Toughening of Diglycidyl Ether of Bisphenol-A Epoxy Resin Using Poly (Ether Ether Ketone) with Pendent Ditert-Butyl Groups

Poly(ether ether ketone) (PEEKDT), hydroxyl terminated poly(ether ether ketone) (PEEKDTOH) and fluorine terminated poly (ether ether ketone) (PEEKDTF) with pendent ditert-butyl groups were synthesized by the nucleophilic substitution reaction of 4,4′-difluorobenzophenone with 2,5-ditert-butylhydroquinone in N-methyl-2-pyrrolidone medium using anhydrous potassium carbonate as catalyst. Diglycidyl ether of bisphenol-A epoxy resin was blended with PEEKDT, PEEKDTOH, and PEEKDTF, and cured with 4,4′-diaminodiphenylsulfone (DDS). The polymers formed heterogeneous blends before curing, and upon curing the polymers got dispersed in the epoxy matrix. The mechanical properties of the cured blends were slightly lower than that of the unmodified resin. The fracture toughness increased with the addition of ditert-butyl PEEK into epoxy resin and the extent of improvement was dependent on the type of modifier used. Hydroxyl terminated polymers gave up to 40% increase in fracture toughness. The dynamic mechanical spectrum of the blends showed only a single T_g due to the proximity of the glass transition temperature of modified PEEK and DDS cured epoxy resin.     

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 of poly(ether ether ketone)-block-polyimide copolymer and its compatibilization for poly(ether ether ketone)/thermoplastic polyimide blends

Novel poly(ether ether ketone)-block-polyimide copolymers (PEEK-b-PI) with different block length were prepared by the polycondensation of amino-terminated poly(ether ether ketone) oligomer and anhydride-terminated polyamic acid oligomer. As the compatibility agent, PEEK-b-PI was added to the poly(ether ether ketone)/thermoplastic polyimide (PEEK/TPI) blend, and blends of PEEK/TPI/PEEK-b-PI were prepared by melt extrusion. Morphology observation showed the domain size of the dispersed phase was significantly reduced with the addition of PEEK-b-PI having optimized block length, which suggested reduced interfacial tension and enhanced interfacial adhesion. The compatibilizing effect was further proven by the change of the glass transition temperature of PEEK and TPI, which shifted closer to each other. As a result, the mechanical properties of PEEK/TPI blends were significantly improved with the addition of the PEEK-b-PI. In particular, 5 wt% content of PEEK-b-PI can increase the elongation at break of the blend by about 200%.     

高性能聚芳醚酮的发展及应用

综述了聚醚酮、聚醚醚酮、聚醚醚酮酮、聚醚酮酮、聚醚酮醚酮酮等5类高性能聚芳醚酮的性能、合成方法及其改性研究进展等,并介绍了聚芳醚酮的应用情况,指出聚芳醚酮的发展趋势是通过开发新的合成技术或者改性途径,在不影响其主要性能的前提下降低生产成本.     

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     

Hydroxyl terminated poly(ether ether ketone) with pendent methyl group toughened epoxy resin: miscibility, morphology and mechanical properties

