Viscoelastic properties of phenolphthalein poly(ether ketone)

Stress relaxation and dynamic mechanical behavior of phenolphthalein poly(ether ketone) (PEK-C) have been investigated. Using Ferry's reduction method, the master curve was obtained. From the experimental results, we found that the WLF equation is not appropriate in the lower-temperature range (T < T_g). The relaxation spectrum was calculated according to the first approximation method proposed by Schwarzl and Staverman. In addition to the α-transition region, a second transition zone is revealed at low temperature. This transition is probably due to a restricted motion of its main chain. © 1995 John Wiley & Sons, Inc.     

Ductile tearing instability in phenolphthalein poly(ether ketone)

Phenolphthalein poly(ether ketone) (PEK-C) can fail by tearing instability when the elastic contraction is greater than the plastic extension due to crack growth. Tearing instability (TIS) theory developed by Paris and coworkers describes the effect of specimen geometry on the ductile fracture properties of polymers. The stability of crack growth in three-point bend specimens depends on the specimen's dimensions. In this article, tearing instability theory is applied to describe the ductile tearing instability of PEK-C at different temperatures. The temperature dependence of tearing modulus T_m, dJ/dδa, and the relationship between dJ/dδa and yield stress are discussed. © 1994 John Wiley & Sons, Inc.     

Sulfonated poly(aryl ether ketone)s

Several kinds of commercially available polymers of the type poly(oxy-1,4-phenylenecarbonyl-1,4-phenylene) were sulfonated by reaction with mixtures of sulfuric acid and oleum. The ether/carbonyl group ratio of the polymer chain varied from 0.67 to 2.0. With decreasing amounts of ether links in the polymer backbone the sulfonation is hindered and the reaction conditions have to be stronger. To yield the same degree of sulfonation, the sulfuric trioxide concentration of the reaction mixture has to be increased. The achievable degree of substitution is limited, in general, to one sulfonate group per substitutable unit (oxy-phenylene-oxy- or oxy-phenylene-carbonyl unit). In dependence on the polymer structure, polymers with contents of sulfonate groups between 1.2 and 2.0 meq·g^–1 polymer are well soluble in dimethylformamide or N-methylpyrrolidone and it is possible to produce membranes with permselectivities >96% and electrical resistances < 2 Ω cm^–2. The sulfonated polymers were characterized by viscosimetry, sedimentation analysis and ¹³C NMR spectroscopy.     

Miscibility and phase behavior in blends containing random copolymers of poly(ether ether ketone) and phenolphthalein poly(ether ether ketone)

The miscibility and phase behavior of polysulfone (PSF) and poly(hydroxyether of bisphenol A) (phenoxy) with a series of copoly (ether ether ketone) (COPEEK), a random copolymer of poly(ether ether ketone) (PEEK), and phenolphthalein poly(ether ether ketone) (PEK-C) was studied using differential scanning calorimetry. A COPEEK copolymer containing 6 mol % ether ether ketone (EEK) repeat units is miscible with PSF, whereas copolymers containing 12mol % EEK and more are not. COPEEK copolymers containing 6 and 12 mol % EEK are completely miscible with phenoxy, but those containing 24 mol % EEK is partially miscible with phenoxy. Moreover, a copolymer containing 17 mol % EEK is partially miscible with phenoxy; the blends show two transitions in the midcomposition region and single transitions at either extreme. Two T_gs were observed for the 50/50 blend of phenoxy with the coplymer containing 17 mol % EEK, whereas a single composition-dependent T_g appeared for all the other compositions. An FTIR study revealed that there exist hydrogen-bonding interactions between phenoxy and the copolymers. The strengths of the hydrogen-bonding interactions in the blends of the COPEEK copolymers containing 6 and 12 mol % EEK are the same as that in the phenoxy/PEK-C blend. However, for the blends of copolymers containing 17, 24, and 28 mol % EEK, the hydrogen-bonding interactions become increasingly unfavorable and the self-association of the hydroxyl groups of phenoxy is preferable as the content of EEK units in the copolymer increases. The observed miscibility was interpreted qualitatively in terms of the mean-field approach. © 1996 John Wiley & Sons, Inc.     

Reinforced effect of wollastonite on phenolphthalein poly(ether ketone)

The mechanical properties of wollastonite-filled phenolphthalein poly-(ether ketone) (PEK-C) composites have been studied at room temperature and 200°C. The dispersion of wollastonite particles in PEK-C matrix were investigated by means of scanning electron microscope. The modulus and strength of the composites increased with filler content. The reinforced effect of wollastonite on PEK-C is more marked at elevated temperature. The glass transition temperature of the composites is higher than that of PEK-C and is independent of filler content. The restriction effect of filler particles on the molecular mobility of the polymer matrix should be attributed to the reinforcement. © 1997 John Wiley & Sons, Inc. J Appl Polym 65: 649–653, 1997     

