Polyetherimide Matrix Research Articles

Effect of expanded graphite and PEI-co-Silicon Rubber on the thermo mechanical, morphological as well as rheological properties of in situ composites based on poly (ether imide) and liquid crystalline polymer

Nanocomposites of polyether imide (PEI) and liquid crystalline polymer (LCP) with either MWCNT, Expanded Graphite (EG) or in combination of both EG and PEI-co-Silicon Rubber were prepared by melt blending process. The compatibility between the polymeric phases (PEI&LCP) was observed to be increased by the addition of PEI-co-Silicon Rubber while the only MWCNT added system (PLC) resulted in smaller LCP droplets. A continuous morphology was produced in presence of both PEI-co-Silicon Rubber and EG both added system (PLGR). This was due to the compatibilizing effect of PEI-co-Silicon Rubber. FTIR analysis revealed interaction between PEI and LCP in presence of PEI-co-Silicon Rubber. Remarkable increment of storage modulus was observed with the addition of EG and PEI-co-Silicon Rubber. Transmission Electron Microscope (TEM) analysis showed better dispersion of multiple graphene layers of EG in presence of PEI-co-Silicon Rubber compatibilized system. Tensile and Young’s modulus both were highest for EG/ PEI-co-Silicon Rubber added system. This is due to flexible compatibilizing effect of PEI-co-Silicon Rubber which delayed the detachment of LCP domain from the PEI matrix and thus detains the fracture.

The addition of functionalized graphene oxide to polyetherimide to improve its thermal conductivity and mechanical properties

The thermal and electrical conductivity and mechanical properties of polyetherimide (PEI) containing either alkyl-aminated (enGO) or phenyl-aminated graphene (pnGO) oxides were studied. A solution casting method was used to prepare functionalized graphene oxide/PEI composites with different filler contents. The introduction of functionalized graphene oxide to the PEI matrix improved the thermal conductivity, electrical conductivity, and mechanical properties. The thermal conductivities of the enGO 3 wt%/PEI and pnGO 3 wt%/PEI composites were 0.324 W/mK and 0.329 W/mK, respectively, due to the high thermal conductivity of the graphene-based materials and the strong interface adhesion due to the filler surface treatment between the fillers and the matrix. The electrical conductivities of the functionalized graphene oxide/PEI composites were larger than that of PEI, but the electrical conductivity values were generally low, which is consistent with the magnitude of the insulator. The strong interfacial adhesion between the fillers and the matrix led to improved mechanical properties. Copyright © 2014 John Wiley & Sons, Ltd.

Foaming behaviors of polyetherimide/ polypropylene-graft-maleic anhydride blends in the microcellular injection molding process

In this study, foaming behaviors of polyetherimide (PEI)/polypropylene-graft-maleic anhydride (PPMA) blends with different fractions of PPMA are investigated by the microcellular injection molding (Mucell) using N2 as the blowing gas. The results indicate that the addition of PPMA can obtain more the interface in blends than PP. Meanwhile, the microcellular PEI/PPMA foams achieve higher void fraction and cell density than that of PEI/PP and neat PEI matrix, and then the cell diameter also significantly decreases from 30 µm to less 10 µm. The excellent cell properties can be attributed to interfacial effect of binary blends. The binary interface decreases the nucleation energy barrier and forms sufficient paths which improve diffusibility of blowing gas, so the microcellular PEI/PPMA foams obtain more nucleating points and paths of supporting cell growth.

Thermal conductivity improvement of surface-enhanced polyetherimide (PEI) composites using polyimide-coated h-BN particles.

In this study, we investigated the thermal conductivities and mechanical properties of polyetherimide (PEI) composites using polyimide (PI)-coated h-BN (PI-BN) particles. We found that PI-coated h-BN effectively increased adhesion with the PEI matrix, imparting enhanced mechanical and thermal stability and thermal conductivity with increasing BN content. The thermal conductivity of the PEI composite containing 60 wt% PI-BN was 3.3 W m(-1) K(-1), while the thermal conductivity of the PEI/BN composite without modification was 2.6 W m(-1) K(-1). The PEI/PI-BN composites show higher impact strengths than the PEI/BN composites because of less BN particle agglomeration and good wettability between PEI and h-BN. The results indicate that the PI-coated BN incorporated into the PEI matrix effectively enhances the thermal conductivity and mechanical properties of the PEI composites.

