Compatibility studies of sulfonated poly(ether ether ketone)–poly(ether imide)–polycarbonate ternary blends

Binary blends of the sulfonated poly(ether ether ketone) (SPEEK)–poly(ether imide) (PEI) and SPEEK–polycarbonate (PC), and ternary blends of the SPEEK–PEI–PC, were investigated by differential scanning calorimetry. SPEEK was obtained by sulfonation of poly(ether ether ketone) using 95% sulfuric acid. From the thermal analysis of the SPEEK–PEI blends, single glass transition temperature (T_g) was observed at all the blend composition. For the SPEEK–PC blends, double T_gs were observed. From the results of thermal analysis, it is suggested that the SPEEK–PEI blends are miscible and the SPEEK–PC blends are immiscible. Polymer–polymer interaction parameter (χ₁₂) of the SPEEK–PEI blends was calculated from the modified Lu and Weiss equation, and found to range from −0.011 to −0.825 with the blend composition. For the SPEEK–PC blends, the χ₁₂ values were calculated from the modified Flory–Huggins equation, and found to range from 0.191 to 0.272 with the blend composition. For the SPEEK–PEI–PC ternary blends, phase separation regions that showed two T_gs were found to be consistent with the spinodal curves calculated from the χ₁₂ values of the three binary blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2488–2494, 2000     

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     

Synthesis and characterization of poly(ether ketone ketone) (PEKK)/sodium sulfonated poly(arylene ether ketone) (S‐PAEK) block copolymers

A series of well‐defined poly(ether ketone ketone) (PEKK)/sodium sulfonated poly(aryl ether ketone) (S‐PAEK) block copolymers of high molecular weights was prepared by direct nucleophilic polymerization of hydroquinone with sodium 5,5′‐carbonylbis(2‐fluorobenzene sulfonate) ( 1 ) and PEKK oligomer ( 2 ). Varying the ratio of 1 to 2 used in polymerization can be used to control the degree of polymer sulfonation, which correspondingly affects the polymer solubility in solvents. Increasing content of 1 in the copolymers, slightly decreases their thermal stability which is nevertheless thermally stable up to 400 °C. Two T_g values, or one broad T_g, were observed in the DSC measurements of the block copolymers, indicating the existence of phase separation, which was further proved by phase‐separated morphologies as shown in atomic force microscopy images. © 2001 Society of Chemical Industry     

Miscibility and mechanical properties of tetrafunctional epoxy resin/phenolphthalein poly(ether ether ketone) blends

Phenolphthalein poly(ether ether ketone) (PEK‐C) was found to be miscible with uncured tetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM), which is a type of tetrafunctional epoxy resin (ER), as shown by the existence of a single glass transition temperature (T_g) within the whole composition range. The miscibility between PEK‐C and TGDDM is considered to be due mainly to entropy contribution. Furthermore, blends of PEK‐C and TGDDM cured with 4,4′‐diaminodiphenylmethane (DDM) were studied using dynamic mechanical analysis (DMA), Fourier‐transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). DMA studies show that the DDM‐cured TGDDM/PEK‐C blends have only one T_g. SEM observation also confirmed that the blends were homogeneous. FTIR studies showed that the curing reaction is incomplete due to the high viscosity of PEK‐C. As the PEK‐C content increased, the tensile properties of the blends decreased slightly and the fracture toughness factor also showed a slight decreasing tendency, presumably due to the reduced crosslink density of the epoxy network. SEM observation of the fracture surfaces of fracture toughness test specimens showed the brittle nature of the fracture for the pure ER and its blends with PEK‐C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 598–607, 2001     

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     

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     

Poly(arylene ether)s carrying pendant (3‐sulfonated) phenylsulfonyl groups

A series of poly(arylene ether)s with biphenyl units and pendant sulfonated phenylsulfonyl groups was prepared via nucleophilic aromatic substitution reactions of varying ratios of 3,5‐difluoro‐3′‐sulfonated diphenylsulfone and 4,4′‐difluorodiphenylsulfone with 4,4′‐biphenol. As such, the sulfonic acid moieties reside in the meta position of a pendant, electron‐poor phenylsulfonyl group. Mechanically robust proton‐exchange membranes with ion‐exchange capacities (IEC) ranging from 0.91 to 2.05 meq g^?1 were cast from dimethylacetamide. The thermal stability of the membranes was evaluated via thermogravimetric analysis and the 5% weight losses were found to be in excess of 330 °C in air. The glass transition temperatures were determined, via differential scanning calorimetry, to range from a low of 148 to a high of 209 °C at IEC values of 0.91 and 1.79 meq g^?1, respectively. The copolymer membranes reached proton conductivities as high as 142 mS cm^?1 under 100% relative humidity, with relatively low water uptake values (8–32 wt%). Copyright © 2012 Society of Chemical Industry     

