Compatibility in immiscible poly(ether ether ketone)/poly(ether sulfone) blends

Both as-molded and annealed poly(ether ether ketone) (PEEK)/poly(ether sulfone) (PES) blends have been prepared by direct injection molding. The system has been found to be immiscible at all compositions; however, as a result mainly of the produced morphology, it surprisingly maintains to a very great extent the excellent mechanical performance of both of the pure components. This mechanical response is compared with that of the compression molded blends. The ductility of these blends when quenched appears close to the linear between that of the two components. Leaving aside possible morphological and excess free volume of mixing effects, it is in part attributed to the nature of the blend itself. © 1995 John Wiley & Sons, Inc.     

Fine poly(ether ether ketone) powders

The physical form of polymers is often important for carrying out subsequent processing operations. For example, fine powders are desirable for molding and sintering compounds because they consolidate to produce void free components. The objective of this work is to prepare fine polymeric particulates suitable for processing into fiber reinforced polymer matrix composites. Micron size particles of poly(ether ether ketone) (PEEK) were prepared by rapidly quenching solutions of these materials. PEEK pellets were dissolved at temperatures near the PEEK melting point in a mixture of terphenyls and quaterphenyls; then the solution was quenched to a temperature between the T_g and T_m (≈ 225°C) by adding a room temperature eutectic mixture of diphenyl ether and biphenyl. A supersaturated, metastable solution of PEEK resulted, causing rapid nucleation. Fine PEEK particles rapidly crystallized from this solution. The average particle size was measured using transmission electron microscopy, atomic force microscopy, and by light scattering of aqueous suspensions which had been fractionated by centrifugation. The average particle diameter was about 0.6 μm. Three dimensional photomicrographs obtained via atomic force microscopy showed some aggregates in the suspensions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1571–1578, 1997     

Phase and crystallization behavior of solution-blended poly(ether ether ketone) and poly(ether imide)

Results on solution-blended poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) blends are reported. Dichloroacetic acid was used as the cosolvent for blending. PEEK and PEI are confirmed to be miscible in the melt. The glass transition, T_g, behavior obeys the simple Fox equation or the Gordon-Taylor equation with the adjustable coefficient k = 0.86. This agrees with prior data on melt-blended PEEK/PEI blends. The T_g width of the amorphous PEEK/PEI blends was found to be broader than that of the pure components. The maximum broadening is about 10°C. The specific volume of the amorphous PEEK/PEI blends shows a slight negative deviation from linearity, indicating favorable interaction between PEEK and PEI. The spherulitic growth and resultant blend morphology at 270°C were studied by a cross-polarized optical microscope. The radial growth rate of PEEK spherulites formed from the miscible melt at 270°C decreases from 3.04 μm/min for PEEK/PEI 90/10 blend to 0.77 μm/min for PEEK/PEI 70/30 blend. The decrease in crystalization rate of PEEK from PEEK/PEI blends is attributable to the increase in blend T_g. A linear growth was observed for PEEK spherulites formed from miscible melt at 270°C in the early growth stage. The spherulitic growth deviated from linearity in the late stage of growth. PEEK spherulites formed from the miscible PEEK/PEI melt at 270°C are essentially volume-filling. The branches of the spherulites become more clear for PEEK spherulites formed from the blend than that formed from pure PEEK melt.     

Upper critical solution temperature behaviour in poly(ether ether sulphone)/poly(ether ether ketone-co- ether ether sulphone) blends

Upper critical solution temperature (u.c.s.t.) phase behaviour was found in blends of the homopolymer poly(oxy-1,4-phenyleneoxy-1,4-phenylenesulphonyl-1,4-phenylene) (PEES) with the copolymer poly(oxy-l,4-phenyleneoxy-l,4-phenylenecarbonyl-l,4-phenylene-co-oxy-l,4-phenyleneoxy-1,4-phenylenesul-phonyl-1,4-phenylene) (COPEEKS) for copolymer compositions ranging from 43 mol% to 56 mol% of ether ether ketone (EEK) repeat units. Blend compositions studied ranged from 25wt% to 75wt% of PEES. The consolute temperature was found to occur at a PEES/COPEEKS blend composition of about 50/50 wt% and to increase with the EEK repeat unit content of the copolymer. This miscibility behaviour was interpreted, using a mean-field theoretical approach, in terms of a single positive segmental interaction parameter which ranged from 0.054 to 0.032.     