The synthesis, processing, thermal and mechanical properties and fracture toughness of epoxy resin formulated with hydroxyl terminated poly(ether ether ketone) with pendent methyl group are reported. Hydroxyl terminated poly(ether ether ketone) oligomers based on methyl hydroquinone (PEEKMOH) were synthesised from methylhydroquinone and 4,4′-difluorobenzophenone in N-methyl-2-pyrrolidone. PEEKMOH oligomers with different molecular weights were synthesised and characterised. Blends of diglycidyl ether of bisphenol-A epoxy resin with PEEKMOH were prepared by melt mixing. The uncured blends were homogeneous and the T_g-composition behaviour was predicted using Fox, Gordon–Taylor and Kelley–Bueche equations. Reaction induced phase separation occurred in the blends on curing with 4,4′-diaminodiphenyl sulfone. Scanning electron microscopy studies revealed the two-phase morphology of the blends. Domain size of the blends increased with increase in PEEKMOH8 in the blends. Phase separation in the blends occurred by nucleation and growth mechanism. Infrared spectroscopic studies revealed that some of the epoxy groups were opened up by hydroxyl group of PEEKMOH. The tensile and flexural properties of the blends were comparable to that of neat epoxy resin and the properties were dependent on the composition of the blend and molecular weight of PEEKMOH used. Dynamic mechanical analysis revealed two glass transition temperatures corresponding to epoxy rich and thermoplastic rich phases. The crosslink density of epoxy resin decreased with the addition of PEEKMOH to epoxy resin. The blends exhibited superior fracture toughness compared to unmodified epoxy resin. The increase in fracture toughness was due to local plastic deformation of the matrix, crack path deflection and crack pinning. The thermal stability of amine cured epoxy resin was not affected by the incorporation of PEEKMOH into the epoxy resin.     

Miscibility and mechanical properties of poly(ether imide)/poly(ether ether ketone)/liquid crystalline polymer ternary blends

This paper is concerned with a novel ternary blend composed of poly(ether imide) (PEI), poly(ether ether ketone) (PEEK) and a liquid crystalline polymer (LCP; HX4000, Du Pont). Different compositions were prepared by extrusion and injection moulding. Dynamic mechanical thermal analysis and the observation of the fracture surfaces, before and after annealing, allowed determination of the cold crystallization temperatures and miscibility behaviour of these systems. PEEK/PEI blends are known from previous studies to be miscible at all compositions. In this case it was observed that the PEEK/HX4000 blend was miscible up to 50 wt% HX4000 but partially miscible above this value. The PEI/HX4000 blends were found to be partially miscible in the whole concentration range. As a result, some ternary blend compositions exhibited only one phase, while others exhibited two phases. The measurement of the tensile properties showed that ternary blends with high modulus can be obtained at high LCP loadings, while compositions with high ultimate tensile strength can be obtained with high loadings of PEI or PEEK.     

Crystallization behavior and mechanical properties of poly(aryl ether ether ketone)/poly(ether imide) blends

Crystallinity and mechanical properties of blends with different amounts of semicrystalline poly(aryl/ ether ether ketone) (PEEK) and amorphous poly(ether imide) (PEI) polymers have been studied. The blends, prepared by melt mixing, have been investigated by differential scanning calorimeter (DSC) to analyze the miscibility between the components and the final crystalline content. Moreover, for the 20/80 PEEK/PEI blend, crystallization in dynamic and isothermal conditions has been carefully investigated in order to find proper conditions for maximum development of crystallinity. Mechanical tests (static and dynamic) have been performed to evaluate the properties of the as-molded and crystallized blends and to compare them with those of crystalline PEEK and amorphous PEI neat resins. Finally, a few SEM observations have been performed to compare the fractured surface of the blend with those of the pure constituents.     

Miscible blends of poly(aryl ether ketone)s and polyetherimides

A new class of high performance engineering resins, poly(aryl ether ketone)s, has emerged with a property balance not offered by existing polymeric materials. Blends of poly(aryl ether ketone)s with other polymers have not been described in the open literature, although several patents have revealed interesting and important properties of certain blend combinations. Ultem polyetherimide has been found to be miscible over the entire composition range and as a consequence is a very effective heat distortion temperature builder, particularly if the poly(aryl ether ketone) is allowed to crystallize. Crystallization kinetics and mechanical properties were studied as a function of blend composition and poly(aryl ether ketone) melting point. The blends exhibited a maximum in toughness at intermediate compositions along with an accompanying maximum in poly(aryl ether ketone) crystallinity. The chemical resistance of the polyetherimide is significantly improved with the addition of a poly(aryl ether ketone). In organic chemicals, the improvement was expected when tensile stress was plotted vs. log time to rupture. However, in aqueous bases, the resistance of the blends was much greater than anticipated. This property profile suggests that these blends will be useful as thermoplastic composite matrix resins.     