Crosslinkable fully aromatic poly(aryl ether ketone)s bearing macrocycle of aryl ether ketone

A novel bisphenol monomer, (3-methoxy)phenylhydroquinone, was synthesized via a three-step synthetic procedure. The cyclization of the bisphenol monomer and 4,4-difluorobenzophenone was carried out under pseudo high dilution condition. Two types of fully aromatic poly(aryl ether ketone)s were prepared by copolymerization of macrocycle of aryl ether ketone (MACEK) containing hydroxyphenyl, 4,4′-(hexafluoroisopropylidene)diphenol (HFBPA), and 4,4-difluorobenzophenone. The copolymers have high molecular mass, good solubility and high glass transition temperatures. The copolymers are crosslinkable in the presence of basic initiator and the glass transition temperatures of the copolymers increased greatly after the curing. These cured copolymers exhibit excellent thermal stability, and the 5% weight loss temperatures are around 500 °C in nitrogen.     

Blends of phenolphthalein poly(ether ether ketone) and a thermotropic liquid crystalline copolyester

Blends of phenolphthalein poly(ether ether ketone) (PEK-C) and a thermotropic liquid crystalline copolyester (LCP), poly[(1-phenylethyl-p-phenylene terephthalate)-co-(1-cumyl-p-phenylene terephthalate)], was prepared via melt mixing. The studies of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) indicate that the PEK-C/LCP blends display two glass transition temperatures which correspond to those of PEK-C- and LCP-rich phases, respectively. The PEK-C/LCP blends were judged to be partially miscible. Scanning electron microscopy (SEM) was employed to examine the morphology of the blends, and it was observed that all the PEK-C/LCP blends displayed a phase-separated structure. The interface between the PEK-C- and LCP-rich phases is poor. The Young's modulus of the PEK-C/LCP blends was found to increase with LCP content due to the high modulus of the LCP. However, the tensile strength and the elongation at break of the blends greatly decreases with increase of LCP content, owing to the poor interfacial adhesion. From the thermogravity analysis (TGA), it was observed that all the blends exhibited a two-step weight loss mechanism, and the thermal degradation onset temperature of the blends was lowered with the addition of LCP content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1923–1931, 1998     

Nonisothermal crystallization behavior of poly(aryl ether ether ketone)

A study has been made of the crystallization behavior of poly(aryl ether ether ketone), PEEK, under nonisothermal conditions. A differential scanning calorimeter (DSC) was used to monitor the energetics of the crystallization process from the melt. For nonisothermal studies, the melt was crystallized by cooling at rates from 1°C/min to 10°C/min. A kinetic analysis based on the recently proposed model for nonisothermal crystallization kinetics to remedy the drawback of the Ozawa equation was applied. The Avrami exponent for the nonisothermal crystallization process was strikingly different from that of the isothermal process, which indicates different crystallization behaviors. The results agree with the morphological observation reported in the literature. This study shows that correct interpretation of the Avrami exponent provides valuable information about the crystal structure and its morphology.     

Physical aging and crystallization of amorphous poly(aryl ether ether ketone ketone)

Physical aging of poly(aryl ether ether ketone ketone) (PEEKK) was investigated. Heat flow responses were measured after annealing the amorphous samples that were obtained by quenching the melt into an ice-water bath at just below the glass transition temperature. 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 form was used to evaluate the relaxation activation energy of physical aging and the transport activation energy of isothermal crystallization. The activation energy of physical aging was similar in magnitude to that observed for the temperature dependence of crystallization under conditions of transportation control. Results obtained were interpreted as purely kinetic effects associated with the glass formation process. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 907–912, 1998     

Lamellar morphology of high molecular weight poly(ether ether ketone) after rolltrusion

A rolltrusion technique has been applied to impose high molecule orientation in unreinforced poly(ether ether ketone). The relationships among processing, microstructure and properties were characterized. The morphology was controlled and investigated in the microstructural levels of crystallinity, chain orientation, lamellae and spherulite colony. The density measurements detected an increase in crystallinity after rolltrusion. Wide-angle X-ray scattering (WAXS) diffraction experiments showed the preferred c-axis chain orientation along the rolltrusion direction. The internal microstructure, revealed by permanganic etching and scanning electron microscopy (SEM), changed from randomly distributed lamellae to a row structure. The lamella thickness was estimated to be about 100 Å.     

Miscibility of phenolphthalein poly(ether ether ketone) with poly(hydroxy ether of bisphenol A) and polysulfone

Summary A novel poly(ether ether ketone) (PEK-C) from phenolphthalein was found to be miscible with poly(hydroxy ether of bisphenol A) (phenoxy) as shown by the existence of a single glass transition temperature (Tg) in each blend. A FTi.r. study revealed that a hydrogen-bonding interaction occurs between these two polymeric components and its strength is weaker than that in pure phenoxy. FEK-C was judged to be miscible with polysulfone based on the existence of a single composition-dependent glass transition temperature.     