Hybrid films of polyetherimide containingin situgrown Ag, Pd, and AgPd alloy nanoparticles: Synthesis route, morphology, and gas transport properties

In this study, bimetallic/polymer films are synthesized from polyetherimide (PEI), palladium acetate and silver nitrate for a wide range of total metal amount (from 0 to 30 wt %) and different Ag to Pd molar ratios. Hybrid precursor films are first prepared from polymer/metal complex solutions and the metal nanoparticles are then generated within the PEI matrix by annealing the precursor film under specific conditions. Reference neat PEI films and monometallic films are prepared in the same conditions. Interestingly, formation of AgPd alloys directly within the polymer films is for the first time obtained from a very simple and environmentally friendly route. Based on X-ray diffraction and transmission electron microscopy analyses, a nanostructuration mechanism is proposed. The interactions of hydrogen towards the nanocomposites are investigated and discussed as a function of the nanoparticle composition. The impact of the nanostructuration is also studied on H2, CO2, and He permeation properties. Significant improvement of barrier properties is achieved. The pertinent parameters of the gas transport are identified and modelled for each gas/composite system. Finally, from both morphological and gas transport analyses, it is concluded that in situ generation AgPd alloys with Pd to Ag ratio above 1 leads to very interesting and promising materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1211–1220

Graphting polyimide to MWCNT for enhancing dispersion and properties of MWCNT/polyetherimide nanocomposites

Polyetherimide-grafted multi-walled carbon nanotube (denoted as MWCNT-PEI), polyimide-grafted MWCNT (MWCNT-PI), and acid-treated MWCNT (MWCNT-A) were prepared and well characterized by Raman spectroscopy, thermo gravimetric analysis, x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. After mixing with polyetherimide (PEI), a series of MWCNT/PEI nanocomposite films with different weight percentages of MWCNT-A, MWCNT-PEI and MWCNT-PI were fabricated by solution casting. Both PEI/MWCNT-PEI and PEI/MWCNT-PI nanocomposite films performed better thermal stability, mechanical property and electric conductivity than PEI/MWCNT-A due to the improved dispersion and compatibility with the PEI matrix.

Compositing Polyetherimide with Polyfluorene Wrapped Carbon Nanotubes for Enhanced Interfacial Interaction and Conductivity

A novel approach to chemically functionalize multiwalled carbon nanotubes (MWCNTs) for making superior polyetherimide (PEI) nanocomposites with polyfluorene polymer is presented. In this approach, MWCNTs are non-covalently functionalized with poly(9,9-dioctyfluorenyl-2,7-diyl) (PFO) through π-π stacking as confirmed by UV-vis, fluorescence, and Raman spectra. Atomic force microscopy as well as scanning and transmission electron microscopy shows the PFO coated MWCNTs, which provides excellent dispersion of the latter in both solvent and PEI matrix. The strong interaction of PFO with PEI chains, as evidenced from fluorescence spectra, supports the good adhesion of dispersed MWCNTs to PEI leading to stronger interfacial interactions. As a result, the addition of as little as 0.25 wt % of modified MWCNTs to PEI matrix can strongly improve the mechanical properties of the composite (increase of 46% in storage modulus). Increasing the amount of MWCNTs to 2.0 wt % (0.5 wt % PFO loading) affords a great increase of 119% in storage modulus. Furthermore, a sharp decrease of 12 orders of magnitude in volume resistivity of PEI composite is obtained with only 0.5 wt % of PFO modified MWCNT.

Mixed matrix membranes incorporated with cubic-MOF-5 for improved polyetherimide gas separation membranes: Theory and experiment

Cubic metal-organic framework 5 (C-MOF-5) nanocrystals with a high surface area (2387m2/g) were successfully synthesized. The structure of C-MOF-5 nanocrystals was characterized by XRD, FTIR, particle size analysis, and N2 adsorption techniques. Novel mixed matrix membranes (MMMs) containing C-MOF-5 inside an polyetherimide (PEI) matrix were prepared using solution casting method and characterized by SEM, FTIR, and single gas permeation analyses. The SEM images of the MMM cross-sections revealed that C-MOF-5 particles have changed the morphology of polymer matrix. In addition, it has attained the proper distribution of filler as well as good compatibility between the filler and the polymer. The results showed that the C-MOF-5 nanocrystals facilitated the gas transport along the membranes and for all gases (H2, CO2, CH4, and N2), permeabilities, diffusivities, and solubilities of the MMMs were increased with increasing the loading of C-MOF-5 nanocrystals at ambient temperature and pressure of 6bar. Incorporation of 5wt.% of C-MOF-5 into pure PEI resulted in ∼40% increase in H2 permeability and the separation factor (αi,jP) of H2/CO2, H2/CH4, CO2/CH4, and CH4/N2 was changed from 5.99, 111.89, 18.67, 0.9 to 6.13, 117.42, 19.17, and 0.92, respectively. For high loadings of C-MOF-5s (15 and 25wt.%), the mentioned separation factors (αi,jP) were increased except for H2/CO2. CO2 and CH4 permeability was strongly affected by the solubility coefficient and less affected by the diffusion coefficient. On the other hand, N2 permeability was strongly affected by the diffusion coefficient and less affected by the solubility coefficient. The experimental gas permeations through C-MOF-5/PEI nanocomposite with different filler loadings were fitted well on Higuchi model.