Thermal properties of melt‐blended poly(ether ether ketone) and poly(ether imide)

The thermal properties of blends of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) prepared by screw extrusion were investigated by differential scanning calorimetry. From the thermal analysis of amorphous PEEK–PEI blends which were obtained by quenching in liquid nitrogen, a single glass transition temperature (T_g) and negative excess heat capacities of mixing were observed with the blend composition. These results indicate that there is a favorable interaction between the PEEK and PEI in the blends and that there is miscibility between the two components. From the Lu and Weiss equation and a modified equation from this work, the polymer–polymer interaction parameter (χ₁₂) of the amorphous PEEK–PEI blends was calculated and found to range from −0.058 to −0.196 for the extruded blends with the compositions. The χ₁₂ values calculated from this work appear to be lower than the χ₁₂ values calculated from the Lu and Weiss equation. The χ₁₂ values calculated from the T_g method both ways decreased with increase of the PEI weight fraction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 733–739, 1999     

Spherulitic growth kinetics in miscible blends of poly(ether ether ketone) and poly(ether imide)

Growths of poly(ether ether ketone) (PEEK) spherulites from both pure melt and its miscible blends with poly(ether imide) (PEI) have been studied by polarized optical microscopy. The nucleation density of PEEK spherulites was depressed upon blending with PEI, which can be attributed to the reduction in degree of supercooling arising from equilibrium melting point depression. A modified Lauritzen-Hoffman (L-H) theory was adopted to analyze the growth kinetics. Regime III-II transition was observed with the transition temperature decreasing with increasing PEI composition. Assuming free rotations of the virtual bonds in PEEK molecule, the side surface free energy of 12.0 erg/cm² was calculated from the characteristic ratio. The fold surface free energy of 188 erg/cm² and work of chain folding of 12.3 kcal/mol were then obtained from the modified L-H analysis.     

Effect of dihydroxydiphenyl ether on poly(ether ether ketone)

A series of modified poly(ether ether ketone) (PEEK) polymers were synthesized by introduction of addition ether groups from dihydroxydiphenyl ether (DHDE) into the PEEK structure. The inherent viscosity of the DHDE-modified PEEK increased with reaction time at 320 °C. DSC thermograms showed the melting points of the obtained PEEK decreased with the increase of the DHDE content in the backbone. The degradation temperature (T_d) was slightly decreased by the introduction of DHDE. The crystallinity as measured via the X-ray diffraction (XRD) increases with the introduction of DHDE into the modified PEEK. The crystalline structure was identified as an orthorhombic structure with lattice constants a = 7.72 Å, b = 5.86 Å, and c = 10.24 Å. Due to the glass transition temperature (T_g) and the melting temperature (T_m) decreasing with the increase of the DHDE content in the reaction system. the processability of the resultant PEEK could be improved through this DHDE modification.     

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 and properties of copolymers of poly(ether ketone ketone) and poly(ether amide ether amide ether ketone ketone)

Poly(aryl ether ketone)s (PAEKs) are a class of high‐performance engineering thermoplastics known for their excellent combination of chemical, physical and mechanical properties, and the synthesis of semicrystalline PAEKs with increased glass transition temperatures (T_g) is of much interest. In the work reported, a series of novel copolymers of poly(ether ketone ketone) (PEKK) and poly(ether amide ether amide ether ketone ketone) were synthesized by electrophilic solution polycondensation of terephthaloyl chloride with a mixture of diphenyl ether and N,N′‐bis(4‐phenoxybenzoyl)‐4,4′‐diaminodiphenyl ether (BPBDAE) under mild conditions. The copolymers obtained were characterized using various physicochemical techniques. The copolymers with 10–35 mol% BPBDAE are semicrystalline and have markedly increased T_g over commercially available poly(ether ether ketone) and PEKK due to the incorporation of amide linkages in the main chain. The copolymers with 30–35 mol% BPBDAE not only have high T_g of 178–186 °C, but also moderate melting temperatures of 335–339 °C, having good potential for melt processing. The copolymers with 30–35 mol% BPBDAE have tensile strengths of 102.4–103.8 MPa, Young's moduli of 2.33–2.45 GPa and elongations at break of 11.7–13.2%, and exhibit high thermal stability and good resistance to organic solvents. Copyright © 2010 Society of Chemical Industry     

Study of blends of linear poly(ether ether ketone) of high melt viscosity and hyperbranched poly(ether ether ketone)

Linear poly(ether ether ketone) (LPEEK) with high melt viscosity was blended with hyperbranched poly(ether ether ketone) (HPEEK) to enhance its melt processability without sacrificing its comprehensive performance. The advantage of using HPEEK is due to its unique spherical shape, low melt viscosity and ready availability. Rheological measurements show that blending LPEEK with as little as 1 wt% HPEEK results in about 17% reduction of melt viscosity. LPEEK/HPEEK blends only show one glass transition temperature, indicating complete miscibility, which results from the similar molecular structure of the two components. The HPEEK component, as rheology modifier, accelerates the crystallization rate of LPEEK. Notably, with the addition of 3 wt% HPEEK, the mechanical properties of LPEEK are improved. Good miscibility is proposed to be responsible for the improved mechanical properties. Moreover, the addition of HPEEK does not decrease the thermal stability of LPEEK. Copyright © 2011 Society of Chemical Industry.     

