Polyetherimide Matrix Research Articles

Influence of specific mechanical energy during compounding in a co-kneader on electrical and rheological properties of multiscale composite materials

Abstract This paper focuses on the effect of different scales of fillers, from nano to macrometer, on the rheological and electrical behaviour of thermoplastic-based composites. Composites based on poly (etherimide) matrix (PEI) with multiscale reinforcement are processed by melting in a co-kneader to disperse homogeneously carbon nanotubes and glass fibers. We clearly demonstrate the strong link between the liquid-solid transition and the electrical conductivity. We show that the specific mechanical energy is a key parameter. Glass fibers allow to increase the electrical conductivity of blends based on carbon nanotubes and to obtain a lower decreasing of conductivity at the liquid transition which takes place in the same time as rheological and electrical parameters.

A new type of [PEI-glycidyl POSS] nanofiltration membrane with enhanced separation and antifouling performance

A new type of polyether-imide (PEI)-based nanofiltration membranes was prepared by introducing octaglycidyloxypropyl-silsesquioxane (Glycidyl POSS) into PEI matrix for heavy metals ions removal from water. The separation performance of fabricated membranes in Na2SO4, Pb(NO3)2, Ni(NO3)2 and Cu(NO3)2 removal from water as well as their flux and antifouling property was evaluated. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) analytical method, atomic force microscope (AFM), porosity contact angle, and water content were also used in membrane characterization. The results indicated higher hydrophilicity, pure water flux (PWF) and salt rejection for PEI-POSS membranes compared to neat PEI ones. The morphological images showed good tuning porosity, finger- and spongy-like structure. The highest porosity observed for [PEI-1 wt% glycidyl POSS] with the best antifouling property. The surface roughness also decreased by incorporating of POSS into PEI matrix. The pure water flux increased from 14.3 (L/m2h) for neat PEI membrane to 36 (L/m2h) for [PEI-0.1 wt% glycidyl POSS]. Moreover, Na2SO4, Pb(NO3)2, Cu(NO3)2 and Ni(NO3)2 rejection measured 78%, 94%, 99%, 42% for [PEI-1 wt% glycidyl POSS] membrane, whereas they were 69%, 44%, 40% and 16% for the virgin PEI membrane, respectively. Results showed a good potential for [PEI-POSS] membrane in Cu and Pb ions removal beside its high PWF and antifouling ability.

Construction of gradient structure in polyetherimide/carbon nanotube nanocomposite foam and its thermal/mechanical property

MWNTs-COOH@Fe3O4 hybrid with ferromagnetism was prepared and polyetherimide (PEI)/MWNTs-COOH@Fe3O4 nanocomposite foams with continuously gradient structure were fabricated via water vapor-induced phase separation (WVIPS) method under a magnetic field. Along the magnetic field direction, a continuously gradient distribution of MWNTs-COOH@Fe3O4 formed in PEI matrix, while the average cell size gradually decreased, the cell wall thickness and apparent density increased, forming gradient cell structure for the foam. Both mechanical property and thermal stability of the foam were improved by introducing MWNTs-COOH@Fe3O4. For the composite foam, the tensile strength, elongation at break and storage modulus decreased along magnetic field direction, due to enrichment and aggregation of MWNTs-COOH@Fe3O4 in strong magnetic field. Meanwhile, tanδ decreased and thermal degradation temperature increased, revealing formation of gradient distribution of thermal and mechanical property in the foam, which showed potential application prospective in aerospace and defense area.

Thermal expansion of clay polymer nanocomposites as a function of aspect ratio and filler content

Different amounts of a low (L/h = 100) and a high aspect ratio (L/h = 22,000) synthetic clay (hectorite) have been compounded into a polyetherimide matrix by solution casting. By applying these fillers with largely different aspect ratios we were able to validate the different and partially contradicting models found in the literature to predict coefficients of thermal expansion (CTE) of nanocomposites. A comparison with experimentally observed CTEs identified Lu's model to give the best agreement. In this model, the CTE is highly non-linear in respect to both the aspect ratio and the filler content allowing to identify technically benign combinations that assure a given target-CTE. For instance, for printed circuit boards made of thermoplastic PEI, an aspect ratio of around 1000 and a filler content of about 13 vol% are predicted to perfectly match the CTE of the nanocomposite to the CTE of copper while maintaining processability.

Green Hydrogen Separation from Nitrogen by Mixed-Matrix Membranes Consisting of Nanosized Sodalite Crystals.

