Influence of carbon nanotubes on the thermal, electrical and mechanical properties of poly(ether ether ketone)/glass fiber laminates

Novel poly(ether ether ketone) (PEEK)/single-walled carbon nanotube (SWCNT)/glass fiber laminates incorporating polysulfone as a compatibilizing agent were fabricated by melt-blending and hot-press processing. Their morphology, mechanical, thermal and electrical properties were investigated and compared with the behavior of similar non-compatibilized composites. Scanning electron micrographs demonstrated better SWCNT dispersion for samples with polysulfone. Thermogravimetric analysis indicated a remarkable improvement in the thermal stability of PEEK/glass fiber by the incorporation of SWCNTs wrapped in the compatibilizer, ascribed to a significant thermal conductivity enhancement. Differential scanning calorimetry showed a decrease in the crystallization temperature and crystallinity of the polymer with the addition of both wrapped and non-wrapped SWCNTs. The laminates exhibit anisotropic electrical behavior; their conductivity out-of-plane is lower than that in-plane. Dynamic mechanical studies revealed an increase in the storage modulus and glass transition temperature in the presence of polysulfone. Mechanical tests demonstrated significant enhancements in stiffness, strength and toughness by the incorporation of wrapped nanofillers, whilst the mechanical properties of non-compatibilized composites only improved marginally. Samples with laser-grown SWCNTs exhibit enhanced overall performance. This investigation confirms that SWCNT-reinforced PEEK/glass fiber compatibilized composites possess excellent potential to be used as multifunctional engineering materials in industrial applications.     

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.     

Thermal,mechanical, and dielectric properties of aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) layered composites

In this study, a novel aluminum phosphate (AlPO₄) heat‐resistant layer reinforced with aluminum silicate fiber (ASF) was successfully compounded on a poly(ether sulfone) (PES) matrix via the preparation process of high‐temperature heat treatment and vacuum hot‐pressing sintering technique. The influence of the ASF content on the morphology, thermal, mechanical, and dielectric properties of the as‐fabricated aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) (ASF/AlPO₄–PES) layered composite was investigated. The results reveal that the incorporation of aluminum silicate fiber/aluminum phosphate (ASF/AlPO₄) heat‐resistant layer can significantly improve the thermal stability and mechanical performances of the PES matrix composites. Compared with the pristine PES, the ASF/AlPO₄–PES layered composite containing 8.0 wt % ASF exhibited better high‐temperature resistance properties (300 °C) and a lower thermal conductivity (0.16 W m^?1 K^?1). Furthermore, the dielectric constant and dielectric loss tangent of this PES matrix composite decreased to 2.16 and 0.007, respectively. Meanwhile, the frequency stability of the dielectric properties for the ASF/AlPO₄–PES layered composites was remarkably enhanced with increasing ASF addition at frequencies ranging from 10² Hz to 5 MHz. This was attributed to the existence of microscopic pores within the ASF/AlPO₄ layer and the strong interfacial bonding between the ASF/AlPO₄ layer and the PES matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45542.     

Study on poly(ether ether ketone)/organically modified montmorillonite composites

Abstract

Novel poly(ether ether ketone) (PEEK)/organically modified montmorillonite (OMMT) composites containing 0–10 wt-% fractions of OMMT were prepared by melting blending method and the microstructure, thermal and mechanical properties were investigated using different characterisation techniques. X-ray diffraction and transmission electron microscopy showed that the OMMT was well dispersed with microscale in the PEEK matrix. Differential scanning calorimetry indicated that the glass transition temperature T _g and melt temperature T _m of PEEK/OMMT composites (POMCs) were hardly affected by the addition of OMMT, while the crystal temperature T _c decreased when the amount of OMMT excessed 1 wt-%. The data of thermogravimetric analysis exhibited that the thermal stability of POMCs in higher temperature region was better than that of pure PEEK. The results of mechanical properties test revealed that modulus and strength of POMCs increased with the content of OMMT, whereas the elongation at break and impact strength of POMCs decreased.     

