High-performance conductive materials based on the selective location of carbon black in poly(ether ether ketone)/polyimide matrix

A novel high performance conductive material with excellent comprehensive properties was prepared by melt-blending, and its performances were adjusted by controlling the selective location of carbon black (CB) in poly(ether ether ketone) (PEEK)/thermoplastic polyimide (TPI) matrix. With increasing the CB loadings, the morphology of PEEK/TPI blends changed from sea-island to co-continuous structure, which was owing to the selective location of CB in TPI phase. Notably, with the selective location of CB in the induced co-continuous PEEK/TPI matrix, the electrical percolation threshold was reduced to 5 wt%, which was significantly lower than that of binary PEEK/CB (9 wt%) and TPI/CB (10 wt%) composites. And the electrical conductivity of ternary PEEK/TPI/CB composites was 10⁴ to 10⁶ times higher than that of binary composites at identical 7.5 wt% CB loading, which was attributed to the double percolation effect. Moreover, the incorporation of CB could improve the thermal and mechanical properties effectively.     

Design and preparation of graphene/poly(ether ether ketone) composites with excellent electrical conductivity

Graphene/poly(ether ether ketone) (m-TRG/PEEK) composites with excellent electrical conductivity were fabricated by hot pressing technique with thermally reduced graphene nanosheets (m-TRG) which were modified by poly(ether sulfone). Moreover, the conductive, thermal, and mechanical properties of PEEK/m-TRG composites were investigated by the precision impedance analyzer, thermal gravimetric analyzer, differential scanning calorimetry, and universal tester, respectively. The electrical conductivity of m-TRG/PEEK composites was greatly improved by incorporating graphene, resulting in a sharp transition from electrical insulator to semiconductor with a low percolation threshold of 0.76 vol.%. A high electrical conductivity of 0.18 S m^?1 was achieved with 3.84 vol.% of m-TRG. The data were compared with those of composites reduced chemically, and the results showed that thermal reduction was an effective method to acquire higher electrical conductive composites. The excellent electrical property should be attributed to the large specific surface area of m-TRG, well dispersion of m-TRG in PEEK matrix, and good compatibility of m-TRG with PEEK matrix, as proven by scanning electron microscope. Besides, m-TRG/PEEK composites also exhibited relatively good thermal and mechanical properties.     

碳纤维-AlN/聚醚醚酮复合材料的制备与性能

以聚醚醚酮(PEEK)为基体树脂、碳纤维(CF)和氮化铝(AlN)为填料,通过模压成型的方法制备了抗静电耐热型CF-AlN/PEEK复合材料。采用高阻计、导热系数测定仪、热失重、差示扫描量热仪和SEM研究了CF-AlN/PEEK复合材料的抗静电性能、热性能、力学性能以及降温速率对复合材料性能的影响,并探讨了后期热处理对力学性能的影响。结果表明:当CF和AlN的质量分数均为10%时,CF-AlN/PEEK复合材料的性能较优,其表面电阻率达到108 Ω,比PEEK的表面电阻率提高了6个数量级;导热系数为0.418 W·(m·K)-1,初始分解温度高达573℃;拉伸强度提高了40.4%;降温速率越低,复合材料的熔点越高;后期热处理会影响CF-AlN/PEEK复合材料的力学性能,在270℃下热处理2 h,其拉伸强度可达146 MPa,表明在生产过程中,加工温度是影响复合材料性能的因素之一。      

The effects of solvent sorption on the properties of poly(ether ether ketone)

A study has been carried out on the sorption of ortho-dichlorobenzene, N,N-dimethylformamide and water by poly(ether ether ketone) (PEEK). Two types of PEEK samples have been analysed; the first in the amorphous state and the second with a high crystallinity level. The sorption and desorption curves have been determined and the effect of the solvent presence on the mechanical properties has been analysed by means of the tensile test. PEEK is affected to a different extent by the solvents studied and also by the crystallinity of the polymer. Sorption takes place only in the case of amorphous PEEK. Its effect on the mechanical properties of PEEK is explained on the basis of the two concomitant processes that are the consequence of sorption, these are: plasticization and induced crystallization.     

Thin film and bulk deformation behaviour of poly(ether ether ketone)/poly(ether imide) blends

The deformation behaviour of amorphous thin films of poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI) blends was investigated over a wide temperature range by optical and transmission electron microscopy. All the materials showed localized shear deformation at temperatures well below Tg. In pure PEI and in blends with up to 60 wt% PEEK content, a transition from shear deformation to disentanglement crazing occurred as the temperature was raised. However, this transition was absent in PEEK, which deformed by shear over the whole temperature range, and similar behaviour was found for PEI/80 wt% PEEK. It is argued that at high PEEK content disentanglement crazing is suppressed by strain-induced crystallization and some evidence for crystalline order in deformed regions of initially amorphous PEEK thin films was obtained by electron diffraction. The thin film deformation behaviour of the blends was also shown to be consistent with their bulk deformation behaviour, a high temperature ductile–brittle transition being observed at low PEEK content in tensile tests. This revised version was published online in November 2006 with corrections to the Cover Date.     

