Hydrophilic interaction chromatography of intact, soluble proteins

The separation of intact proteins by means of Hydrophilic Interaction Chromatography (HILIC) was demonstrated with human apoA-I, recombinant human apoM, and equine cytochrome C. Five different commercially available HILIC columns were compared. Using one of these columns, different glycosylated isoforms of apoM were separated from each other and from the aglyco-form.     

Study on the Friction and Wear Properties of PEEK against Cortical Bone Tissue Under Different Lubricating Conditions

The tribological behavior between orthopedic implants and cortical bone is important but usually neglected. Poly(ether-ether-ketone) (PEEK) is a promising material for orthopedic applications. To further understand and improve the interfacial tribological properties between PEEK implant and host bone tissue, a PEEK-cortical bone tribo-pair is designed and fabricated. The frictional and wear performance of such tribo-pair is investigated under different lubricants, i.e., simulated body fluid (SBF), calf serum (CS), hyaluronic acid (HA), and mucin (MUC). The results suggest that MUC solution can be utilized as an artificial natural synovial fluid to improve the tribological properties of PEEK-based implants.     

Reinforced Modification of PEEK and its Applications

聚醚醚酮（PEEK）作为一种特种热塑性工程塑料,在许多工程领域有着广泛的应用。采用不同手段改性聚醚醚酮,改善其热学性能、力学性能、摩擦学性能和加工性能等,有利于降低生产成本和进一步拓展其应用范围。本文从化学改性和纤维增强、无机填充、表面改性、与有机共混等物理改性两个方面综述了近年来国内外聚醚醚酮改性研究进展情况,以及对其在工业领域、电子电器领域、航空领域、汽车领域和医学领域中的应用作了简单的概括,最后展望了聚醚醚酮改性研究开发问题及解决方法。     

Poly(etheretherketone)-turnings a novel sorbent material for lead determination by flow injection flame atomic absorption spectrometry and factorial design optimization

A novel hydrophobic sorbent material for on-line column preconcentration and separation systems coupled with atomic spectrometry was developed. Poly(etheretherketone) (PEEK) in the form of turnings was used as packing material and evaluated for trace lead determination in environmental samples. Sample and ammonium diethyl-dithiophosphate (DDPA) reagent were mixed on-line and the Pb(II)-DDPA complex was retained effectively on PEEK-turnings. Isobutyl methyl ketone (IBMK) was adopted for efficient analyte complex elution and subsequently transportation into the nebulizer-burner system for atomization. The developed sorbent material has shown, excellent chemical and mechanical resistance, fast adsorption kinetics permitting the use of high sample flow rates without significant loss of retention efficiency. For 120 s sample preconcentration time the sampling frequency was 20 h⁻¹, the enhancement factor was 110, the detection limit (3 s) was c_L = 0.32 μg L⁻¹, and the relative standard deviation (RSD) was s_R = 2.2%, at the 50.0 μg L⁻¹ Pb(II) level. The accuracy of the developed method was evaluated by analyzing certified reference materials.     

Structure–tribological property relationship of nanoparticles and short carbon fibers reinforced PEEK hybrid composites

In a previous work, the roles of low‐loading, that is, 1 vol %, nano‐SiO₂ particles on the tribological behavior of short carbon fibers (SCFs)/polytetrafluoroethylene (PTFE)/graphite filled polyetheretherketone (PEEK) were studied. In the present work, the effects of nanoparticle content, varying from 1 to 4 vol %, on the structure and the tribological performance of the composite was investigated. The polished cross sections of the composites were inspected using a scanning electron microscope (SEM). The incorporated nanoparticles significantly reduce the friction coefficients of the composite. With low pressure‐sliding velocity (pv) factors, nanoparticle agglomerates seem to exert an abrasive effect on SCF, and thereby lead to high wear rates. Under such conditions, an increase in nanoparticle content decreases the wear resistance. With high pv factors, the nanoparticles remarkably improve the wear resistance of the composite and the nanoparticle contents do not play an important role on the wear resistance. The worn surfaces, transfer films and wear debris of the composites were analyzed. The tribological mechanisms were discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 801–811, 2010     

Vitrification/devitrification phenomena during isothermal and nonisothermal crystallization of poly(aryl–ether–ether–ketone) (PEEK) and PEEK/poly(ether–imide) blends