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     

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。     

Effect of the addition of silane coupling agents on the properties of wollastonite‐reinforced poly(ether ether ketone) composites

The wollastonite was grafted with different silane coupling agents, which could improve interface adhesion. Wollastonite and modified wollastonite‐reinforced poly(ether ether ketone) (PEEK) composites were prepared by melt blending. The mechanical properties, rheology behavior, and thermal properties of the composites were investigated. The modified wollastonite‐reinforced PEEK composites exhibited better mechanical properties than the unmodified wollastonite‐reinforced PEEK composites based on good interfacial adhesion. The composites had lower activation volume and complex shear viscosity. Furthermore, the modified wollastonite‐reinforced PEEK composites had higher crystallization peak temperature (T_c) and crystalline fraction (χ_c) compared with the unmodified wollastonite‐reinforced PEEK composites. This study shows that the traditional silane coupling agents could effectively improve the performance of PEEK composites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Studies on the mechanical,thermal, and morphological properties of poly(ether ether ketone)/poly(ether sulfone)/barium titanate nanocomposites: Correlation of experimental results with theoretical predictive models

In this study, mechanical, thermal, and morphological properties of the nanocomposites fabricated with the optimized blend of poly(ether ether ketone) (PEEK) and poly(ether sulfone) (PES) incorporated with nanobarium titanate (BT) were investigated. The optimized blend was based on the mechanical and thermal properties of the PEEK and PES in the ratio of 75 : 25 wt %. Nanoparticles were incorporated into the optimized blend with the help of twin‐screw extruder. The concentration of nano‐BT was varied from 2 to 6 wt % (0.41–1.28 vol %). With the increase in the nanosized BT concentrations, the tensile strength, tensile modulus, and elongation at break increased, whereas the crystallinity of the nanocomposites calculated by using differential scanning calorimetry method was found to decrease marginally. Morphological studies were carried out using scanning electron microscopy. The nanocomposites were evaluated by using theoretical predictive models according to “Pukanszky model” applicable to tensile strength and “Takayanagi's model” and “Guth and Smallwood model” applicable to tensile modulus. Upper and lower boundary of Hashin–Shtrikman model as well as Paul's model, applicable to tensile modulus, were also used to compare the experimental data. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of SiO2 nanoparticles-decorated SCF on mechanical and tribological properties of cenosphere/SCF/PEEK composites

A silicon oxide (SiO₂) nanoparticles-decorated short carbon fiber (SCF) hybrid (SCF-SiO₂) was designed to improve the weak interfacial bonding between fibers and matrix. Nano-SiO₂ was grafted onto carbon fibers by introducing amino group and epoxy group on the surface of carbon fibers and SiO₂, respectively. The chemical composition of SCF-SiO₂ was analyzed by Fourier transform infrared spectrometer and energy-dispersive spectrometry, the microstructure of SCF-SiO₂ were investigated by scanning electron microscope, and then the hybrid filler was introduced into Poly(ether ether ketone) (PEEK). Due to the strong interfacial interaction between filler and matrix, the mechanical and tribological properties of SCF-SiO₂/PEEK composites were significantly better than SCF/PEEK composites. In order to further improve the tribological properties of the composites, micrometer-sized cenosphere (CS) particles were introduced into the aforementioned system to prepare multicomponent composites. The test results of friction and wear indicate that the CS/SCF-SiO₂/PEEK composites have the optimal tribological properties. Compared with pure PEEK, the friction coefficient of CS/SCF-SiO₂/PEEK composites under 200 N load decreases by 56.4% and the specific wear rate decreases by 87.4%. Meanwhile, the thermal decomposition temperature of CS/SCF-SiO₂/PEEK composites is increased by 40 °C compared to pure PEEK. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48749.     