Influence of fiber–matrix interface on abrasive wear performance of polymer composites

* Present address: MED, Shri G S Institute of Technology & Science, 23, Park Road, Indore, Madhya Pradesh 452003, India. Surface treatment of carbon fibers (CFs) is an excellent way to enhance the fiber–matrix adhesion. However, this is generally at a cost of deterioration in the strength of a fiber. The two effects in opposite directions control the net strength of a composite. The weightage of each factor depends on the selected method and dose. Authors have recently reported on three fiber-treatment techniques (using various doses) such as that with nano-YbF3 (new method); cold remote nitrogen–oxygen plasma (newer one) and γ rays apart from one traditional method of acid oxidation of a fiber. In the present paper, comparative aspects (benefits and limitations) of all these four methods are discussed to enable a right selection of a surface treatment technique of CF to design the composite with a right combination of strength and wear resistance in abrasive wear mode. The composites with these surface treated fabrics and polyetherimide matrix were developed and evaluated for various properties including abrasive wear performance. Specific wear rate of HNO3 treated composite was lowest among these composites while plasma treated composites showed least improvement. Scanning electron microscope (SEM) analysis of worn surfaces showed mechanisms responsible for improved performance of treated composites and high wear rate of untreated composites.

Synthesis of silver nanoparticles decorated MWCNTs and their application in antistatic polyetherimide matrix nanocomposite

A facile approach for fabricating antistatic polyetherimide (PEI) had been carried out by introducing poly(sodium acrylate) bonded multi-walled carbon nanotubes and silver nanoparticles (MWCNTs@PSA@Ag). The electrostatic discharge channel was well constructed through homogenously dispersed MWCNTs with polar PSA layer and enhanced by Ag nanoparticles. Chemical structures of MWCNTs@PSA@Ag were characterized by FTIR, XPS, Raman, TGA, UV–vis and TEM. Results revealed that PSA was covalently bonded onto the surface of MWCNTs. Thereby, the ester bond in PSA could improve the dispersion of MWCNT in PEI matrix, and assemble size controlled Ag nanoparticles through coordination bond. Thus, the percolation volume conductivity of MWCNTs@PSA@Ag/PEI nanocomposite was increased to 8.3×10−8S/cm at 0.75wt% concentration. Moreover, the percolation threshold was further declined to 0.5wt% concentration because ionic conduction of PSA could be formed after moisture absorption of MWCNTs@PSA@Ag/PEI nanocomposite in environment.

Polyetherimide/Bucky Gels Nanocomposites with Superior Conductivity and Thermal Stability

Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 10(4) Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable.

Cell morphology and mechanical properties of microcellular mucell® injection molded polyetherimide and polyetherimide/fillers composite foams

ABSTRACTMicrocellular polyetherimide (PEI) foams were prepared by microcellular injection molding using supercritical nitrogen (SC‐N2) as foaming agent. The effects of four different processing parameters including shot size, injection speed, SC‐N2 content, and mold temperature on cell morphology and material properties were studied. Meanwhile, multiwalled carbon nanotube (MWCNT), nano‐montmorillonoid (NMMT), and talcum powder (Talc) were introduced into PEI matrix as heterogeneous nucleation agents in order to further improve the cell morphology and mechanical properties of microcellular PEI foams. The results showed that the processing parameters had great influence on cell morphology. The lowest cell size can reach to 18.2 μm by optimizing the parameters of microcellular injection molding. Moreover, MWCNT can remarkably improve the cell morphology of microcellular PEI foams. It was worth mentioning that when the MWCNT content was 1 wt %, the microcellular PEI/MWCNT foams displayed optimum mechanical properties and the cell size decreased by 28.3% compared with microcellular PEI foams prepared by the same processing parameters. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4171–4181, 2013