Nanosized sodalite (Nano-SOD) crystals were used as active filler to prepare mixed-matrix membranes (MMMs) for promoting the H2 /N2 gas-separation performance. The Nano-SOD crystals with extremely small crystallites (40-50 nm) were synthesized from a colloidal suspension free of organic structural directing agent and uniformly dispersed in the polyetherimide (PEI) matrix. The Nano-SOD filler with a suitable aperture size (2.8 Å) allowed only H2 molecules to pass through and rejected the N2 , thus improving the selectivity of the membranes. The high dispersion of Nano-SOD crystals in the polymer matrix and the interactions between the inorganic and organic phases greatly improved the membrane separation performance and minimized interfacial holes. The MMMs showed a high H2 permeability (≈7155.1 Barrer at 25 °C under atmospheric pressure) and an ideal H2 /N2 selectivity factor of approximately 16.9 in a single gas test. Moreover, in a gas mixture (H2 /N2 , 25-100 °C), the selectivity factor increased significantly to approximately 30.9. The high stability of the MMMs, which consist of highly dispersed Nano-SOD crystals in a PEI matrix for H2 /N2 separation (6 weeks continuous test), makes them an important material for ammonia synthesis applications that require and also release a large amount of H2 .

Exploration of potential of Zylon and Aramid fibers to enhance the abrasive wear performance of polymers

Two series of composites based on two types of high performance fibers (aramid and liquid-crystalline polyoxazole) were developed by using two different base matrices viz. Polyetherimide (PEI) and Ultra-high-molecular-weight-polyethylene (UHMWPE). PEI based composites reinforced with fabrics of Zylon (liquid-crystalline polyoxazole) and Kevlar-49 (aramid) were developed by using an impregnation technique, while UHMWPE composite reinforced with fibers of Twaron (aramid) was developed by a novel co-mingling technique. These composites were evaluated for their abrasive wear performance under various loads and orientations against Silicon Carbide (SiC) abrasive paper in a single pass condition. These fabric reinforcements enhanced the abrasive wear performance up to 50% when the fabric was oriented normal to the sliding surface. However, the wear performance deteriorated when the fabric was oriented parallel to the sliding surface. Zylon fabric proved to be the most beneficial in maximizing the wear resistance of PEI matrix. These results were supported by the SEM studies done to understand the various possible wear mechanisms.

Development of high temperature electrical conductive polymeric nanocomposite films for aerospace applications

In this investigation, an effort has been made to develop an electrically conductive high performance thermoplastic polyetherimide (PEI) nanocomposite film by reinforcing carbon nano fibers (CNF). PEI reinforced with silver coated CNF nanocomposite films have been processed using a solution casting technique. The electrical conductivity of the nanocomposite films has been characterized using four-point probe test. The results reveal that there is a significant increase in the electrical conductivity of the PEI/Ag coated CNF nanocomposite film when compared to that of unfilled PEI. Tensile test results showed that there is a marginal improvement in the Ag coated CNF/PEI nanocomposite when compared to unfilled PEI films. Thermogravimetric (TGA) analysis shows that degradation properties of the Ag-coated CNF filled nanocomposite increases. Spectroscopical analysis spectrum confirms the reinforcing effectiveness of Ag-coated CNF in the PEI matrix. Scanning Electron Microscope (SEM) micrographs validated the dispersion of uncoated and coated CNF in the PEI matrix.

Microcellular polyetherimide/graphene‐polysiloxane composite foam: intercalation structure, mechanical and thermal properties

AbstractBased on the industrialized reduced graphene oxide (RGO) product, polyetherimide (PEI)/RGO composite foam was prepared by a water‐vapor‐induced phase separation process by incorporation of polysiloxane (SI) as a compatibilizer. It was found that PEI/SI molecules were intercalated into the RGO layers through strong interfacial interaction and RGO with increased layer thickness was uniformly distributed in the PEI matrix. The composite foam possessed a homogeneous spherical‐like cell structure with narrow cell size distribution and low apparent density. In the range of 0–1 wt% RGO‐SI content, the area under the stress–strain curves increased dramatically, indicating the significantly increased toughness of the composite foam, while the tensile strength reached a maximum of 14.5 MPa at 1 wt% RGO‐SI as a result of the reinforcing effect of RGO‐SI on the foam. The addition of RGO‐SI led to a remarkable increase in Tg. Compared with neat PEI foam, the thermal degradation temperature and char yield of the composite foam clearly increased, while in the range of 0.5–3 wt% RGO‐SI a high storage modulus was maintained at high temperature, reaching about 300 MPa at 200 °C, indicating a remarkable improvement of the thermal mechanical stability of the foam. © 2018 Society of Chemical Industry

