Micro‐ and ultrafiltration film membranes from poly(ether ether ketone) (PEEK)

Film membranes from the thermoplastic poly(ether ether ketone) (PEEK) have been extruded and tested for their microfiltration and ultrafiltration performance. High‐performance asymmetric membranes have been obtained by extruding polymer blends of PEEK, polysulphone, and a small molecule solvent mixture, and then by removing the polysulphone and solvent in a subsequent extraction step. The process for making ultrafiltration membranes differs from microfiltration membranes only in the relative blend components, and the temperature of the film pick‐up rolls. Processing parameters with important effects on the membrane performance have been identified. Microfiltration membranes are characterized by their pore‐size distributions and SEM, and ultrafiltration membranes by their rejection of bovine serum albumin, bubble point, and SEM. Composite membrane for nanofiltration utilizing the PEEK ultrafiltration membrane as a substrate performed similarly to a commercial membrane for the same purpose. This work details the best method for making PEEK film membranes published to date. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1146–1155, 1999     

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     

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     

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.     

Pore structure and properties of poly(ether ether ketone) hollow fiber membranes: influence of solvent‐induced crystallization during extraction

Poly(ether ether ketone) (PEEK) hollow fiber membranes were prepared by a thermally induced phase separation method with polyetherimide as diluent, and N‐methyl pyrrolidone (NMP), dichloromethane and a composite extractant composed of NMP, ethanolamine and water as extractant. The effects of the different solvents induced crystallization on the pore structure during extraction and the properties of the PEEK hollow fiber membranes were investigated in detail. The crystallization behaviors of the membranes were characterized by DSC and XRD. The effect of the extractants on the microscopic morphologies, pore structures, water fluxes and mechanical properties of the membranes were investigated. The results showed that the extraction ability of the composite extractant was the most significant, followed by NMP and dichloromethane. The crystallinity of the hollow fiber was 39.0% before extraction and was elevated to 39.2% after the extraction with NMP, 46.6% with dichloromethane and 46.7% with the composite extractant, which shows that dichloromethane and the composite extractant have strong ability to induce the crystallization of PEEK. The inner and outer surfaces of the membranes obtained after extraction by the composite extractant had the largest pore size and the highest surface porosity. The most probable pore diameter of the membranes obtained after extraction by NMP, dichloromethane and the composite extractant was 23.26 nm, 24.43 nm and 24.43 nm, respectively, which indicated that solvent‐induced crystallization was beneficial for the formation of larger pores. The pure water flux of the PEEK membrane prepared by the composite extractant was the largest, but the tensile strength was the lowest. © 2019 Society of Chemical Industry     

聚醚醚酮纤维的发展现状与应用

综述了国内外聚醚醚酮(PEEK)纤维的研究发展现状;分析了制约我国PEEK纤维发展的原因;介绍了PEEK树脂的流变性能、纺丝技术;阐述了PEEK纤维的结构、物理化学性能及应用领域;提出我国应加大PEEK原料及其纤维的研发,实现PEEK纤维国产化。     

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。     

Tribological properties of micron silicon carbide filled poly(ether ether ketone)

The composite of poly(ether ether ketone) (PEEK) filled with micron silicon carbide (SiC) with different filler proportions was prepared by compression molding. The friction and wear properties of the composite were investigated at ambient conditions on a block on ring machine by running a plain carbon steel (AISI 1045 steel) ring against the composite block. The morphologies of the worn composite surfaces and the transfer film on the counterpart steel ring were examined with scanning electron microscopy and electron probe microanalysis. The results showed that the friction and wear of PEEK was slightly reduced at a filler proportion of micron SiC of 2.5–5.0 wt %. Abrasive wear was dominant for the PEEK composite; this was especially so at higher filler proportion. Meanwhile, abrasion and transfer to the composite surface of the counterpart steel ring were also observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2611–2615, 1999     

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     

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.     

Crystal structure and drawing‐induced polymorphism in poly(aryl ether ether ketone). IV

A new crystal modification induced by strain and denoted as form II exists alongside the dominant form I structure in the uniaxially oriented poly(ether ether ketone) (PEEK) and the related polymers. The crystal structure of form II for PEEK is also found to possess a two‐chain orthorhombic packing with unit cell parameters of a equal to 0.475 nm, b equal to 1.060 nm, and c equal to 1.086 nm. More extended and flattened chain conformation of form II relative to that of form I is expected to account for an 8% increase in c‐axis dimension, which is attributed to the extensional deformation fixed in situ through strain‐induced crystallization during uniaxial drawing. Annealing experiments suggest that form II is thermodynamically metastable and can be transformed into more stable form I by chain relaxation and reorganization at elevated temperature without external tension. This strain‐induced polymorphism exists universally in the poly(aryl ether ketone) family. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 237–243, 1999     

Characteristics of poly(ether ether ketone) microporous membranes prepared via thermally induced phase separation (TIPS)

The morphology and bulk properties of microporous membranes based on poly (ether ether ketone) (PEEK) have been investigated as a function of initial casting composition and thermal and mechanical processing history. Membranes were prepared via solid—liquid phase separation of miscible blends of PEEK and polyetherimide (PEI), with subsequent extraction of the PEI diluent. Scanning electron microscopy studies revealed a microporous morphology with two distinct pore size scales corresponding to diluent extraction from interfibrillar and interspherulitic regions, respectively. The membrane structure was sensitive to both initial blend composition and crystallization temperature, with the resulting pore size distribution reflecting the kinetics of phase separation. For membranes prepared with lower initial diluent content or at lower crystallization temperatures, mercury intrusion porosimetry indicated a relatively narrow distribution of fine interfibrillar pores, with an average pore size of approximately 0.04 microns. Membranes prepared at higher diluent content or at higher crystallization temperatures displayed a broad pore distribution, with a sizeable population of coarse, interspherulitic pores (0.1 to 1 μm in size). Uniaxial drawing led to a fibrillated network structure with markedly higher water flux characteristics compared to the as-cast membranes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2347–2355, 1997     