Friction Riveting of glass–fibre-reinforced polyetherimide composite and titanium grade 2 hybrid joints

In this work, the feasibility of Friction Riveting on thermoplastic composite laminates with metals was investigated on glass–fibre-reinforced polyetherimide with titanium grade 2. Microscopy analysis (light optical and laser scanning confocal microscopy), temperature monitoring (infrared thermometry) and quasi-static mechanical testing (T-pull tensile testing) were used to investigate joint properties. Joints with reduced amounts of thermo-mechanically modified composite material with moderate to high tensile strengths (1.9–4.0kN) were achieved. The average process temperatures (430–464°C) of the molten matrix were below the range inducing the extensive thermal degradation of the polyetherimide matrix and out of the range inducing the plasticising of titanium grade 2. The Volumetric Ratio, a simplified analytical model describing the anchoring efficiency of the rivet, was demonstrated to be directly proportional to the tensile strength of the joint and therefore an adequate analytical model to describe the mechanical performance of joints. Finally, a correlation between the rotational speed, heat input, process temperature and rivet plasticising was observed. The higher the rotational speed was, the higher the heat input, temperature and deformation of the plasticised rivet tip became, leading to higher rivet anchoring performances.

Electrical, rheological and mechanical characterization of multiscale composite materials based on poly(etherimide)/short glass fibers/multiwalled carbon nanotubes

Composites based on poly(etherimide) matrix (PEI) with nanoscale reinforcements (multiwalled carbon nanotubes (MWCNTs)) and multiscale reinforcements (MWCNTs and Glass Fibers (GFs)) are processed by melt blending. For nanocomposite materials, we demonstrate that addition of MWCNTs (i) significantly improve electrical conductivity of PEI matrix, (ii) do not significantly improve the mechanical properties (young and flexural modulus) but strongly degrades the strain at break. In the case of multiscale composite materials PEI_GF_MWCNT, strain at break increases with the nanofiller content, and the electrical properties are the same than that in the case of nanocomposites. TEM observations are performed at the PEI/GF interfaces and clearly show a preferential location and orientation of MWCNTs along and perpendicularly to the GFs which explain the evolution of the strain at break for the multiscale composite materials.

Strengthening of a Fibre-Matrix Interface: A Novel Method Using Nanoparticles

The surface of carbon fabric (CF) was treated with nanoparticles (NPs) of Ytterbium fluoride (YbF3) (40–80nm size) in various amounts (0, 0.1, 0.3 and 0.5wt%) to improve its wettability with a Polyetherimide (PEI) matrix. The effect of treatment on the fibres of the CF was also studied by adhesion testing and fibre tow tension testing. An improvement in wettability with PEI and a slight reduction in the tensile strength of the CF was observed in these tests. Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR) indicated the addition of functional groups on the fabric after treatment. Micro-Raman spectroscopy (MRS) showed a slight distortion in the structure of the CF due to the treatment. Increased roughness of the fibre surface and adhesion of NPs on the fibre surface were observed by field emission scanning electron microscopy (FESEM). Composites were developed based on untreated and surface-treated CFs by impregnation techniques. The composites were analysed for interlaminar shear strength (ILSS) and a maximum improvement of 61% was observed for the 0.3% concentration of YbF3, followed by a slight decline in ILSS, indicating that it was the optimum dose.

Preparation of polyaniline grafted multiwalled carbon nanotubes and conductive application in polyetherimide

A methodology for improving antistatic property of polyetherimide (PEI) composite using polyaniline (PANI) grafted multi‐walled carbon nanotubes (MWNTs) as conductive medium was proposed. First, the MWNTs grafted with PANI (PANI‐g‐MWNTs) were prepared by in‐situ polymerization in an emulsion system. Subsequently, PANI‐g‐MWNTs were blended with PEI using N‐methyl‐2‐pyrrolidone as solvent. After removing the solvent, the PEI/PANI‐g‐MWNT composite was prepared. As assisted conductive medium, the grafted PANI molecular chains on MWNT surface were dispersed in the PEI matrix to decrease the percolation value of the antistatic composites. The structure and morphology of PANI‐g‐MWNTs were characterized by Fourier transform infrared spectroscopy, transmission electron microscope, thermogravimetric analysis, and X‐ray powder diffraction, respectively. The dispersion of PANI‐g‐MWNTs in PEI matrix was studied by scanning electron microscope. The electrical performance was characterized by highly resistant meter. The volume resistivity of the conductivity percolation threshold was 1.781 × 10−8 S/cm when the loading of PANI‐g‐MWNTs was 1.0 wt%. The conductivity of PANI‐g‐MWNTs/PEI composites was found to be higher than that of pristine MWNTs/PEI composite. Copyright © 2012 John Wiley & Sons, Ltd.