Multifunctional silanized silica nanoparticle functionalized graphene oxide: polyetherimide composite film for EMI shielding applications

Synthesis of graphene oxide (GO) was done using graphite powder by Hummer’s modified method and it was functionalized using silanized silica nanoparticle. Various weight percentage of functionalized graphene oxide (FGO) in polyetherimide (PEI) matrix (0.5–3 wt%) nanocomposite films were synthesized using solution based method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies confirm the functionalization and partial reduction of GO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies demonstrated the nanostructure of GO, FGO and PEI–FGO nanocomposite films. The electromagnetic interference (EMI) shielding effectiveness in comparison to pure polyetherimide (2–3 dB), nanocomposite with 1.5 wt% FGO loading exhibits upto 21–23 dB at frequency range 8–12 GHz. Dynamic mechanical analysis (DMA) elucidate the improvement of glass transition temperature and storage modulus (E′) of the PEI–FGO nanocomposite films. Variation in different experimental parameters such as frequency, temperature and filler loading were used to analyze the dielectric properties of the PEI–FGO nanocomposite films. Dielectric constant increases seven times and dielectric loss decreases 14 times for nanocomposites with 1.5 wt% FGO loading in PEI matrix as compared to pure polyetherimide. The bandgap decreases slightly for PEI–FGO composite due to an intermediate band in PEI band structure by FGO. The nanocomposite films also exhibited good dielectric, mechanical properties and excellent EMI shielding effectiveness at wide range of frequency and temperature.

Polyetherimide-montmorillonite mixed matrix hollow fibre membranes: Effect of inorganic/organic montmorillonite on CO2/CH4 separation

Abstract Hollow fibre mixed matrix (HFMM) membranes with nano-filler embedded in polymer matrix offer an attractive route for the fabrication of high performance gas separation membranes. However, the quest to achieve high performance mixed matrix membranes remains a challenge without acquiring even filler distribution in polymer matrix. In this work, HFMM membranes comprising polyetherimide (PEI) with various inorganic and organic montmorillonite (I-MMT and O-MMT) loadings ranging from 1 to 4 wt%, were developed via phase inversion method and coated with PDMS for CO2/CH4 separation. Morphological, filler distribution, dispersion, surface topology and gas separation studies were carried out for developed hollow fibre (HF) membranes. Pure gases (CO2 and CH4) were used at varying pressure of 2–10 bars at ambient conditions. In addition, mixed gas test at CO2/CH4 composition of 50/50 v/v % was carried out for selected membranes. Upon incorporation of I-MMT, the developed mixed matrix membranes (MMMs) showed decrease in CO2/CH4 gas separation performance compared to neat PEI membrane. In contrast, the performance of asymmetric membrane was enhanced by incorporating O-MMT in PEI matrix to form MMMs. Uniform dispersion, void-free morphology and reduced surface roughness were observed for the aforementioned membranes. Furthermore, an increasing trend in ideal selectivity was observed up to 2 wt% O-MMT loading against all feed pressures. Thereafter, opposite trend was observed with increasing filler loading due to filler agglomeration. The maximum ideal selectivity achieved was 18.35 with 2 wt% loading at 4 bar pressure which is 52.2% higher than neat PEI hollow fibre membrane.

Processibility and Thermo-Mechanical Properties of Epoxy as Reactive Plasticizer of Polyetherimide

A relatively new way to improve processibility thermoplastics is via the use of crosslinkable monomers which can act as reactive plasticizers and reduce the viscosity in the early stage of processing. The monomers can polymerize and phase separate during final stage of processing thus recovering the original thermoplastics properties. In this work, the applicability of epoxy as reactive plasticizer for polyetherimide (PEI) was investigated. The properties of PEI/epoxy blends without and with curative were studied in order to determine the effect of the monomer on the processibility of the PEI and the thermo-mechanical properties of cured blends. Differential Scanning Calorimetry on blends without curative indicated single glass transition temperature (Tg) at high PEI content suggesting miscibility of the system and plasticization of PEI in the presence of epoxy while cured blends indicated two Tg due to phase separation. Scanning electron microscopy of the cured blends indicated two phase morphology with PEI dispersed particles size increased in continuous epoxy matrix with increasing PEI (up to 30wt% PEI). In blends with 40wt% PEI and more, phase inverted morphology was observed where increasing PEI content caused reduction of epoxy particle size in continuous PEI matrix.

