聚醚醚酮共混改性研究进展

综述了聚醚醚酮（PEEK）、聚醚酰亚胺（PEI）、聚四氟乙烯（PTFE）、热致液晶（TLCP）和聚醚砜（PES）等高性能工程塑料的共混改性研究进展,详细探讨了各种PEEK共混物的相容性、结晶行为、微观结构、热行为和力学性能等性能特征。PEEK与PEI在熔融和无定形状态下完全相容,常用于PEEK的结晶行为和微观结构的基础研究;与PTFE、TLCP、PES共混分别是提高PEEK的摩擦磨损性能、加工性能和热稳定性的有效手段。各种共混物的相容性好坏对其结晶行为和微观结构有重要影响,从而影响了共混物的力学性能。在此基础上,对PEEK共混改性领域进一步的研究方向和内容进行了讨论。     

Radiation-induced graft polymerization of functional monomer into poly(ether ether ketone) film and structure-property analysis of the grafted membrane

Radiation-induced graft polymerization of sulfo-containing styrene derivatives into crystalline poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer, so-called “super-engineering plastics”. Graft polymerization of the sulfo-containing styrene, ethyl 4-styrenesulfonate (E4S) into a high crystalline PEEK substrate (degree of crystallinity: 32%) hardly progressed, whereas graft polymerization into a low crystalline PEEK substrate (degree of crystallinity: 11%) gradually progressed, achieving a grafting degree of more than 50% after 72 h. Oxygen radicals appeared in the ESR spectra of irradiated PEEK films, indicating that graft polymerization initiates from the phenoxy radicals generated by scission of PEEK main chains and proceeds so as to yield block type grafts. The PEEK-based polymer electrolyte membrane (PEM) converted by aqueous hydrolysis of grafted films exhibited mechanical strength (100 MPa), being 88% of the original PEEK substrates. These mechanical properties of PEEK-based PEM are much higher than those of graft-type fluorinated PEM reported previously and almost three times higher than that of Nafion (35 MPa). Wide- and small-angle X-ray scattering (WAXS and SAXS) indicated that the graft polymerization was accompanied with recrystallization of the amorphous phase of PEEK substrate, the well known solvent-induced recrystallization of amorphous PEEK solids, to form a weak lamellar structure with 8 nm spacing. Complementary SAXS and small-angle neutron scattering (SANS) observations clearly showed that the graft-type PEEK membranes possessed ion channel domains with the average distance of 13 nm, being larger than that of Nafion. Furthermore, there was a micro-structure in the ion channels with the average distance of 1.8 nm.     

The influence of annealing on the crystallization and tribological behavior of MWNT/PEEK nanocomposites

In this study, annealing influence on crystallization and scratch behavior of neat and multi‐wall carbon nanotube (MWNT) reinforced poly(ether ether ketone) (PEEK) nanocomposites have been investigated. Crystallization behavior of normal and annealed samples was investigated by using differential scanning calorimeter (DSC). Scratch behavior of normal and annealed samples was investigated by using micro scratch tester. In DSC analysis, it was detected that, melting enthalpy of annealed neat PEEK was increased sharply when compared to neat PEEK. Melting enthalpies of annealed PEEK nanocomposites prepared with addition of up to 1 wt% MWNT were increased with a decreased trend. However, nanocomposites with higher contents of MWNTs (>1 wt%) were dramatically affected by annealing process and melting enthalpy decreased sharply. Friction coefficient values of “annealed MWNT reinforced PEEK composites” were found to be lower than “normal PEEK composites.” Annealing process affects scratch hardness of both annealed and MWNT reinforced PEEK. Annealed nanocomposites with various MWNT concentrations showed higher scratch hardness values than normal PEEK nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

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.     

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.     

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.     

Differential scanning calorimetry and infra-red crystallinity determinations of poly(aryl ether ether ketone)

The differential scanning calorimetry (d.s.c.) heating thermograms of 12 poly(aryl ether ether ketone) (PEEK) samples of varying degrees of crystallinity have been recorded. The relation found between the degree of crystallinity as determined by specific gravity measurements, and the melting enthalpy of the polymer, shows that recrystallization is occurring during a heating scan rate of 10°C min⁻¹. This implies that d.s.c. is not a convenient technique to assess PEEK crystallinity. The infra-red absorbance spectra of the same samples have also been examined in the range from 1030 to 880 cm⁻¹. The 965 cm⁻¹ band, up to now considered as indicative of the PEEK crystallinity, is shown to be practically independent of the degree of crystallinity above 15%. However, there is evidence to support the existence of a true i.r. crystalline band located at 947 cm⁻¹. It is also suggested that the 965 cm⁻¹ band is due to a normal vibration mode of a short segmental conformation, whose presence is favoured in the crystalline phase, but also in the amorphous zones nearest to the crystallite surface.     