Effect of carbon nanotubes on the mechanical properties and crystallization behavior of poly(ether ether ketone)

Pristine carbon nanotubes (CNTs) and noncovalently functionalized carbon nanotubes (f-CNTs) were used to prepare poly(ether ether ketone) (PEEK) composites (CNTs/PEEK and f-CNTs/PEEK) via melt blending. Noncovalently functionalized multiwalled nanotubes were synthesized using hydrogen-bonding interactions between sulfonic groups of sulfonated poly(ether ether ketone) (SPEEK) and carboxylic groups of nanotubes treated by acid (CNTs–COOH). The effects of these two kinds of nanotubes on the mechanical properties and crystallization behavior of PEEK were investigated. CNTs improved mechanical properties and promoted the crystallization rate of PEEK as a result of heterogeneous nucleation. Better enhancement of mechanical properties appeared in the f-CNTs/PEEK composites, which is ascribed to the good interaction between f-CNTs and PEEK. However, the strong interaction of f-CNTs and PEEK chains decreased the crystallization rate of PEEK for high content of f-CNTs.     

Molecular interaction and properties of poly(ether ether ketone)/liquid crystalline polymer blends incorporated with functionalized carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were functionalized with a carboxyl group (-COOH) to achieve better interfacial adhesions with both phases of the poly(ether ether ketone) (PEEK) and liquid crystalline polymer (LCP) in their blend. These strong interfacial interactions among the functionalized MWCNTs, PEEK and LCP improved the mechanical properties of the polymer blend. Three different weight percentages (0.6%, 1.2% and 1.8%) of acid modified CNTs were used with PEEK-LCP blend, for the preparation of nanocomposites. In PEEK-LCP blend, the ratio of PEEK and LCP was maintained as 10:6 respectively. The tensile strength and modulus of the composites were improved by 51% and 73% respectively with the incorporation of only 1.2% of MWCNT-COOH as compared to the unfilled PEEK/LCP blend. Moreover, careful studies of the molecular interaction, morphological, dynamic mechanical and thermal properties confirmed that a better miscibility between PEEK and LCP had been constituted in the presence of MWCNT-COOH. Therefore, it was found that the functionalized MWCNTs not only played the traditional role as reinforcing filler, but also performed a novel role as a compatibilizer for the PEEK/LCP blends.     

聚醚醚酮和烯丙基化合物改性双马来酰亚胺复合材料微观结构及力学性能

采用浓H₂SO₄氧化聚醚醚酮（PEEK）得到磺化聚醚醚酮（SPEEK）,以3,3'-二烯丙基双酚A （BBA）、双酚A双烯丙基醚（BBE）为活性稀释剂、SPEEK为改性剂、双马来酰亚胺（BMI）树脂为基体,浇注成型制备SPEEK/BBA-BBE-BMI复合材料,同时研究了SPEEK的改性效果及复合材料微观形貌与力学性能。结果表明：SPEEK改性效果较好,在FTIR中存在明显的磺酸基团特征峰,SEM和能谱分析表明,SPEEK微观形貌变化明显,硫元素含量较高;SPEEK/BBA-BBE-BMI复合材料的微观形貌显示,SPEEK在基体中呈现直径为2 μm左右的多孔状两相结构,且分散均匀,此多孔结构改善了复合材料的断裂形貌,由脆性断裂转变为韧性断裂,当断裂纹遇到SPEEK组分时受阻而出现不规则发散,此变化会赋予复合材料更加优异的性能。力学性能测试结果显示,当SPEEK含量为5wt%时,SPEEK/BBA-BBE-BMI复合材料的弯曲强度和冲击强度达到最佳,分别为147.93 MPa和15.74 kJ/mm²,分别比基体提高了49.47%和66.21%。     

聚醚醚酮增韧改性环氧树脂

采用共混法用聚醚醚酮(PEEK)改性环氧树脂(EP),借助差示扫描量热分析(DSC)确定了环氧树脂的固化工艺,测试了共混体系的工艺性能,研究了聚醚醚酮含量对环氧树脂力学性能的影响.借助扫描电子显微镜(SEM)对材料断裂面的形态结构进行了分析,探讨了体系的形态结构与冲击性能之间的关系.结果表明,在改性材料的韧性有所提高的同时,压缩强度、马丁耐热都没有降低.从断裂面的形态来看,是属于韧性断裂.当PEEK的加入量为6%时,韧性最好,达到19.1 kJ/m2,比纯的环氧树脂增加了107.6%.     