Solid‐state microcellular high temperature vulcanized (HTV) silicone rubber foam with carbon dioxide

ABSTRACTA series of microcellular high temperature vulcanized (HTV) silicone rubber foams were prepared using CO2 as a physical blowing agent. Rheological properties, gas diffusive behavior, and foaming parameters of silicone rubber were investigated. The results show that saturation pressure has a significant effect on the diffusivity of CO2 in HTV silicone rubber matrix. The gas concentration and diffusivity increase from 2.45 wt % to 3.24 wt %, and from 1.62 × 10−5 cm2/s to 7.83 × 10−5 cm2/s as the saturation pressure increases from 2 MPa to 5 MPa, respectively. The value of the gas diffusivity in HTV silicone rubber is almost 1000 times higher than that of the gas diffusivity in polyetherimide (PEI) matrix. Additionally, microcellular HTV silicone rubber foams with the smallest cell diameter of 9.8 μm and cell density exceeding 108 cells/cm3 are achieved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44807.

Preparation of double-coated TiO2 nanoparticles using an anchoring grafting method and investigation of the UV resistance of its reinforced PEI film

TiO2 nanoparticles were modified with 3-methacryloxypropyltrimethoxysilane (γ-MPS) and polyetherimide (PEI) in N-methyl-2-pyrrolidone (NMP) using an anchoring grafting method. The modified nanoparticles (TMP) were characterized using Fourier-transform infared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric and differential thermal analysis (TG-DTA) and transmission electron microscopy (TEM), and were found to be successfully coated by γ-MPS and PEI layers. The dispersion-sedimentation mechanism that occurred in the modification of the TiO2 nanoparticles was examined and explained using a dispersion stability test. Nanocomposite films (TMP/PEI) that contained TMP nanoparticle as a filler material within a PEI matrix were also fabricated. Compared with traditional TiO2/PEI nanocomposite films, the TMP/PEI film exhibited improved tensile strength and tensile modulus, both before and after UV radiation.

Synthesis of non-destructive amido group functionalized multi-walled carbon nanotubes and their application in antistatic and thermal conductive polyetherimide matrix nanocomposites

Thermal conductive and antistatic polyetherimide (PEI) nanocomposites were fabricated by encapsulating non-destructive amido group functionalized multi-walled carbon nanotubes (MWCNTs) into the PEI matrix. Briefly, nearly half of acyl chloride groups in poly (acryloyl chloride) reacted with sodium azide and formed acyl azide groups, which could conjunct with MWCNTs via non-destruction nitrenes addition reaction. The remaining acyl chloride groups in poly (acryloyl chloride) hydrolyzed into carboxyl groups, therefore COOH-rich MWCNTs (MWCNTs@azide polyacrylic acid) were synthesized without serious damage to the MWCNTs. Then, MWCNTs@azide polyacrylic acid were then reacted with p-Phenylene diamine (PPD) and transformed to amido group functionalized MWCNTs (MWCNTs@PPD). MWCNTs@PPD could participate into the in situ polymerization of PEI matrix, where the conjunction between bisphenol A dianhydride and amido groups on MWCNTs@PPD guaranteed the strong covalent bonding at the PEI/MWCNTs interface, which directly avoided the aggregation of MWCNTs. Owing to the non-destructive modification of MWCNTs and tight matrix/filler interface, the volume electric and thermal conductivity of as-prepared nanocomposites was up to 6.4 × 10−8 S/cm (1.0 wt%, MWCNTs@PPD) and 0.43 W/(m · K) (4.0 wt%, MWCNTs@PPD), respectively. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of hydrogen plasma-mediated surface modification of carbon fibers on the mechanical properties of carbon-fiber-reinforced polyetherimide composites

The surfaces of carbon fibers were modified by hydrogen plasma treatment to investigate the consequent effects on reinforcement of polyetherimide (PEI) composites. The structural surface properties were characterized by Raman spectroscopy, XPS, FT-IR and SEM. The effectiveness of hydrogen and oxygen plasma treatments in improving the surface roughness, structure and mechanical properties of the composites was demonstrated. The results indicated that hydrogen and oxygen plasma treatment modified the carbon bonding structure and the surface roughness differently. Both an increase in the density of functional groups and changes in the carbon bonding contributed to the enhancement of the PEI matrix. SEM imaging confirmed decreased fiber pull-out for PEI reinforced with plasma-treated carbon fibers because of the enhanced adhesion between the carbon fibers and the PEI. Thus, hydrogen plasma treatment of the carbon fibers led to an enhancement of tensile properties at both room temperature and high temperature (150 °C). This study demonstrates that hydrogen plasma treatment is a promising technique for improving the mechanical properties of carbon-fiber-reinforced polymer composites.