Synthesis and characterization of poly(ether ketone ether ketone ketone)/poly(ether ether ketone ketone) copolymers containing naphthalene and pendant cyano groups

2,6‐Bis(β‐naphthoxy)benzonitrile (BNOBN) was synthesized by reaction of β‐naphthol with 2,6‐difluorobenzonitrile in N‐methyl‐2‐pyrrolidone (NMP) in the presence of KOH and K₂CO₃. Poly(ether ketone ether ketone ketone)(PEKEKK) /poly(ether ether ketone ketone) (PEEKK) copolymers containing naphthalene and pendant cyano groups were obtained by electrophilic Friedel‐Crafts polycondensation of terephthaloyl chloride (TPC) with varying mole proportions of 4,4′‐diphenoxybenzophenone (DPOBP) and 2,6‐bis(β‐naphthoxy)benzonitrile (BNOBN) using 1,2‐dichloroethane (DCE) as solvent and NMP as Lewis base in the presence of anhydrous AlCl₃. The resulting polymers were characterized by various analytical techniques, such as FTIR, DSC, TG, and WAXD. The results indicated that the crystallinity and melting temperature of the polymers decreased with increase in concentration of the BNOBN units in the polymer, the glass transition temperature of the polymers increased with increase in concentration of the BNOBN units in the polymer. Thermogravimetric studies showed that all the polymers were stable up to 536°C in N₂ atmosphere. The copolymers have good resistance to acidity, alkali, and organic solvents. Because of the melting temperature (T_m) depression with increase in the BNOBN content in the reaction system, the processability of the resultant coplymers could be effectively improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of thio‐containing poly(ether ether ketone)s

A series of thio‐containing poly(ether ether ketone) (PEESK) polymers was synthesized by the introduction of thio groups from 4,4′ thiodiphenol (TDP) into the poly(ether ether ketone) (PEEK) structure via reaction between the phenol and aromatic fluoride groups. The effect of the thio groups on the properties of the PEESK materials was investigated. Differential scanning calorimetry (DSC) analysis and X‐ray diffraction (XRD) patterns show a depression in the crystallinity of the PEESKs with incorporation of the content of thio groups in the backbones. The crystalline structure was identified as an orthorhombic structure with lattice constants of a = 7.52 Å, b = 5.86 Å and c = 10.24 Å for all crystallizable PEESKs. The crystalline structures of the thio‐containing PEEK polymers were the same as that of the neat PEEK, which means the thio‐containing block in the whole thio‐containing PEEK molecule is almost excluded from the crystalline structure and the crystals are completely formed by ‘non‐thio’ blocks only. Due to the glass transition temperature (T_g) and melting temperature (T_m) depression with increase in the TDP content in the reaction system, the processability of the resultant thio‐containing PEEKs could be effectively improved. Copyright © 2004 Society of Chemical Industry     

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     

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     

PWA/silica doped sulfonated poly(ether sulfone) composite membranes for direct methanol fuel cells

A novel sulfonated poly(ether sulfone) (SPES)/phosphotungstic acid (PWA)/silica composite membranes for direct methanol fuel cells (DMFCs) application were prepared. The structure and performance of the obtained membranes were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), water uptake, proton conductivity, and methanol permeability. Compared to a pure SPES membrane, PWA and SiO₂ doped membranes had a higher thermal stability and glass transition temperature (T_g) as revealed by TGA‐FTIR and DSC. The morphology of the composite membranes indicated that SiO₂ and PWA were uniformly distributed throughout the SPES matrix. Proper PWA and silica loadings in the composite membranes showed high proton conductivity and sufficient methanol permeability. The selectivity (the ratio of proton conductivity to methanol permeability) of the SPES‐P‐S 15% composite membrane was almost five times than that of Nafion 112 membrane. This excellent selectivity of SPES/PWA/silica composite membranes indicate a potential feasibility as a promising electrolyte for DMFC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Miscibility and phase behavior in blends of phenolphthalein poly(ether sulfone) and poly(hydroxyether of bisphenol A)