Functionalization of multi‐walled carbon nanotubes and their effect on the tribological properties of poly(ether ether ketone) composites

A series of copolymers containing conjugated fluorene groups as a compatibilizer to improve the dispersion of multi‐walled carbon nanotubes (MWCNTs) were prepared and used to improve the wear resistance of poly(ether ether ketone)/graphite (PEEK/GP) composites. The solubility of MWCNTs had a maximum at a concentration ratio of 2:1 polymer:MWCNTs. Transmission electron microscopy indicated that polymer ? MWCNT interactions were capable of partially debundling the nanotubes in chloroform, with individual nanotubes or small bundles clearly observed. The tribological properties of PEEK composites incorporating the modified MWCNTs were investigated using a pin‐on‐disc apparatus and a block‐on‐ring apparatus. The PEEK composites had a lower frictional coefficient under the block‐on‐ring testing condition, but a lower wear rate was achieved in the pin‐on‐disc test. © 2017 Society of Chemical Industry     

Mechanical,electrical, and thermal properties of graphene nanosheet/aluminum nitride composites

Graphene nanosheet (GNS)/aluminum nitride (AlN) composites were prepared by hot-pressing and effects of GNSs on their microstructural, mechanical, thermal, and electrical properties were investigated. At 1.49 vol% GNSs content, the fracture toughness (5.09 MPa m^1/2) and flexural strength (441 MPa) of the composite were significantly increased by 30.17% and 17.28%, respectively, compared to monolithic AlN. The electrical conductivity of the composites was effectively enhanced with the addition of GNSs, and showed a typical percolation behavior with a low percolation threshold of 2.50±0.4 vol%. The thermal conductivity of the composites decreased with the addition of GNSs.     

Enhanced mechanical and electrical properties of carbon fiber/poly(ether ether ketone) laminates via inserting carbon nanotubes interleaves

The carbon fiber/(carbon nanotubes/polyetherimide)/poly ether ether ketone (CF/(CNTs/PEI)/PEEK) laminates are prepared by inserting carbon nanotubes/polyetherimide (CNTs/PEI) interleaves into interlaminar region. The mechanical properties and electrical conductivities of the developed laminates are evaluated. The results indicate that the interlaminar shear strength and flexural strength of CF/(CNTs/PEI)/PEEK laminates are increased by 42.9% and 24.7%, after inserting CNTs2.91/PEI interleaves, respectively. The cross-sectional images of laminates after mechanical tests verify strong fiber-resin adhesion by scanning electron microscope observation. The pertinent mechanism responsible for the improvement of mechanical properties is mechanical interlocking effect of CNTs. After incorporating CNTs/PEI interleaves, the electrical conductivity of laminates is markedly improved due to the formation of conductive pathway. This work suggests that this method is compatible with the preparation process of thermoplastic composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48658.     

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.     

Tin-Lead flake poly (ether sulfone) composite formed by in-situ melt processing of tin-lead particles

Tin-lead (60Sn-40Pb) flake poly(ether sulfone) (PES) composites in which the flakes were partially interconnected and of average thickness 2 μm were prepared by hot pressing molten Sn-Pb particles in a matrix of PES at a temperature above the melting temperature of Sn-Pb and above the glass transition temperature of PES. Hot pressing at 240°C and 6.51 Mpa resulted in a 15 vol% Sn-Pb composite of lower electrical resistivity and higher electromagnetic interference shielding effectiveness than a PES composite containing 15 vol% aluminum flakes that were not formed in-situ. The electrical properties of the in-situ PES/Sn-Pb flake composites were much better than those of PES/Sn-Pb flake composites were fabricated by hot pressing at 310°C (the manufacturer-suggested fabrication temperature), though the mechanical properties were not as good.     

Preparation of organically dispersible graphene nanosheet powders through a lyophilization method and their poly(lactic acid) composites

Solvent-free graphene nanosheets (GNSs), which are in the form of chemically reduced graphite oxide nanosheets, were prepared using an environmentally friendly freeze drying process. Compared with those produced through the vacuum filtration method, the lyophilized GNS powders were extremely light, loosely packed and could be readily redispersed in appropriate organic media like N,N-dimethylformamide as individual sheets with the aid of sonication. The ability of the as-lyophilized GNS powders to be redispersed in organic solvents facilitates their incorporation into polymers like poly(lactic acid) through a solution-based processing method. In the resulting composite, GNSs were uniformly dispersed in the matrix and enhanced the mechanical and thermal properties of the host polymer, suggesting the great potential of the lyophilized GNS powders in the field of polymer composites.     