Study on the Interfacial Behavior of Clay-Coated Carbon Fiber-Reinforced PEI Composites

In this article, based on the surface chemical treatment of carbon fiber, a clay coating process was developed for the surface modification of the carbon fiber to obtain a controlled interface between carbon fiber and polyetherimide (PEI) matrix in the composites system. SEM, XPS spectrum and contact angle measure reveal that the clay coating can improve the surface roughness of the carbon fiber surface for a favorable wettability with the matrix, which can also improve the interfacial adhesion of the composites. Experimental results show that the interlaminar shear strength (ILSS) and the three-point bending (TPB) of the composites reinforced by the carbon fiber coated with the clay have been enhanced.

Enhanced electrical conductivity of sodium polyacrylate encapsulated multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWNTs) were grafted with poly (acrylic acid) (PAA) forming PAA-g-MWNTs, which were subsequently neutralized with a sodium hydroxide solution resulting in sodium polyacrylate encapsulated MWNTs (PAANa-g-MWNTs). Then PAANa-g-MWNTs were introduced into polyetherimide (PEI) as an electrically conductive additive. The polymer-encapsulated MWNTs could be finely dispersed in the PEI matrix. Moreover, determinations of the electrical conductivity and electrochemical impedance spectra (EIS) of the nanocomposites indicated that the electrical conductive percolation threshold of PAANa-g-MWNTs in PEI was decreased obviously over that of pristine MWNTs, and partially because of the improved dispersion of the conductive filler, partially because of the joint efforts of the moderate ionic conductivity induced by PAANa with the electronic conductivity by MWNTs in the polymer matrix.

Mechanical, thermal and electrical properties of multi‐walled carbon nanotube/aluminium nitride/polyetherimide nanocomposites

AbstractA series of polyimide‐based nanocomposites containing polyimide‐grafted multi‐walled carbon nanotubes (PI‐g MWCNTs) and silane‐modified ceramic (aluminium nitride (AlN)) were prepared. The mechanical, thermal and electrical properties of hybrid PI‐g MWCNT/AlN/polyetherimide nanocomposites were investigated. After polyimide grafting modification, the PI‐g MWCNTs showed good dispersion and wettability in the polyetherimide matrix and imparted excellent mechanical, electrical and thermal properties. The utilization of the hybrid filler was found to be effective in increasing the thermal conductivity of the composites due to the enhanced connectivity due to the high‐aspect‐ratio MWCNT filler. The use of spherical AlN filler and PI‐g MWCNT filler resulted in composite materials with enhanced thermal conductivity and low coefficient of thermal expansion. Results indicated that the hybrid PI‐g MWCNT and AlN fillers incorporated into the polyetherimide matrix enhanced significantly the thermal stability, thermal conductivity and mechanical properties of the matrix. Copyright © 2012 Society of Chemical Industry

Preparation, characterization and dielectric properties of polyetherimide nanocomposites containing surface-functionalized BaTiO3nanoparticles

Polyetherimide (PEI)/hydroxyl-functionalized barium titanate (BaTiO3) nanocomposite films were successfully prepared through solution-casting followed by subsequent thermal imidization. The results of Fourier transform infrared spectroscopy confirmed that the chemical treatment with hydrogen peroxide (H2O2) could efficiently derive hydroxyl groups on the surface of BaTiO3 nanoparticles. The strong interaction between the hydroxyl-functionalized BaTiO3 and the PEI matrix greatly enhanced the particle dispersion as well as the interfacial adhesion, as evidenced by scanning electron microscopy. The PEI nanocomposite with hydroxyl-functionalized BaTiO3 nanoparticles (50 vol% BaTiO3 loading) showed an increased dielectric permittivity of 52.78 at 1 kHz compared with the dielectric permittivity (33.87) of PEI/raw BaTiO3 composite. The loss tangent was still low (less than 0.03) when the content of hydroxyl-functionalized BaTiO3 was 50 vol%. For PEI/BaTiO3 nanocomposites, the frequency and temperature dependences of the dielectric properties were significantly reduced through functionalizing the surface of BaTiO3 nanoparticles with H2O2. Different theoretical approaches were employed to predict the effective permittivity of the nanocomposite systems and the results are compared with the experimental results. Copyright © 2012 Society of Chemical Industry