We have established time–temperature transformation and continuous-heating transformation diagrams for poly(ether–ether–ketone) (PEEK) and PEEK/poly(ether–imide) (PEI) blends, in order to analyze the effects of relaxation control on crystallization. Similar diagrams are widely used in the field of thermosetting resins. Upon crystallization, the glass transition temperature (T_g) of PEEK and PEEK/PEI blends is found to increase significantly. In the case of PEEK, the shift of the α-relaxation is due to the progressive constraining of amorphous regions by nearby crystals. This phenomenon results in the isothermal vitrification of PEEK during its latest crystallization stages for crystallization temperatures near the initial T_g of PEEK. However, vitrification/devitrification effects are found to be of minor importance for anisothermal crystallization, above 0.1°C/min heating rate. In the case of PEEK/PEI blends, amorphous regions are progressively enriched in PEI upon PEEK crystallization. This promotes a shift of the α-relaxation of these regions to higher temperatures, with a consequent vitrification of the material when crystallized below the T_g of PEI. The data obtained for the blends in anisothermal regimes allow one to detect a region in the (temperature/heating rate) plane where crystallization proceeds in the continuously close proximity of the glass transition (dynamic vitrification). These experimental findings are in agreement with simple simulations based on a modified Avrami model coupled with the Fox equation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 919–930, 1998     

Molecular dynamics in ion‐irradiated poly(ether ether ketone) investigated by two‐dimensional correlation dielectric relaxation spectroscopy

This paper reports the first use of temperature–temperature 2D correlation dielectric relaxation spectroscopy (2D COS‐DRS) to study the molecular relaxation dynamics in ion‐irradiated poly(ether ether ketone) (PEEK). With the help of the high resolution and high sensitivity of 2D COS‐DRS, it was possible to locate the position of the motion of water molecules in the dielectric spectrum of PEEK. This occurred at −20°C and increased in intensity on increasing water contents. On irradiation, a new relaxation was observed at −75°C and −85°C for proton and helium ion‐irradiated samples, respectively. This increased in intensity on increasing radiation dose and was assigned to main‐chain phenyl motions of the cross‐linked units of the polymer. 2D COS‐DRS was also successfully applied to resolve the overlap in molecular events in the region of glass transition. Three processes that change in different directions with respect to ion irradiation dose were identified. These were at 160°C, 175°C, and 240°C and were assigned to the α relaxation, second α relaxation, and the onset of conductivity, respectively. In addition, hybrid 2D COS‐DRS was used to investigate the effect of the so‐called linear energy transfer effect, and the results showed that helium ions were more effective in cross‐linking PEEK. Copyright © 2013 John Wiley & Sons, Ltd.     

Surface Plasticization of Poly(ether ether ketone)

This paper describes a study of the surface plasticization and antiplasticization of an amorphous and a semicrystalline poly(ether ether ketone) (PEEK) in solvent environments using nanohardness method. A range of solvents (octane, chloroform, tetrachloroethane, acetone, dichlorobenzene, polyethyleneglycol (PEG), methanol and water) based on the Hilderbrand’s Solubility Parameter were selected as solvent environments. The results of the nanoindentation hardness experiments performed on the virgin and the solvent immersed polymeric surfaces are reported. The surface plasticization or antiplasticization is reported on the basis of the softening or the hardening of the near surface layers (?1 μm) after immersion of the polymeric surfaces in the solvent environments. Surface plasticization of the amorphous PEEK has been observed in organic solvents. The chlorine containing solvents have severely degraded the hardness of the amorphous polymer. A surface hardening of the amorphous PEEK has been observed after immersion in water. Semicrystalline PEEK was seen to exhibit a considerable inert behaviour to common organic solvents but chlorinated organic solvents and water have caused a decrease in the surface mechanical properties.     

聚醚醚酮分子结构对流动性和热性能的影响

本文用稍过量４、４’－二氯苯酮合成的聚醚醚酮（ＰＥＥＫ）样品，利用ＵＶ、ＭＩ、ＤＳＣ和ＴＧＡ等研究本氧阴离子及其相对浓度在树脂合成和加工过程中对ＰＥＥＫ分子结构和性能的影响．结果表明：苯氧阴离子端基引起支化交联反应，且随着其相对浓度增加而增加．采用过量４、４’－二氯苯酮合成ＰＥＥＫ，不仅能控制产物的分子量，而且有利于抑制支化交联反应，提高ＰＥＥＫ的流动性和热稳定性．本文还初步探讨了ＰＥＥＫ支化反应机理和支化高分子热分解机理．     

PEEK链分子内γ-松弛过程构象机理的研究

使用AM1半经验量化计算,研究在PEEK链分子内γ-松弛的构象机理。指出部分链段作曲柄式运动时,各相连苯环不断调节其相对位置。γ-松弛的活化能与苯环间相对转动势垒、链骨架绕骨架平面作曲柄式运动势垒及链间相互作用有关,本文估算各部分的大小,并对苯环在PEEK链内相对取向作进一步的计算,得到十分接近实验数据的结果。