聚醚醚酮增韧改性环氧树脂

采用共混法用聚醚醚酮(PEEK)改性环氧树脂(EP),借助差示扫描量热分析(DSC)确定了环氧树脂的固化工艺,测试了共混体系的工艺性能,研究了聚醚醚酮含量对环氧树脂力学性能的影响。借助扫描电子显微镜(SEM)对材料断裂面的形态结构进行了分析,探讨了体系的形态结构与冲击性能之间的关系。结果表明,在改性材料的韧性有所提高的同时,压缩强度、马丁耐热都没有降低。从断裂面的形态来看,是属于韧性断裂。当PEEK的加入量为6%时,韧性最好,达到19．1kJ/m~2,比纯的环氧树脂增加了107．6%。     

Fabrication of multilayer dielectrically loaded antennas using aqueous electrophorectic deposition of polyether ether ketone

The paper presents proof of concept of a viable multilayer technology to enhance the performance of multifilar helix, receive-only satellite antennas. Approximately, 30-μm layers of polyether ether ketone (PEEK) were deposited onto the Cu filars of a single layer dielectrically loaded multifilar helix antenna using aqueous electrophoretic deposition (EPD). The PEEK coating was densified at ~400–420 °C in flowing N₂ to prevent oxidation of the Cu filars. A second Cu metallisation was deposited onto the surface of the PEEK and the resulting antenna characterised. The multilayer antenna revealed a dual band response with peak radiation efficiencies >25 % and ~50 % increase in bandwidth. Multilayered surface architectures fabricated from PEEK using EPD, therefore, show great potential for the development of a broad range of high-performance multiband dielectrically loaded antennas whose peak frequencies may, in principle, be tuned by modifying the thickness of the PEEK layer.     

热致液晶聚酯/聚醚醚酮复合纤维的制备与表征

将热致液晶聚酯(VA)与聚醚醚酮(PEEK)共混后,通过熔融纺丝制备了热致液晶聚酯/聚醚醚酮复合纤维,并对复合纤维的热性能、聚集态结构、相态结构和力学性能进行了研究。结果表明,VA的加入能够降低PEEK纤维的玻璃化温度和冷结晶温度,同时PEEK的结晶温度也随着VA的加入而升高;VA的加入有利于提高PEEK的结晶性能,使得PEEK晶粒尺寸变大,晶面间距变小,晶体更加完善,晶区取向增强;随着VA添加量的增大,VA相逐渐由球状或椭球状向微纤状变化;随着喷丝头拉伸比的增大,VA相的长径比呈现先增大后减小的趋势;添加1%和2%的VA后,复合纤维的断裂强度有少许下降,而当VA的添加量增大到4%后,复合纤维的总拉伸倍数提高,并且断裂强度有一定的提升。     

聚醚醚酮改性研究进展

聚醚醚酮(PEEK)作为一种新型高性能热塑性工程塑料,在许多工程领域有着广泛的应用.采用不同手段增强PEEK,改善其加工性能和力学性能、热性能、摩擦学性能,有利于降低材料成本和进一步拓展应用范围.本文从纤维增强PEEK、颗粒填充PEEK、PEEK表面改性、与聚合物共混等方面综述了PEEK改性研究的进展情况.     

Evaluating the orientation and dispersion of carbon nanotubes inside nanocomposites by a focused-ion-beam technique

Poly ether ether ketone (PEEK)/multi-walled carbon nanotubes (MWNTs) nanocomposites were fabricated to characterize and understand the orientation and dispersion of carbon nanotubes (CNTs) in a polymer matrix. A focused-ion-beam (FIB) technique was used for milling the nanocomposite by a focused gallium ion beam, and the MWNTs were carefully observed. The PEEK preferentially disappeared when the Ga⁺ ion beam milled the composite, and MWNTs were exposed on the surface of composites. Using this method, it is very easy to estimate and directly evaluate the orientation of the MWNTs in the polymer matrix even though they are embedded in the polymer matrix. Transmission electron microscopy (TEM) was employed to characterize the detailed position of the nanotubes in the PEEK matrix.     

An investigation of the microstructure of a cryogenically mechanically alloyed polycarbonate-poly(aryl ether ether ketone) system

This work investigates processing-microstructure relationships of a model cryogenically mechanically alloyed polymer-polymer system consisting of polycarbonate (PC) and poly(aryl ether ether ketone) (PEEK). Powders mechanically alloyed for 10 hours were imaged via transmission electron microscopy (TEM) and were shown to have a two-phase microstructure physically mixed on a sub-micron level. These powders were processed into coupons using a laboratory scale ram-injection molder, and the resulting microstructure of the coupons was investigated as a function of mechanical alloying and injection molding parameters. Atomic force microscopy, TEM, and scanning transmission X-ray microscopy all revealed that the intimate blending achieved during the mechanical alloying process was not retained upon post-processing using this conventional polymer processing technique.     