聚醚砜/磺化聚醚醚酮共混膜的制备和性能

采用流延法制备了聚醚砜(PES)含量不同的PES/磺化聚醚醚酮(SPEEK)共混膜。PES与SPEEK具有良好的相容性。所制备PES/SPEEK共混膜的含水率、溶胀度和甲醇透过系数均随PES含量的增加而降低。虽然共混膜的质子传导性能有所降低.但阻醇性能和溶胀性能提高,这说明PES/SPEEK共混膜是一种很好的直接甲醇燃料电池用固体高分子电解质膜材料。     

Tensile behaviour and fracture toughness of poly(ether ether ketone)/poly(ether imide) blends

Summary The bulk tensile behaviour of poly(ether ether ketone) and poly(ether imide) homopolymers and their blends has been investigated, and the temperature and strain rate dependence of the yield stress discussed in terms of simple Eyring rate theory. In fracture mechanics tests, the K_IC of PEEK was found to decrease significantly with increasing test speed, whereas the K_IC of PEI showed little rate sensitivity. Therefore, although a gradual increase in K_IC with increasing PEEK content was observed in the blends at low loading rates, this effect was anticipated to be less pronounced at higher loading rates.     

Miscibility and crystallization behavior of poly(ether ether ketone ketone)/poly(ether imide) blends

The miscibility and crystallization behavior of poly(ether ether ketone ketone) (PEEKK)/poly(ether imide) (PEI) blends prepared by melt‐mixing were investigated by differential scanning calorimetry. The blends showed a single glass transition temperature, which increased with increasing PEI content, indicating that PEEKK and PEI are completely miscible in the amorphous phase over the studied composition range (weight ratio: 90/10–60/40). The cold crystallization of PEEKK blended with PEI was retarded by the presence of PEI, as is apparent from the increase of the cold crystallization temperature and decrease of the normalized crystallinity for the samples anealed at 300°C with increasing PEI content. Although the depression of the apparent melting temperature of PEEKK blended with PEI was observed, there was no evidence of depression in the equilibrium melting temperature. The analysis of the isothermal crystallization at 313–321°C from the melt of PEEKK/PEI (100/0, 90/10, and 80/20) blends suggested that the retardation of crystallization of PEEKK is caused by the increase of the crystal surface free energy in addition to the decrease of the mobility by blending PEI with a high glass transition temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 769–775, 2001     

Synthesis and characterization of poly(ether amide ether ketone)/poly(ether ketone ketone) copolymers

A new monomer, N,N′‐bis(4‐phenoxybenzoyl)‐m‐phenylenediamine (BPPD), was prepared by condensation of m‐phenylenediamine with 4‐phenoxybenzoyl chloride in N,N‐dimethylacetamide (DMAc). A series of novel poly(ether amide ether ketone) (PEAEK)/poly(ether ketone ketone) (PEKK) copolymers were synthesized by the electrophilic Friedel‐Crafts solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of diphenyl ether (DPE) and BPPD, over a wide range of DPE/BPPD molar ratios, in the presence of anhydrous AlCl₃ and N‐methylpyrrolidone (NMP) in 1,2‐dichloroethane (DCE). The influence of reaction conditions on the preparation of copolymers was examined. The copolymers obtained were characterized by different physicochemical techniques. The copolymers with 10–25 mol % BPPD were semicrystalline and had remarkably increased T_gs over commercially available PEEK and PEKK due to the incorporation of amide linkages in the main chains. The copolymers III and IV with 20–25 mol % BPPD had not only high T_gs of 184–188°C, but also moderate T_ms of 323–344°C, having good potential for the melt processing. The copolymers III and IV had tensile strengths of 103.7–105.3 MPa, Young's moduli of 3.04–3.11 GPa, and elongations at break of 8–9% and exhibited outstanding thermal stability and good resistance to organic solvents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization and melting behavior of poly(ether ether ketone)/poly(aryl ether sulfone) blends