Mechanical properties of poly(ether ether ketone)/poly(ether ketone) blends: Use of simple models relating normalized tensile parameters

In this study, mechanical properties such as tensile properties, flexural properties, and Izod impact strength of poly(ether ether ketone) (PEEK) and poly(ether ketone) (PEK) blends at PEK concentration from 0 to 0.42 volume fraction were studied. The blends of PEEK and PEK of different compositions were prepared by extrusion in a single‐screw extruder. With increase in the PEK concentrations, the tensile strength, flexural strength, and modulus increased whereas the tensile modulus and the impact strength decreased. Homogeneous dispersion and adhesion of PEK in PEEK was shown by the morphological studies. Crystallinity of blends influenced the tensile modulus and the impact strength. Using simple models to relate normalized tensile parameters where the data were divided by the crystallinity of the blends and of the PEEK matrix, respectively, supported the experimental results. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(ether ether ketone)/poly(aryl ether sulfone) blends: Relationships between morphology and mechanical properties

Mechanical properties such as the tensile modulus, yield (break) strength, and elongation to break (or yield) are measured for multiphase poly(ether ether ketone) (PEEK)/poly(aryl ether sulfone) (PES) blends. Specimens with three different levels of thermal histories (quenched, as‐molded, and annealed) are prepared in order to study their effects on the mechanical properties of PEEK/PES blends. Synergistic behavior is observed in the tensile modulus and tensile strength of the blends in almost the whole range of compositions. The ductility of quenched blends measured as the elongation to break (yield) shows an unexpected synergistic behavior in the blend containing 90 wt % PEEK, although a negative deviation from additive behavior is observed in the rest of the compositions. A ductile–brittle transition is observed between 50 and 75 wt % PEEK in the blend. The ductile–brittle transition in as‐molded blends shifts to 75–90 wt % PEEK. Annealed blends show predominantly brittle behavior in the whole composition range. The experimental data are further correlated with the theoretically predicted results based on various composite models. Although the prediction based on these equations fails to fit the experimental data in the whole composition range, the simplex equations that are normally used for blends showing synergistic behavior produced a reasonable fit to the experimental data. The mechanical properties obtained for different blend compositions are further correlated with their morphology as observed by scanning electron microscopy. Morphological observation shows a two‐phase morphology in PES‐rich blends, which is an interlocked morphology in which the disperse phase is not clearly visible in PEEK‐rich blends, and a cocontinuous type of morphology for a 50/50 composition. Considerable permanent deformation of both the disperse and matrix phase, especially in the case of quenched tensile specimens, demonstrates the remarkable adhesion present between the two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2887–2905, 2003     

Mechanical and Thermal Properties of Poly(phthalazinone biphenyl ether sulfone)/PEEK Blends

A series of blends with various compositions are prepared by melt extrusion on the basis of novel copoly(phthalazinone biphenyl ether sulfone) (PPBES) and poly(ether ether ketone) (PEEK). The melt flowability, mechanical and thermal properties of the blends are studied. The results show that the incorporated PEEK has a large influence on the melt viscosity and thermal stability of blends. The tensile strength of the blends remains at about 90 MPa at room temperature; PPBES improves the mechanical properties of PEEK at 150°C. The flexural strength and modulus of the PPBES/PEEK blends also increase with the addition of PEEK.     