The environmental fatigue behaviour of carbon fibre reinforced polyether ether ketone

The fatigue behaviour of carbon fibre/PEEK composite is compared with that of carbon/ epoxy material of similar construction, particularly in respect of the effect of hygrothermal conditioning treatments. Laminates of both materials were of 0/90 lay-up, and they were tested in repeated tension at 0° and at 45° to the major fibre axis. The superior toughness of the polyether ether ketone and its better adhesion to the carbon fibres results in composites of substantially greater toughness than that of the carbon/epoxy material, and this is reflected in the fatigue behaviour of the carbon fibre/PEEK. The tougher PEEK matrix inhibits the development of local fibre damage and fatigue crack growth, permitting a 0/90 composite with compliant XAS fibres to perform as well in fatigue as an epoxy laminate with stiffer HTS fibres. Hygrothermal treatments have no effect on the fatigue response of either material in the 0/90 orientation. The fatigue response of a cross-plied carbon/PEEK laminate in the ±45° orientation is much better than that of equivalent carbon/epoxy composites, again because the superior properties of the thermoplastic matrix.     

The mechanical properties of insert-molded poly (ether imide) (PEI)/C fiber poly (ether ether ketone)(PEEK) composites

The mechanical properties of insert-molded poly(ether imide) (PEI)/carbon fiber poly(etheretherketone) (CF PEEK) have been examined. Bimaterial composite specimens were constructed by injecting CF PEEK into a mold containing one-half of a PEI tensile specimen. These PEI/CF PEEK composites retained much of their strength and dimensional integrity at temperatures as high as 200°C. Variations in test speed had little affect on breaking strains or stiffness. For two grades of PEI examined, properties were independent of the molecular weight of the PEI. Ultimate properties and fracture surfaces suggested good adhesion between the PEI and CF PEEK, possibly aided by miscibility between the two materials. The PEI/CF PEEK bimaterial composites behaved similarly to PC/CF PEEK specimens, but exhibited higher breaking stresses and moduli, both at room and elevated temperatures.     

剪切载荷下温度和应变率对碳纤维增强聚醚醚酮复合材料强化行为的影响

碳纤维增强聚醚醚酮(CF/PEEK)是一种高性能热塑性复合材料,在航空航天领域有着广阔的应用前景。由于PEEK具有温度和应变率相关的非线性行为,导致CF/PEEK复合材料在基体主导的面内剪切方向也有类似的力学行为。本文在不同的温度和应变率下对CF/PEEK复合材料试件进行了剪切实验,将应力-应变曲线分为线性与非线性部分,发现温度和应变率对CF/PEEK复合材料的屈服应力有着较大的影响。随着温度从20℃升高到130℃屈服应力下降了66%左右,下降速度先快后慢,随着应变率从10?5 s?1提高到0.1 s?1屈服应力均匀增大了35%左右。将所得规律拟合背应力经验公式,修改了经典的热塑性复合材料本构模型的屈服函数。并编写VUMAT用户子程序对CF/PEEK复合材料剪切实验进行数值分析,与实验结果对比发现非线性阶段的剪切应力-应变关系及屈服点的剪切应力吻合良好,但是由于纤维和PEEK基体的浸润性较差,导致CF/PEEK复合材料内部存在孔隙缺陷,影响了CF/PEEK复合材料的初始剪切弹性行为,导致加载初始阶段存在偏差。      

Preparation and characterization of poly(ether ether ketone)/poly(ether imide) [PEEK/PEI] blends for fused filament fabrication

Journal of Materials Science - The present study focuses on the preparation and characterization of a poly(ether ether ketone)/poly(ether imide) [PEEK/PEI] blend for application in additive...     

Carbon-nanofibre-reinforced poly(ether ether ketone) fibres

Nano-reinforced fibres were spun from a semicrystalline high-performance poly(ether ether ketone) containing up to 10 wt% vapour-grown carbon nanofibres using conventional polymer processing equipment. Mechanical tensile testing revealed increases in nanocomposite stiffness, yield stress, and fracture strength for both as-spun and heat-treated fibres. X-ray and differential scanning calorimetry analyses were performed in order to investigate both the orientation of nanofibres within the polymer matrix and the matrix morphology. The carbon nanofibres were found to be well aligned with the direction of flow during processing. Significantly, the degree of crystallinity of the poly(ether ether ketone) matrix was found to increase with the initial addition of nanofibres although the crystal structure was not affected. The measured increase in composite tensile modulus is compared to injection-moulded nanocomposite samples made from the same blends. The results highlight the need to characterise the matrix morphology when evaluating nanocomposite performance and hence deducing the intrinsic properties of the nanoscale reinforcement.