The crystallization and melting behavior of poly(ether ether ketone) (PEEK) in blends with poly(aryl ether sulfone) (PES) prepared by melt mixing are investigated by differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS). The presence of PES is found to have a notable influence on the crystallization behavior of PEEK, especially when present in low concentrations in the PEEK/PES blends. The PEEK crystallization kinetics is retarded in the presence of PES from the melt and in the rubbery state. An analysis of the melt crystallization exotherm shows a slower rate of nucleation and a wider crystallite size distribution of PEEK in the presence of PES, except at low concentrations of PES, where, because of higher miscibility and the tendency of PES to form ordered structures under suitable conditions, a significantly opposite result is observed. The cold crystallization temperature of the blends at low PES concentration is higher then that of pure PEEK, whereas at a higher PES concentration little change is observed. In addition, the decrease in heat of cold crystallization and melting, which is more prevalent in PEEK‐rich compositions than in pure PEEK, shows the reduction in the degree of crystallinity because of the dilution effect of PES. Isothermal cold crystallization studies show that the cold crystallization from the amorphous glass occurs in two stages, corresponding to the mobilization of the PEEK‐rich and PES‐rich phases. The slower rate of crystallization of the PEEK‐rich phase, even in compositions where a pure PEEK phase is observed, indicates that the presence of the immobile PES‐rich phase has a constraining influence on the crystallization of the PEEK‐rich phase, possibly because of the distribution of individual PEEK chains across the two phases. The various crystallization parameters obtained from WAXS analysis show that the basic crystal structure of PEEK remains unaffected in the blend. Further, the slight melting point depression of PEEK at low concentrations of PES, apart from several other morphological reasons, may be due to some specific interactions between the component homopolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2906–2918, 2003     

Synthesis and characterization of poly(ether sulfone) and poly(ether sulfone ketone) copolymers

Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by physicochemical and spectroscopic techniques. All polymers were found to be amorphous, and the glass transition temperature (T_g) was found to increase with the sulfonyl content of the polymers. ¹³C-nuclear magnetic resonance (NMR) spectral data was interpreted in terms of the compositional triads, BAB, BAC, CAC, ABA, and ABB, and indicate that transetherification occurs at high concentration of DFBP units in the polymer (IV). The good agreement between the observed and calculated feed ratios validates the triad analysis. Thermal decomposition studies reveal that the thermal stability of the polymers increases with increase in the carbonyl content in the polymer. Activation energies for thermal decomposition were found to be in the range of 160–203 kJ mol⁻¹ with the cleavage of ϕ SO₂ bond being the preponderant mode of decomposition and depended on the block length of the sulfonyl unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2113–2121, 1999     

Rheological properties in blends of poly(aryl ether ether ketone) and liquid crystalline poly(aryl ether ketone)

Rheological properties of the blends of poly(aryl ether ether ketone) (PEEK) with liquid crystalline poly(aryl ether ketone) containing substituted 3‐trifluoromethylbenzene side group (F‐PAEK), prepared by solution precipitation, have been investigated by rheometer. Dynamic rheological behaviors of the blends under the oscillatory shear mode are strongly dependent on blend composition. For PEEK‐rich blends, the systems show flow curves similar to those of the pure PEEK, i.e., dynamic storage modulus G′ is larger than dynamic loss modulus G″, showing the feature of elastic fluid. For F‐PAEK‐rich systems, the rheological behavior of the blends has a resemblance to pure F‐PAEK, i.e., G″ is greater than G′, showing the characteristic of viscous fluid. When the PEEK content is in the range of 50–70%, the blends exhibit an unusual rheological behavior, which is the result of phase inversion between the two components. Moreover, as a whole, the complex viscosity values of the blends are between those of two pure polymers and decrease with increasing F‐PAEK content. However, at 50% weight fraction of PEEK, the viscosity‐composition curves exhibit a local maximum, which may be mainly attributed to the phase separation of two components at such a composition. The changes of G′ and G″ with composition show a trend similar to that of complex viscosity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4040–4044, 2006     

Synthesis and properties of poly(ether ether ketone ketone)–poly(ether sulfone) block copolymers

Poly(ether ether ketone ketone)-poly(ether sulfone) (PEEKK/PES) block copolymers were prepared from the corresponding oligomers via a nucleophilic aromatic substitution reaction, and the M _n of the PEEKK segment was fixed at 12,000, while the M _n's of the PES segment ranged from 250 to 12,680. The different properties of the copolymers were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The results showed that the relationship between T_g and compositions of copolymers approximately followed the formula 1/T_g = W₂/T_g2. The PES content and the segment length of the copolymers had a significant influence on their melting points and crystallization behavior. The thermal properties and dynamic mechanical behavior of the copolymers were also studied. In the study of isothermal crystallization, the copolymers have the same nucleation mechanism and crystal growth as that of pure PEEKK. Owing to the introduction of the PES segment into the PEEKK main chain, it increases the free energy which forms the critical crystal nucleus and produces a resistant action to the whole crystallization process of the PEEKK segment. © 1996 John Wiley & Sons, Inc.     

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.     

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.