Nonisothermal melt and cold crystallization kinetics of poly(aryl ether ether ketone ketone)

Analysis of the nonisothermal melt and cold crystallization kinetics of poly(aryl ether ether ketone ketone) (PEEKK) was performed by using differential scanning calorimetry (DSC). The Avrami equation modified by Jeziorny could describe only the primary stage of nonisothermal crystallization of PEEKK. And, the Ozawa analysis, when applied to this polymer system, failed to describe its nonisothermal crystallization behavior. A new and convenient approach for the nonisothermal crystallization was proposed by combining the Avrami equation with the Ozawa equation. By evaluating the kinetic parameters in this approach, the crystallization behavior of PEEKK was analyzed. According to the Kissinger method, the activation energies were determined to be 189 and 328 kJ/mol for nonisothermal melt and cold crystallization, respectively.

Crystallization process and morphology structure of poly(aryl ether ether ketone ketone) containing meta-phenyl links

The crystallization process and morphology of poly(aryl ether ether ketone ketone) containing meta-phenyl links (PEEKmK) have been investigated by transmission electron microscopy and electron diffraction. The results indicate that the thin films of PEEKmK isothermally crystallized from both the glassy state and the melt at the temperature range of 180 similar to 250 degrees C consist of two kinds of morphological forms, i. e. large (order of mu m), flat-on single crystals and narrow, lath-like, edge-on lamellae, The latter consists of the spherulites. Meanwhile, the growing process of the two kinds of morphological forms has been discussed.

The crystal structure and drawing induced polymorphism in poly(aryl ether ketone)s .3. Crystallization during hot-drawing of poly(ether ether ketone ketone)

The evolution of crystallinity and polymorphism during hot-drawing of amorphous poly(ether ether ketone ketone) (PEEKK) as a function of strain rate, draw ratio, and temperature was investigated. In modification I, the competition of chain extension and molecular alignment is responsible for the strain rate and temperature dependence. Modification II crystallization is basically controlled by chain extension during stretching. The former can be transformed into the latter via relaxation during stretching or annealing at elevated temperature.

Crystal structure and crystallinity of poly(aryl ether biphenyl ether ketone ketone)

The crystal structure of poly(aryl ether biphenyl ether ketone ketone) (PEDEKK) was determined to comprise a two-chain orthorhombic unit cell with dimensions a 0.778 nm, b = 0.606 nm and c = 2.375 nm by using wide-angle X-ray diffraction (WAXD). According to the orthorhombic system, the 12 reflections of this polymer were indexed. The crystallite size increases with increasing the crystallization temperature. The results of the degree of crystallinity (W-c,W-x) calculated from WAXD were compatible with those from density (W-c,W-d) and calorimetry (W-c,W-h) measurements.

Laser light scattering of the molecular weight distribution of unfractionated phenolphthalein poly(aryl ether sulfone)

Two unfractionated samples of phenolphthalein poly( aryl ether sulfone) (PES-C) were characterized in CHCl3 at 25 degrees C by applying a recently developed laser light-scattering (LLS) procedure. The Laplace inversion of precisely measured intensity-intensity time correlation function lead us first to an estimate of the characteristic line-width distribution G(Gamma) and then to the translational diffusion coefficient distribution G(D). A combination of static and dynamic LLS results enabled us to determine D = (2.69 x 10(-4))M(-0.553), which agrees with the calibration of D = (2.45 x 10(-4))M(-0.55) previously established by a set of narrowly distributed PES-C samples. Using this newly obtained scaling between D and M, we were able to convert G(D) into a differential weight distribution f(w)(M) for the two PES-C samples. The weight-average molecular weights calculated from f(w)(M) are comparable to that obtained directly from static LLS. Our results showed that using two broadly distributed samples instead of a set of narrowly distributed samples have provided not only similar final results, but also a more practical method for the PES-C characterization. (C) 1997 John Wiley & Sons, Inc.

Synthesis and properties of poly(aryl ether ether ketone ketone) containing meta-phenyl links

A Series of poly(aryl ether ether ketone ketone) containing meta-phenyl link were synthesized, the general properties were studied by DSC, stretch, impact, etc.. The results indicated that with the raising of meta linkage monomer fractions, the glass transition point decreased, the melting temperature decreased at first, and then disappeared, but for all-meta-linked polymer, T-m appeared once more. And this kind of polymer had good stretch and impact resistance performance.