Synthesis of a new electroactive poly(aryl ether ketone)

In this communication, we report for the first time the synthesis of a new electroactive poly(aryl ether ketone) derived from the phenyl-capped aniline tetramer. The general properties are studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymer has high serving temperature and good thermal stability. And its chemical oxidation process was studied by UV-Vis spectra. It was found the polymer was oxidized to its EB form and then to the pernigraniline oxidation state, which is same as the PANI.     

Bulk crystallization of poly(aryl ether ether ketone) (PEEK)

Concurrent measurements of transmitted polarized light intensity and recording of the phenomenon of crystallization through polarized optical microscopy have resolved some of the controversies on the bulk crystallization behavior of poly(aryl ether ether ketone) (PEEK). The process of bulk crystallization was studied through the separation of the nucleation and growth steps. Avrami plots have shown three characteristic ranges. It was observed that a first slope at low crystallization times is associated with massive heterogeneous nucleation and/or local-order-promoted primary nucleation of spherulitic crystals. A second gradual decrement in intensity follows, showing a logarithmic tendency. It represents a mixture of at least three parallel mechanisms. These are associated with the end of the process of crystallization of the primary spherulites and in large proportion the nucleation and growth, at lower rates, of sporadically nucleated spherulites. In addition, there is some contribution from secondary crystallization to the transmitted light emerging. The whole group of nucleated spherulites continue growing up to the point of impingement, which loosely marks the beginning of the third region. This last region with lower slope than the first one and an exponential tendency reflects secondary crystallization at long times. The general characteristics of the processes of nucleation and growth are discussed.     

Water sorption kinetics in poly(aryl ether ether ketone)

The kinetics of diffusion of water from different activity vapors and liquid phase have been investigated in glassy amorphous poly(aryl ether ether ketcne) (PEEK) films at the temperature of 60°C and in glassy semicrystalline PEEK sheets at different temperatures, respectively. In the case of the amorphous PEEK films (250 μm thick) the data at low activity levels were interpreted by means of a purely Fickian mechanism. At higher activity levels the material has shown the presence of a relaxation process; in this case the data have been interpreted using a model proposed by Berens and Hopfenberg. Equilibrium sorption isotherm is also reported. Liquid water sorption in semicrystalline (30%) PEEK sheets (2 mm thick) has been determined to follow the classical Fickian mechanism. The water uptake values obtained for both amorphous and semicrystalline PEEK, confirm the good moisture and liquid water resistance of this kind of high performance thermoplastic polymer.     

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

Nonisothermal melt and cold crystallization kinetics of poly(aryl ether ketone ether ketone ketone) (PEKEKK) were investigated by differential scanning calorimetry (DSC). The Avrami equation modified by Jeziorny could only describe the primary stage of nonisothermal crystallization kinetics of PEKEKK. Also, the Ozawa equation could not describe its nonisothermal crystallization behavior. A convenient and reasonable kinetic approach was used to describe the nonisothermal crystallization behavior. The crystallization activation energy were estimated to be −264 and 370 KJ/mol for nonisothermal melt and cold crystallization by the Kissinger method. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2865–2871, 2000     

含氰侧基联苯型聚芳醚醚酮酮的合成及表征

通过一种反应条件较为温和的反应新工艺,合成联苯二甲酰氯,即4,4’-二氯甲酰基联苯(BC IBP)。然后,在无水A lC l3及N-甲基吡咯烷酮(NMP)/1,2-二氯乙烷(DCE)复合溶剂的存在下,将2,6-二苯氧基苯甲腈(DPOBN)与BC IBP进行低温缩聚反应,合成了一类新型含氰侧基联苯型聚芳醚醚酮酮。用IR,DSC,TG,WAXD及元素分析等方法对其结构和性能进行了表征。结果表明,所合成的聚合物具有预期结构且为非晶态聚合物;其玻璃化转变温度(Tg)为211℃,在氮气气氛中及在空气气氛中的热分解5%的温度(Td)分别为523℃及498℃,说明其具有突出的耐高温性能;聚合物除了能在浓H2SO4,CF3COOH/CHC l3等强质子性溶剂当中溶解外,对其他的溶剂均不溶解,说明聚合物具有优异的耐化学腐蚀性能。     

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.     

Mechanical properties of miscible phenolphthalein poly(ether ether ketone)/polysulfone blends

The properties of miscible phenolphthalein poly(ether ether ketone) (PEK-C)/polysulfone blends have been measured by dynamic mechanical analysis and tensile testing. The blends are found to have single glass transitions that vary continuously with the composition. The tensile moduli exhibit positive deviations from simple additivity as expected for miscible blends. Remarkably, positive deviations were also observed for tensile strength. Embrittlement, or transition from the brittle to ductile mode of failure, occurs at 50-30 wt % PEK-C. These observations suggest that mixing on the segmental level has occurred and that there is enough interaction between the components to retard internal mobility significantly.