactions can be carried out over a quite broad range of polymerization temperatures from -30 to 50 degreesC. PMMA with high molecular weight (7.8 x 10(-5)) and high isotacticity (94%) can be obtained by using Ind(2)Y(mu -Et)(2)AlEt2, and narrow molecular weight distribution (M-w/M-n < 1.5) can be obtained by using Ind(2)LnN(i-Pr)(2) (Ln = Y, Yb).

Effect of physical aging on the microstructure and the crystallization of amorphous poly(aryl ether ether ketone ketone) (PEEKK)

Physical aging of poly(aryl ether ether ketone ketone) (PEEKK) has been investigated. Heat flow responses were measured after annealing the amorphous samples obtained by quenching the melt into an ice-water bath close to, but below, the glass transition temperature. The extent of aging is related to the supercooling from the glass transition temperature and to the aging time. The activation energy of the aging process, which was estimated by a Williams-Watt expression, is similar in magnitude to that obtained for the cold crystallization for the aged samples. The quenched glass is a metastable glass. The conformation of molecular chains rearranges with physical aging which results in the formation of a denser packing in the amorphous phase. The dense amorphous phase may form an initial nucleus for crystallization. Isothermal cold crystallization of the aged samples was carried out. The Avrami equation was used to determine the kinetic parameters, and the Avrami constant n is about 2. An Arrhenius expression was used to evaluate the activation energy of relaxation upon physical aging and the activation energy of transportation upon isothermal crystallization. The activation energy of relaxation is similar in magnitude to that of crystallization for aged samples. Results obtained are interpreted as kinetic effects associated with the glass formation process.

Gas-phase ion - Molecule reactions of neutral C-60 with the plasmas of alkyl methyl ethers and primary alcohols

The gas-phase ion-molecule reactions of C-60 with the methoxymethyl ion [CH3O=CH2](+) and the 1-hydroxyethyl ion [CH3CH=OH](+) generated under the self-chemical-ionization (self-CI) conditions of alkyl methyl ethers and primary alcohols were studied in the ion source of a mass spectrometer. The adduct ions [C60C2H5O](+) and protonated molecules [C60H](+) were observed as the major products of C-60 with the plasma of alkyl methyl ethers. On the contrary, the reactions of C-60 With the plasmas of primary alcohols produced few corresponding adduct ions. The AM1 semiempirical molecular orbital calculations were carried out on 14 possible structures. The calculated results showed that the most stable structure among the possible isomers of [C60C2H5O](+) is the [3+2] cycloadduct. According to experimental and theoretical results, the pathway for the formation of the adduct was presented.

Gas permeability and permselectivity of polyimides prepared from phenylenediamines with methyl substitution at the ortho position

Polyimides were prepared from diamines: 2,4,6-trimethyl-1,3-phenylenediamine (3MPDA) and 2,3,4,5-tetramethyl-1,4-phenylenediamine (4MPDA). 1,4-Bis(3,4-dicarboxyphenoxy)benzene dianhydride (HQDPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3'-4,4'-diphenylsulphone tetracarboxylic dianhydride (SO(2)PDA), 3,3',4,4'-diphenylsulphide tetracarboxylic dianhydride (SPDA), pyromellitic dianhydride (PMDA), and 2,2'-bis(3,4-dicarboxyphenyl)hexa-fluoroisopropane dianhydride (6FDA) were used as dianhydride. The gas permeabilities of H-2, O-2 and N-2 through the polyimides were measured at temperatures from 30 degrees C to 90 degrees C. The results show that as methyl and trifluoromethyl substitution groups densities increase from 7.73 x 10(-3) molcm(-3) to 13.50 x 10(-3)molcm(-3), the peameability of H-2 increases 10-fold at 60% loss of permselectivity of H-2/N-2 however, the permeability of O-2 increases 20-fold at 20% loss of permselectivity of O-2/N-2. For O-2/N-2 separation, PMDA-3MPDA has similar performance to 6FDA-3MPDA and 6FDA-4MPDA; all have higher permeabilities for O-2 than normal polyimides, and the P(O-2)/alpha(O-2/N-2) trade-off relationships lie on the upper bound line for polymers. (C) 1999 Society of Chemical Industry.

Characterization of cyclic arylether ketone (sulfone) containing hexafluoroisopropylidene unit by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

The cyclic aryletherketone( sulfone) oligomers containing hexafluoroisopropylidene unit were characterized by matrix-assisted laser desorption ionization time-of-night mass spectrometry(MALDI-TOF-MS) using Na+ and Ag+ as cationization agents. The affinities of cyclic oligomers to the cation were studied. The analysis result showed that 1,8,9-dithranol, in the presence of silver trifluoroacetate, was very effective for the characterization of cyclic arylether ketone ( sulfone) containing hexafluoroisopropylidene unit.

Synthesis of poly(phenylenesulfidephenylenamine) by self-polycondensation of methyl-(4-anilinophenyl) sulfide with antimony pentachloride

Poly(phenylenesulfidephenylenamine)(PPSA) an alternating copolymer and the hybrid structure of poly(phenylene sulfide)(PPS) and polyaniline(PAn), was synthesized by self-polycondensation of methyl-(4-anilino-phenyl) sulfide with antimony pentachloride and by the acid-induced self-polycondensation of methyl-(4-anilino-phenyl) sulfoxide.