Morphology,viscoelastic properties,and mechanical behavior of epoxy resin modified with hydroxyl‐terminated poly(ether ether ketone) oligomer with pendent tert‐butyl groups

Hydroxyl‐terminated poly (ether ether ketone) with pendent tert‐butyl groups (PEEKTOH) synthesized from 4,4′‐difluorobenzophenone and tert‐butyl hydroquinone was blended with diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin. A diamine, 4,4′‐diaminodiphenyl sulfone (DDS) was used as the curing agent. The thermal and mechanical properties, fracture toughness, and morphology of the blends were investigated. Morphological analysis of the blends revealed a particulate structure with PEEKTOH phase dispersed in the epoxy matrix. Unlike classical polymer blend systems, increase in concentration of PEEKTOH does not increase the domain size. Instead, a decrease is obtained. The fracture toughness increased with the addition of oligomer without much decrease in tensile and flexural strengths. Addition of 15 phr oligomer gave maximum toughness. The dispersed PEEKTOH initiated several mechanisms that improved the fracture toughness of the blends. The cross‐link density calculated from the storage modulus in the rubbery plateau region decreased with the increase in PEEKTOH. The thermal stability of epoxy resin remained unaffected even after blending with PEEKTOH. POLYM. ENG. SCI., 45:1645–1654, 2005. © 2005 Society of Plastics Engineers     

Enhancing resistance of poly(ether ketone ketone) to high-temperature steam through crosslinking and crystallization control

Poly(aryl ether ketone)s (PAEKs) are promising materials for harsh environments, such as in high-temperature steam applications. Here, the effect of high-temperature steam on the crystallinity and mechanical properties of existing poly(ether ether ketone) (PEEK) and PEKK(T/I) polymers is investigated. Differential scanning calorimetry (DSC), wide-angle X-ray scattering or diffraction (WAXD), and dynamic mechanical analysis experiments show these materials undergo significant crystallization and reorganization after prolonged exposure to steam and suffer from embrittlement. In addition, we show that xanthydrol-based crosslinks can provide the dimensional stability and stabilize the PEKK crystal structure. Mechanical tests demonstrate that the ductility is preserved for longer exposures to steam compared to neat PEKK, whereas DSC and WAXD data indicate xanthydrol crosslinks effectively stabilize the crystal structure against steam-assisted crystallization. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47727.     

High-temperature steam-treatment of PBI,PEEK, and PEKK polymers with H2O and D2O: A solid-state NMR study

Polyaryletherketones (PAEK) in blend systems with polybenzimidazoles (PBI) are of commercial interest due to their increased service temperature and reduction in abrasive wear against soft counterfaces when compared to PAEK alone. ASTM standard tensile specimens of PBI, polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) are immersed in stirred D₂O at room temperature, and additional samples are contacted with D₂O steam at temperatures of 150 and 315 °C. All samples are studied by TGA, IR, ¹³C CP/MAS, ¹H wideline, and ²H MAS NMR. Changes in the physical appearance of the samples and the extent of D₂O uptake are described. Different locations, mobilities, and types of water and protons in the polymers are identified and studied and it is proven that PBI contains the largest amounts of D₂O after exposure under all conditions. PEEK and PEKK only incorporate minimal amounts of D₂O even when steam-treated at 315 °C.     

Nanocellular foams—cell structure difference between immiscible and miscible PEEK/PEI polymer blends

Plastic foam with a nanoscale cell structure was prepared from poly(ether ether ketone) (PEEK)/para‐diamine poly(ether imide) (p‐PEI) as well as PEEK/meta‐diamine poly(ether imide) (m‐PEI) blends by a temperature quench foaming method with CO₂. The difference in chemical configuration between m‐ and p‐PEI gave rise to a prominent change in the higher order blend morphology and cell structure of the respective foams. The bubble nucleation site and bubble size were controlled by templating the morphology of the PEEK/p‐PEI blend, which shows an immiscible and unique strip‐patterned crystalline morphology. The properties influenced by the immiscibility of the PEEK/p‐PEI blend were investigated using SEM, thermal analysis and rheology and compared with the properties of the miscible PEEK/m‐PEI blend. The bubble size and location were highly controlled in the PEI disperse domain that was aligned between the PEEK crystalline layers in the PEEK/p‐PEI blend. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

End‐functionalized thermoplastic‐toughened phthalonitrile composites: influence on cure reaction and mechanical and thermal properties