复合成盐剂对聚醚醚酮合成与性能的影响

采用4,4′-二氟二苯甲酮、对苯二酚为原料,以不同比例的碳酸钾和碳酸钠为复合成盐剂,二甲苯为脱水剂,二苯砜为溶剂成功制备了一系列聚醚醚酮(PEEK)树脂。通过傅里叶红外光谱和X射线衍射对PEEK树脂结构进行了表征,证明合成的样品是对苯二酚型PEEK树脂。其次,对所制样品分别进行力学性能、特性黏度、热性能测试,详细地探讨不同钾/钠比例的复合成盐剂对PEEK性能的影响。结果表明,所有样品均展示了优异的力学性能和热性能,其熔点和初始分解温度分别大于330℃和520℃,拉伸强度介于77~101 MPa。此外,当碳酸钾和碳酸钠的物质的量比为7∶3时,PEEK树脂的综合性能达到最优。     

Preparation of honeycomb films from nitryl poly(ether ether ketone)s via water‐droplet templating

The fabrication of honeycomb‐patterned films from nitryl poly(ether ether ketone)s (PEEK‐NO₂) in a high‐humidity atmosphere was reported in this article. PEEK‐NO₂ was prepared through acid (nitric acid and sulfuric acid) nitration from poly(ether ether ketone)s (PEEK). The obtained polymer, which was characterized by Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and differential scanning calorimetry (DSC) showed excellent solubility and thermal stability. Some influence factors on the pattern formation and the fabrication of the porous structure, such as the solution concentration, the solvent, and the atmosphere humidity, were investigated. The results showed that with the increase of the solution concentration, the aperture of the film diminished gradually; the lower the solvents´ boiling point were, the smaller the films´ apertures were and the more regular the pores´ arrange; only under high‐humidity circumstances could obvious and ordered honeycomb films be formed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

聚醚醚酮表面壳聚糖的固定

通过紫外光接枝和湿化学法连用在聚醚醚酮 （PEEK）表面固定上具有抑菌杀菌作用的壳聚糖。结果表明,相比未改性的PEEK表面,改性后材料表面亲水性提高;通过扫描电子显微镜和X射线光电子能谱分析证明壳聚糖成功接枝在了PEEK薄膜表面;随着壳聚糖浓度的提高,材料表面的壳聚糖接枝率增加。     

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     

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.     

Novel copoly(ether ether ketone)s with pendant phenyl groups: synthesis and characterization

In order to obtain poly(ether ether ketone)s having enhanced solubility and processability without extreme loss of other properties, a series of copoly(ether ether ketone)s (Co‐PEEKs) with pendant phenyl groups were synthesized from 1,1‐bi(4‐hydroxyphenyl)‐1‐phenylethane (ph‐BPA), hydroquinone and 4,4′‐difluorobenzophenone via aromatic nucleophilic substitution reaction. The structures and properties of the Co‐PEEKs were characterized using Fourier transform infrared and ¹H NMR spectroscopies, differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction and solubility testing. These Co‐PEEKs have inherent viscosities in the range 0.14–1.09 dL g^?1, and their number‐average and weight‐average molecular weights reach 72 659 and 163 400 g mol^?1, respectively. The Co‐PEEK with the lowest content of ph‐BPA has a semi‐crystalline nature and is only soluble in 98% sulfuric acid. However, with an increase of ph‐BPA in the Co‐PEEKs, they become amorphous and readily soluble in a wide range of organic solvents and can afford tough films. These Co‐PEEKs have glass transition temperatures of 137–180 °C depending on the content of ph‐BPA. All the Co‐PEEKs have initial degradation temperatures above 480 °C in nitrogen atmosphere. Thus, these Co‐PEEKs with excellent thermal stability, good solubility and processability have potential for use in high‐performance films, coatings, hollow fiber membranes, etc. Copyright © 2011 Society of Chemical Industry     

Permeation resistance of poly(ether ether ketone) to hydrogen,nitrogen, and oxygen gases

We studied the gas permeation properties of poly(ether ether ketone) (PEEK) and compared it with two other polymers commonly used in the construction of semiconductor microenvironments, polycarbonate (PC), and poly(ether imide) (PEI). The PEEK specimens consisted of extruded films as well as compression‐ and injection‐molded specimens. The compression‐molded specimens were prepared to achieve the highest crystallinity. Injection‐molded disks, representing products, were milled to a prescribed thickness. Permeation, diffusion, and solubility coefficients were measured on these various PEEK specimens for hydrogen, nitrogen, and oxygen gases. It was found that PEEK generally has better permeation resistance than PC or PEI; showing up to five times lower permeation rates than PC or PEI, depending on grade, crystallinity, and gas. The superior permeation resistance of injection‐molded or extruded PEEK, when compared with similarly processed PC or PEI, comes from its crystallinity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effect of crystallinity on the scratch hardness of poly(ether ether ketone)

Summary This paper describes a study of the surface properties of the poly(ether ether ketone) (PEEK) using a scratch hardness technique. A comparison of the hardness values determined for amorphous and crystalline PEEK shows that the crystalline polymer is harder. In addition, comparison of the scratch frictional behaviour indicates several friction mechanisms apply for this polymer.