Miscibility and phase behavior in the blends of phenolphthalein poly(ether sulfone) (PES-C) with poly(hydroxyether of bisphenol A) (PH) were investigated by means of differential scanning calorimetry (DSC), high resolution solid state nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). It was found that the homogeneity of the as-prepared blends depended on the solvents used; N,N-dimethylformamide (DMF) provided the segmental mixing for PH and PES-C, which is confirmed by the behavior of single, composition-dependent glass transition temperatures (T_g's). To examine the homogeneity of the blends at the molecular level, the proton spin-lattice relaxation times in the rotating frame T_1ρ(H) were measured via ¹³C CP/MAS NMR spectroscopy as a function of blend composition. In view of the T_1ρ(H) values, it is concluded that the PH and PES-C chains are intimately mixed on the scale of 20-30 Å. FTIR studies indicate that there were the intermolecular specific interactions in this blends, involved with the hydrogen-bonding between the hydroxyls of PH and the carbonyls of PES-C, and the strength of the intermolecular hydrogen bonding is weaker than that of PH self-association. At higher temperature, the PH/PES-C blends underwent phase separation. By means of thermal analysis, the phase boundaries of the blends were determined, and the system displayed the lower critical solution temperature behavior. Thermogravity analysis (TGA) showed that the blends exhibited the improved thermal stability, which increases with increasing PES-C content.     

Nano‐AlN functionalization by silane modification for the preparation of covalent‐integrated epoxy/poly(ether imide) nanocomposites

Aluminum nitride nanoparticle (nano‐AlN) organically modified with the silane‐containing epoxide groups (3‐glycidoxypropyltrimethoxy silane, GPTMS) was incorporated into a mixture of poly(ether imide) (PEI), and methyl hexahydrophthalic anhydride‐cured bisphenol A diglycidyl ether grafted by GPTMS was prepared for nanocomposite. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to investigate the microscopic structures of nanocomposites. According to experimental results, it was shown that addition of nano‐AlN and PEI into the modified epoxy could lead to the improvement of the impact and bend strengths. When the concentrations of nano‐AlN and PEI were 20 and 10 pbw, respectively, the toughness/stiffness balance could be achieved. Dynamic mechanical analysis (DMA) results displayed that two glass transition temperatures (T_g) found in the nanocomposites were assigned to the modified epoxy phase and PEI phase, respectively. As nano‐AlN concentration increased, T_g value of epoxy phase had gradually increased, and the storage modulus of the nanocomposite at the ambient temperature displayed an increasing tendency. Additionally, thermal stability of the nanocomposite was apparently improved. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and resulted morphological structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Structural and mechanical characterization of poly(ether ether ketone) (PEEK) and sulfonated PEEK films: Effects of thermal history,sulfonation, and preparation conditions

In this work, virgin and sulfonated poly(ether ether ketone) films (PEEK and SPEEK, respectively) have been studied by dynamic mechanical analysis, modulated differential scanning calorimetry, wide‐angle X‐ray diffraction, birefringence, and optical microscopy. The properties of the unmodified polymer have been addressed to assess the original morphological characteristics and the changes induced by sulfonation. In general, the introduction of ionic groups in the polymer backbone alters dramatically the intrinsic properties of the parent material. The particular thermomechanical response exhibited by PEEK and SPEEK samples, characterized by a hysteresis loop, can be explained by the reversible and irreversible relaxation–orientation of the microstructure, even in the sub‐T_g region. The results showed that the preparation conditions largely determine the nonequilibrium morphological features of both compression‐molded PEEK films and solvent‐cast SPEEK membranes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 756–774, 2006     

Novel sulfonated poly(arylene biphenylsulfone ether) copolymers containing bisphenylsulfonyl biphenyl moiety: structural,thermal, electrochemical and morphological characteristics