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .1. Poly(oxybiphenyl-4-4'-diyloxy-1,4-phenylenecarbonyl-1,3-phenylenecarbonyl-1,4-phenylene)

Crystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3-bis(4-fluorobenzoyl)benzene and biphenyl-4,4'-diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The melting and recrystallization process in the temperature range of 250-260 degrees C, far below the next melting temperature (306 degrees C), was identified and found to be responsible for the remarkable changes in lamellar morphology. Based on WAXD and ED patterns, it was found that crystal structure of isotropic-crystalline PEDEKmK obtained under different crystallization conditions (melt-crystallization, cold-crystallization, solvent-induced crystallization, melting-recrystallization, and crystallization from solution) keeps the same mode of packing, i.e., a two-chain orthorhombic unit cell with the dimensions a = 0.784 nm, b = 0.600 nm, and c = 4.745 nm (form I). A second crystal modification (form II) can be induced by uniaxial drawing above the glass transition temperature, and always coexists with form I. This form also possesses an orthorhombic unit cell but with different dimensions, i.e., a = 0.470 nm, b = 1.054 nm, c = 5.064 nm. The 0.32 nm longer c-axis of form II as compared with form I is attributed to an overextended chain conformation due to the expansion of ether and ketone bridge bond angles during uniaxial drawing. The temperature dependence of WAXD patterns for the drawn PEDEKmK suggests that form II can be transformed into the more stable form I by relaxation of overextended chains and relief of internal stress at elevated temperature in absence of external tension.

Crystal structure and its transition for poly(aryl ether ketone ketone)s .1.

Poly(aryl ether ketone ketone)s (PEKK) was a high-performance engineering plastics, By means of Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC) methods, PEKK samples crystallized in solvent induction, from glass state and from melting state were studied, Crystal forms I and II for PEKK were found, The formation of crystal form II was dependent on thermal history and solvent induction, and this form II had melting point 10 degrees C or so lower than that of form I crystallized from glass state, All PEKK samples had low melting peaks which were relevant to the polarization of PEKK molecular chain, while they had nothing to do with thermal history, The heat of fusion for PEKK low melting peaks accounted for,percentage of 2 to 10 or so of the whole heat of fusion, And PEKK has its equilibrium melting point of 409 degrees C.

Synthesis and properties of poly(aryl ether ketone)s containing meta-phenyl links

A series of poly(aryl ether ketone)s containing meta-phenyl links are synthesized, DSC and wide-angle X-ray scattering, etc, are used to study the general properties of the polymers, With the increasing of meta linkage monomer percentage, the melting temperature decreases sharply at first, then rises steadily, the glass transition point. keeps a stable value, and crystallin;ty and crystallizing rate are reduced, A part of amorphous film of the polymer is annealed at different temperatures, DSC scan shows that besides T-m, a new melting peak (T-m') at low temperature appears, And with heat treating temperature rising, T-m' shifts to high temperature, and T-m keeps a stable value.

Effect of heat treatment on the parameters of crystal structure and degree of crystallinity of poly(aryl-ether-ether-ketone)

The variations of unit cell parameters and crystallite size of nine PEEK samples treated at various temperatures have been studied by using Wide-Angle X-ray Diffraction (WAXD), The results indicate a decrease in unit cell parameter a,b and c but an increase in crystallite size L(hkl) With the increase beat treatment temperature. Based on X-ray scattering intensity theory and using the graphic multipeak resolution method, the formula of degree of crystallinity (W-c,W-X) for PEEK is derived. The results calculated are compatible with the density measurement and calorimetry.

Morphological studies on a novel poly(aryl ether ketone)

The morphology of a novel poly(aryl ether ketone) [PEDEKmK] was investigated via polarizing optical microscopy (POM), TEM, DSC, SAXS and electron diffraction (ED). A distinct change in lamellar thickness, orientation, and spherulitic morphology was observed due to crystal melting and recrystallization. However, the crystal packing mode is found to be identical before and after the recrystallization process.

Dynamic light-scattering characterization of the molecular weight distribution of a broadly distributed phenolphthalein poly(aryl ether ketone)

Using a recently developed laser light-scattering (LLS) procedure, we accomplished the characterization of a broadly distributed unfractionated phenolphthalein poly(aryl ether ketone) (PEK-C) in CHCl3 at 25 degrees C. The laplace inversion of precisely measured intensity-intensity time correlation function from dynamic LLS leads us first to an estimate of the characteristic line-width distribution G(Gamma) and then to the translational diffusion coefficient distribution G(D). By using a previously established calibration of D (cm(2)/s) = 2.37 X 10(-4)M(-0.57), were able to convert G(D) into a differential weight distribution f(w)(M). The weight-average molecular weight M(w) calculated from f(w)(M) agrees well with that directly measured in static LLS. Our results indicate that both the calibration and LLS procedure used in this study are ready to be applied as a routine method for the characterization of the molecular weight distribution of PEK-C. (C) 1996 John Wiley & Sons, Inc.