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     

Hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK)

A procedure for obtaining high performance large internal diameter (ID; >1 mm) hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK) is presented. A simple mixture of isomers of diphenylphthalate is a good solvent for employing the thermal‐phase inversion process to obtain PEEK membranes. Obtaining large ID hollow fibers with substantial transmembrane flux requires sufficient melt strength during spinning to prevent excessive draw of the extruding fiber. The use of a second leachable polymer to the blend satisfies the conditions, and polysulphone (PS) is found to provide superior membranes relative to either poly(etherimide) (PEI) or poly(ether sulphone) (PES) as a second polymer. PEEK membranes obtained by this process yield better chemical resistance to a concentrated warm surfactant/oil solution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 175–181, 1999     

Mechanical properties of a cryogenically mechanically alloyed polycarbonate–poly(aryl ether ether ketone) system

The processing–property relationship of a model cryogenically mechanically alloyed polymer–polymer system [polycarbonate (PC) and poly(aryl ether ether ketone) (PEEK)] was investigated. PC and PEEK powders were cryogenically mechanically alloyed for 10 h, and the resulting two‐phase powder particles were processed into testable coupons with a miniature ram‐injection molder. The bulk mechanical properties of the coupons made from the mechanically alloyed powders and nonmechanically alloyed powders were investigated as a function of mechanical alloying and injection‐molding parameters. The injection‐molded coupons were mechanically tested in the three‐point‐bending mode. The results demonstrated that no measurable improvement was achieved in the energy to break, strain at failure, or failure strength in the coupons made from the mechanically alloyed materials in comparison with those of the coupons made from the nonmechanically alloyed powders. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1196–1202, 2003     

Preparation and properties of poly(ether ether ketone) composites reinforced by modified wollastonite grafting with silaneterminated poly(ether ether ketone) oligomers

Silane-terminated poly(ether ether ketone) oligomers were synthesized and grafted onto wollastonite (W) particles. The prepared grafted-wollastonite particles (g-W) were then incorporated into PEEK matrix via melt processing. Properties of the PEEK composites were investigated using differential scanning calorimetry (DSC), universal tester and rheometer. The researchers found the mechanical properties of the PEEK/g-W composites were markedly enhanced, complex viscosity of the PEEK/g-W composites increased, and both the peak crystallization temperature (T _c ) and crystalline fraction (χ _c ) of the PEEK composites with g-W were significant higher compared with those of the PEEK composites with W. It is our belief that these results are due to the strong interaction between the grafted-wollastonite particles and the PEEK matrix.     

Crystallization phenomena in the injection molding of poly ether ether ketone and its influence on mechanical properties

A basic experimental investigation of structure development in the injection molding of poly ether ether ketone (PEEK) is presented. It is shown that, dependent upon processing conditions, especially mold temperature, PEEK may be injection molded to form glassy or crystalline parts or parts consisting of intermediate structures such as a glassy surface and one with an internal crystalline link. In general, cold molds produce glassy parts and hot molds crystalline parts. This behavior is carefully characterized using optical microscopy, differential scanning calorimetry, and wide angle X-ray diffraction techniques. The mechanical properties of these injection molded parts is characterized as a function of the crystalline and glassy contents and types of structural gradients developed in the parts.     

Crystallization and structure-mechanical property relations in poly(aryl ether ether ketone) [PEEK]

In the development of advanced composite materials, the mechanical behavior of the matrix is of critical importance. The next generation of composite materials will be based on high modulus tough matrices, of which poly(aryl ether ether ketone) [hereinafter, referred to as PEEK] is one of the first crystalline thermoplastics to receive serious attention. As in all crystalline polymers, the matrix is itself a composite material whose properties depend significantly on the crystalline morphology developed during processing. In this contribution, the current understanding of crystallization in PEEK and its influence on mechanical properties is reviewed. Problems yet to be resolved are highlighted.     

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     

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.     

Solid state and mechanical properties of injection molded poly(ether ether ketone)/polyarylate blends

Blends of poly(ether ether ketone) (PEEK) and bisphenol-A polyarylate (PAr) were directly prepared during the plasticization step of an injection molding machine and their solid-state and mechanical behaviors were studied. Despite the fact that PEEK-rich blends were apparently miscible by differential scanning calorimetry (DSC), from the dynamic-mechanical analysis (DMTA) results all the blends were composed of (a) a crystalline PEEK phase, (b) a practically pure amorphous PEEK phase, and (c) a PAr-rich phase richer in PEEK as the PEEK content in the blends increased. Annealed blends showed a poor mechanical performance in the PAr-rich region, but the PEEK-rich blends showed additive modulus of elasticity and tensile strength, and ductility and impact strength values similar to those of the highest of the two pure components. All the as-molded low-crystalline blends presented a synergistic behavior in the modulus of elasticity, as well as, surprisingly, in ductility and impact strength in the intermediate and slightly majority PEEK compositions. The different mechanical response of the components in fine dispersed phases and in macroscopic tensile specimens may account for the observed results.     

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     

Preparation and characterization of high‐performance poly(ether ether ketone) fibers with improved spinnability based on thermotropic liquid crystalline poly(aryl ether ketone) copolymer

High‐performance poly(ether ether ketone) (PEEK) fibers were prepared by melt‐spinning in the presence of thermotropic liquid crystalline poly(aryl ether ketone) copolymer (FPAEKLCP). The rheological and mechanical properties, birefringence, orientation, and crystallization of the resulting PEEK/FPAEKLCP fibers were characterized by using a melt flow indexer, capillary rheometer, single fiber electronic tensile strength tester, polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD), respectively. The results indicate that the melt viscosity of PEEK significantly reduced by introducing FPAEKLCP, followed by the improvements in the spinnability and the quality of as‐spun fibers. The tensile properties of PEEK/FPAEKLCP fibers mainly depend on the content of FPAEKLCP, drawing temperature, drawing ratio, and annealing processes. Moreover, the tensile strength and modulus of PEEK/FPAEKLCP fibers are obviously higher than those of neat PEEK fibers under the same processing conditions. This should be attributed to an enhancement in the orientation and crystallization of PEEK compounded with FPAEKLCP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1406‐1414, 2013     

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