A series of sulfonated poly(arylene biphenylsulfone ether) polymers containing up to two pendant sulfonic acid groups per repeat unit were successfully synthesized from 4,4′‐bis[(4‐chlorophenyl)sulfonyl]‐1,1′‐biphenyl (BCPSBP), disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenylsulfone (SDCDPS) and bisphenol A via aromatic nucleophilic displacement polycondensation. The resulting polymers were characterized by means of Fourier transform infrared and ¹H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis (TGA). The number‐average molecular weight (M_n) of the synthesized polymers was in the range 15 300–22 900 g mol^?1, and the polydispersity indices (M_w/M_n) varied from 2.5 to 4.4. Tough membranes with SDCDPS/BCPSBP mole ratio up to 50:50 were successfully cast using N‐methyl‐2‐pyrrolidone (NMP). An increase of sulfonic acid groups in the polymer backbone resulted in increased solubility in aprotic polar solvents and glass transition temperature. The TGA curves of all the copolymers in acid form exhibited two distinct weight‐loss profiles. The influential characteristics of the polymer electrolyte membranes, such as tensile strength, water uptake, ion‐exchange capacity and proton conductivity, were characterized with respect to the pendant sulfonic acid groups. Atomic force microscopy phase images of the acid‐form membranes clearly showed the hydrophilic domains, with sizes increasing as a function of the degree of sulfonation. Copyright © 2010 Society of Chemical Industry     

Glass‐transition temperature of poly(vinylidene fluoride)‐poly(methyl acrylate) blends: Influence of aging and chain structure

The glass‐transition temperature (T_g) of the poly(vinylidene fluoride) (PVF₂)‐poly(methyl acrylate) (PMA) blends increase with aging time. The T_g versus log(time) plots are straight lines whose slope values depend on the head to head (H–H) defect content of PVF₂ samples and on the composition of the blends. The values of polymer–polymer interaction parameters (χ) increase with an increase in the H–H defect of PVF₂ for a fixed composition of the blend. Consequently, the T_g of the blend decreases with an increase in the H–H defect of the PVF₂ sample. However, after aging for longer times this decrease of the T_g with H–H defects is lower than those of the unaged blends. The possible reasons are discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1541–1548, 2001     

Synthesis of multi‐block copolymer and its compatibilization to the blends of poly(ether ether ketone) with thermotropic liquid crystalline polymer

A multiblock copolymer (BCP) containing amorphous poly(aryl ether ketone) (PAEK) and thermotropic liquid crystalline polymer (TLCP) segments was synthesized. The chemical structure and properties of BCP were characterized by fourier‐transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC), gel permeation chromatograms (GPC), thermogravimetry analysis, polar light microscope (PLM), and solubility test respectively. BCP can dissolve in chloroform because of soluble PAEK block bonded with TLCP block, which was insoluble. The peak of the original PAEK oligomer was no more present in the GPC traces of the block copolymer. These facts indicated that polymer synthesized should be copolymers of the two components rather than blends. A single T_g at 138.1°C and broad melting endotherm at 315.7°C can be observed. The liquid crystalline texture of BCP showed uniformity in the view after heat treated for 10 min above its T_m under PLM. Ternary blends of poly(ether ether ketone) (PEEK)/TLCP/BCP were prepared by extrusion and characterized by DSC. DSC results showed that the crystallization temperature of PEEK phase in the blends shifted higher with the addition of TLCP. Wide angle X‐ray diffraction investigations indicated that the crystalline structure of PEEK was not disturbed by blending or compatibilizing. Scanning electron microscope and mechanical tests confirmed the compatibilizing effect of BCP. Reduction in dispersed phase TLCP size was observed when 2 phr by weight of compatibilizer was added to the blend. Measurement of the tensile properties showed increased elongation as well as improved modulus and strength to some extent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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.     

Blends of Poly(ether imide) and Styrene Sulfonic Acid Based Polymer: Thermal,Mechanical and Ionic Conduction Behavior

Dense membranes based on poly(ether imide) (PEI) and poly(styrene sulfonic acid-co-maleic acid) (PSSAMA) was obtained by extrusion and compression molding. Blends with different PSSAMA content (1, 3, 5, and 10 wt%) were prepared. Their morphology was investigated by scanning electron microscopy (SEM) and their thermal properties by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic-mechanical analysis (DMA). Two glass transition temperatures (T_g) (100 and 216°C) appeared when high contents of PSSAMA were added to PEI, indicating that the polymers form an immiscible system. TGA curves showed that the first weight loss occurred above 400°C for all blends, indicating a good thermal stability. Water uptake measurements have shown that the membranes presented low swelling when compared with Nafion®. The proton conductivity of the membrane with 10 wt% of PSSAMA obtained bv impedance measurements was 0.006 × 10^?2 S·cm^?1.