Thermal,electrical, and mechanical properties of polyethylene–graphene nanocomposites obtained by in situ polymerization

In this study, we investigated the thermal, dynamic mechanical, mechanical, and electrical properties of polyethylene (PE)–graphene nanosheet (GNS) nanocomposites, with GNS amounts from 0 to 20 wt %, prepared by in situ polymerization. The thermal stability was evaluated by thermogravimetric analysis (TGA) and showed that the addition of GNSs to the polyolefin matrix increased the onset degradation temperature by 30°C. The electrical conductivity, measured by the impedance technique, presented a critical percolation threshold of 3.8 vol % (8.4 wt %) of GNS. A slight decrease in the tensile strength was found. On the other hand, dynamic mechanical analysis showed an increase in the storage modulus of the nanocomposites compared with that of neat PE. The glass‐transition temperature value increased from ?111°C (neat PE) to ?106°C (PE/6.6 wt % GNS). All of these results show that PE became stiffer and thermally more stable and could be transformed from an insulator to a semiconductor material in the presence of GNSs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

PEEK/diatomite composites by in situ polymerization: Synthesis,characterization and fundamental properties

In this study, poly (ether ether ketone)/diatomite composites (PEEK/diatomite composites) were prepared by in situ polymerization. In contrast to the direct melt-compounding method, particles are produced with up to 25 wt % higher filler content by the in situ polymerization method. We found that filling with diatomite improved the mechanical properties of PEEK by about 15%. Scanning electron microscopy revealed that the diatomite particles are uniformly dispersed in the PEEK matrix. Furthermore, the PEEK resin penetrates into the diatomite channels to form interpenetrating organic–inorganic network structures. The thermal stabilities of the composites were studied by thermogravimetric analysis, which revealed that they possess excellent thermal stabilities; these PEEK/diatomite composites exhibit higher decomposition-onset temperatures than virgin PEEK and lower rates of decomposition. This is attributable to interactions between the diatomite and the matrix, with the diatomite acting as a physical barrier between the polymer and the superficial zone where polymer combustion takes place. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46983.     

High performance thermoplastic composites: Study on the mechanical,thermal, and electrical resistivity properties of carbon fiber‐reinforced polyetheretherketone and polyethersulphone

High temperature processing thermoplastic polymers, polyetheretherketone (PEEK) and polyethersulphone (PES), were melt blended with carbon fibers (CFs) to make composites. These composites were investigated for their mechanical, thermal, and electrical properties. Mechanical properties that are expressed in terms of storage modulus, loss, and damping were enhanced with the addition of CFs. Thermal properties were determined by DSC and TGA. These methods help to understand the effects of fiber content and fiber–matrix adhesion in the composites. Composites were also tested for their electrical and thermal conductivity because CFs leave the composites thermally and electrically conductive. CFs enhanced the crystallinity of the PEEK appreciably that in turn influenced thermal conductivity, electrical resistivity, and the stiffness of PEEK/CF (composites of PEEK with CFs). PES/CF (composites of PES with CF) shows a different behavior due to the amorphous nature of PES. The work involves one filler and two different matrices, and so it provides an interesting comparison of how matrix morphology can influence the properties of composites. POLYM. COMPOS. 28:785–796, 2007. © 2007 Society of Plastics Engineers.     

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     

Enhanced electrical properties by tuning the phase morphology of multiwalled carbon nanotube‐filled poly(ether ether ketone)/polyimide composites

A novel high‐performance material with enhanced electrical properties was obtained by tuning the phase morphology of poly(ether ether ketone) (PEEK)/thermoplastic polyimide (TPI)/multiwalled carbon nanotube (MWCNT) composites. MWCNTs were selectively located in the TPI phase due to discrepant affinity of MWCNTs between PEEK and TPI. The dependence of the electrical properties of the PEEK/TPI/MWCNT composites on the phase morphology was investigated by changing the PEEK/TPI ratio, and the maximum conductivity was achieved with a PEEK/TPI ratio of 50/50, which could be explained by the selective location of MWCNTs and the co‐continuous phase morphology of the composites. © 2015 Society of Chemical Industry