Phthalonitrile polymers are known for their high thermal stability and good mechanical properties. However, their brittle nature limits their application as structural composites in many critical areas. The present study investigates the feasibility of toughening novolac–phthalonitrile (NPN) resin using chemically modified poly(ether ether ketone) (PEEK). A telechelic PEEK bearing a phthalonitrile end group (PEEKPN) was synthesized via nucleophilic substitution of nitrophthalonitrile with the corresponding phenol–telechelic poly(ether ether ketone) (PEEKOH). Different compositions of NPN and PEEKOH–PEEKPN blends with curing agent, i.e. diaminodiphenylsulfone, were investigated for their cure behaviour and mechanical properties of their carbon fabric composites. In NPN–PEEKOH blends, crosslinking of the phthalonitrile groups was facilitated by phenol‐mediated reactions resulting in the reduction of cure temperatures by around 130 °C with substantial improvement in thermal stability. Blending the resin with the thermoplastic enhanced the mechanical properties of the composites. The apparent flexural strength and impact strength of carbon fabric‐reinforced composites were improved by more than 200 and 150%, respectively, on incorporation of 20 wt% PEEKOH in the NPN matrix. However, higher concentration of PEEKOH had a detrimental effect on the properties. Substitution of phenol end groups by phthalonitrile moieties led to integration of the PEEK moieties with the NPN matrix. However, it was not as conducive as PEEKOH for improving the matrix properties. The better performance of PEEKOH is attributed to the formation of polar heterocyclic groups like isoindoline by way of the phenol–nitrile reaction. © 2014 Society of Chemical Industry     

Investigation on the crystallization behavior of poly(ether ether ketone)/poly(phenylene sulfide) blends

The morphology of nonisothermally crystallized poly(phenylene sulfide) (PPS) and its blend with poly (ether ether ketone) (PEEK) have been observed by polarized optical microscope (POM) equipped with a hot stage. The nonisothermal crystallization behavior of PPS and PEEK/PPS blend has also been investigated by differential scanning calorimetry (DSC). The maximum crystallization temperature for PEEK/PPS blend is about 15°C higher than that of neat PPS, and the crystallization rate, characterized by half crystallization time, of the PEEK/PPS blend is also higher than that of the neat PPS. These results indicate that the PEEK acts as an effective nucleation agent and greatly accelerates the crystallization rate of PPS. The Ozawa model was used to analyze the nonisothermal crystallization kinetics of PPS and its blends. The Avrami exponent values of neat PPS are higher than that of its blend, which shows that the presence of PEEK changed the nucleation type of PPS from homogeneous nucleation to heterogeneous nucleation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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.     

Multinuclear solid‐state NMR investigation of the moisture distribution in PEEK‐PBI and PEKK‐PBI blends

Blends of polyaryletherketones (PAEK), such as polyetheretherketones (PEEK) and polyetherketoneketones (PEKK), with polybenzimidazole (PBI) are of commercial interest due to their improved high‐temperature stability and wear properties. The changes of PBI and its PEEK‐ and PEKK‐blends (50 : 50 wt %) after immersing them in liquid H₂O and D₂O, and exposing them to D₂O steam at elevated temperatures and pressures are investigated by multinuclear solid‐state NMR and IR spectroscopy. Macroscopic morphological and chemical changes on the molecular scale, which take place upon high‐temperature steam‐treatment and the extent and reversibility of moisture uptake have been investigated. Interactions and reactions of water, steam, and aqueous solutions of LiCl and ZnBr₂ with the functional groups of the polymer components have been studied using D₂O in combination with IR, ¹H wideline, ²H, ⁷Li, and ⁷⁹Br MAS, as well as ¹³C and ¹⁵N CP/MAS NMR spectroscopy. Different locations and types of water and protons in the blends have been described and PBI has been proven to be mainly responsible for water and salt uptake into the blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41421.