Synthesis and structures of the complexes of beta-alkoxycarbonylethyltin trichlorides with N-aryl-2-hydroxyacetophenylideneimines

Sixteen novel beta-alkoxycarbonylethyltin trichlorides and the corresponding N-aryl-2-hydroxyacetophenylideneimines complexes have been synthesized and characterized. An X-ray crystal structure analysis of the complex of beta-methyloxycarbonylethyltin trichloride and N-4-methylphenyl-2-hydroxyacetophenylideneimine has been performed, The crystal belongs to space group , The cell parameters are: a = 1.0201(6) nm, b = 1.082 2(4) nm, c = 1.394 9(6) nm, alpha = 99.88(3)degrees, beta = 98.63(4)degrees, gamma = 97.86(4)degrees, Z = 2, The ligands coordinate to tin atom via phenolic oxygen atom. Coordination of carbonyl oxygen atom to tin atom still exists in the complexes, The coordination number of tin atom is 6.

Laser light-scattering study of novel thermoplastics .1. Phenolphthalein poly(aryl ether ketone)

Five different molecular weight phenolphthalein poly(aryl ether ketone) (PEK-C) fractions in CHCl3 were studied by static and dynamic laser light scattering(LLS). The dynamic LLS revealed that the PEK-C samples contain some large polymer clusters. These large clusters can be removed by filtering the solution with a 0.1-mu m filter. We found that the persistence length of PEK-C in CHCl3 at 25 degrees C is similar to 2 nm and the Flory characteristic ratio, C-infinity is similar to 25. Our results showed that [R(g)(2)](1/2)(z) = (3.50+/-0.20) x 10(-2)M(w)(0.54+/-0.01) and [D] = (2.37+/-0.05) x 10(-4)M(w)(-0.55+/-0.01), with [R(g)(2)](1/2)(z), M(w), and [D] being the z-average radius of gyration, the weight-average molecular weight, and the z-average translational diffusion coefficient, respectively. A combination of static and dynamic LLS results enabled us to determine D = (2.20+/-0.10) x 10(-4)M(-0.555+/-0.015), where D and M correspond to monodisperse species. Using this calibration between D and M,we have determined molecular weight distributions of five PEK-C fractions from their corresponding translational diffusion coefficient distribution.

STUDIES ON OLEFIN-COORDINATING TRANSITION-METAL CARBENE COMPLEXES .20. SYNTHESIS OF 1,3-CYCLOHEXADIENE(DICARBONYL) [ETHOXY(ARYL)-CARBENE]IRON COMPLEXES AND THEIR PHOSPHINE ADDUCTS - CRYSTAL-STRUCTURE OF C6H8(CO)2FEC(OC2H5)C6H4CH3-O

Reaction of 1,3-cyclohexadiene(tricarbonyl)iron (1) with ortho-substituted aryllithium reagents ArLi (Ar=o-CH3C6H4, o-CH3OC6H4, o-CF3C6H4) in ether at low temperature, and subsequent alkylation of the acylmetalates formed with Et3OBF4 in aqueous solution at 0-degrees-C or in CH2Cl2 at -60-degrees-C gave the 1,3-cyclohexadiene(dicarbonyl)[ethoxy(aryl)carbene]iron complexes (eta4-C6H8)(CO)2FeC(OC2H5)Ar (3, Ar = o-CH3C6H4; 4, Ar = o-CH3OC6H4), and the isomerized product (eta3-C6H8)(CO)2FeC(OC2H5)C6H4CF3-o (5), respectively, among which the structure of 3 has been established by an X-ray diffraction study. Complex 3 is monoclinic, space group P2(1) with a = 8.118(4), b = 7.367(4), c = 14.002(6) angstrom, beta = 104.09(3)-degrees, V = 812.2(6) angstrom3, Z = 2, D(c) = 1.39 g cm-3, R = 0.056, and R(w) = 0.062 for 976 observed reflections. Complexes 3 and 5 were converted into the chelated allyliron phosphine adducts(eta3-C6H8)(CO)2(PR31)FeC(OC2H5)Ar (6, Ar = o-CH3C6H4, R1 = Ph; 7, Ar = o-CH3C6H4, R1 = OPh; 9, Ar = o-CF3C6H4, R1 = Ph), by reaction with phosphines in petroleum ether at low temperatures.