Solid-state polyetherimide (PEI) nanofoams: the influence of the compatibility of nucleation agent on the cellular morphology

The introduction of polyhedral oligomeric silsesquioxane (POSS) particles which act as heterogeneous nucleation agent was applied to improve the cellular morphology of nanocellular polyetherimide (PEI) foams. The loading of POSS particles increases the solubility and diffusivity characteristics of gases in nanocomposite sheets by changing the distribution of the free volume and enlarging the unoccupied volume in polymer matrix. When the range of content of POSS particles is 0.2 ~ 1.0 wt. %, the range of the calculated surface tension of PEI/scCO2 (γ mix ) and radius of the critical nucleus (r*) are 30.98 ~ 28.14 mN/m, and 6.88 ~ 6.25 nm, respectively. However, the small aggregated POSS particles are favour of heterogeneous nucleation bacause the actual diameter of the aggregated POSS particles is approximate to twice r*, so the addtion of 0.5 wt. % POSS to PEI matrix presents excellent heterogeneous nucleation performance for foaming. The average cell size of 0.5 wt. % POSS/PEI nanofoams compared with neat PEI decreases from 108 to 66 nm and the cell density increses from 5.96 × 1014 to 3.34 × 1015 cells/cm3.

Corrosion inhibition of copper in sodium chloride solution using polyetherimide/graphene composites

AbstractIn this study, polyetherimide‐graphene composites (PEI/G) were prepared and investigated as corrosion inhibition coatings on copper substrates. Various loadings of graphene were incorporated in the polyetherimide matrix using an in situ polymerization approach, and the composite coatings were cured by thermal imidization. The effect of graphene loading on corrosion inhibition and the long‐term performance of the PEI/G coatings were investigated. The dispersion of graphene in the polymer matrix was examined using SEM and TEM. The study demonstrated that PEI/G nanocomposites provide advanced corrosion inhibition of copper. This conclusion was supported by the results of various electrochemical techniques such as Tafel polarization and electrochemical impedance spectroscopy (EIS). In addition to corrosion protection, the long‐term performance of the coatings was confirmed by testing the adhesion of PEI/G composites to copper substrates before conducting the electrochemical tests and after 15 days of exposure to the corrosive medium.

Gas transport in metal organic framework–polyetherimide mixed matrix membranes: The role of the polyetherimide backbone structure

We report on how the morphology of the polymer matrix, i.e. amorphous vs. semi-crystalline, affects the gas transport properties in a series of mixed matrix membranes (MMMs) using Cu3(BTC)2 as the metal organic framework (MOF) filler. The aim of our work is to demonstrate how incorporation of Cu3(BTC)2 affects the polyetherimide matrix morphology and thereby highlighting the importance of selecting the appropriate polyetherimide matrix for mixed matrix membranes.We used three amorphous poly(etherimide)s with very similar backbone structures. Polyetherimide ODPA-P1 was used as a linear flexible matrix, aBPDA-P1 is a non-linear rigid matrix and 6FDA-P1 was selected because the backbone structure is similar to ODPA-P1 but replacing the oxygen linker with two bulky –CF3 groups results in a linear polymer with a low chain packing efficiency. Using an in-situ polymerization technique, up to 20 wt.% Cu3(BTC)2 could be homogenously dispersed in all three PEIs. The ODPA-P1 matrix crystallized when Cu3(BTC)2 was introduced as a filler. Gas permeation studies were performed by analyzing membrane performance using a 50:50 CO2:CH4 mixed gas feed. The presence of crystalline domains in ODPA-P1 resulted in a decrease in permeability for both CO2 and CH4 but the selectivity increased from 41 to 52 at 20 wt.% Cu3(BTC)2. The non-linear, rigid, aBPDA-P1 matrix remains amorphous when Cu3(BTC)2 is introduced. SEM images of the MMM cross-section revealed a sieve-in-a-cage morphology and at 20 wt.% Cu3(BTC)2, the permeation of both CO2 and CH4 increased by 68% thereby negating any change in selectivity. For 6FDA-P1 with 20 wt.% Cu3(BTC)2, only the permeability of CO2 increased by 68% resulting in an increase in selectivity of 33%.

전기방사에 의한 폴리에테르이미드(PEI)-MWCNT 복합섬유의 제조 및 물성에 대한 연구

We have prepared multi-walled carbon nanotube (MWCNT)-embedded conductive composite fibers using polyetherimide (PEI) as a polymer matrix (denoted as PEI-MWCNT). Uniform dispersion of the MWCNTs in dimethylacetamide was achieved after functionalization with quadruple hydrogen bonding sites, after which conductive composite fibers were produced via an electrospinning process. PEI-MWCNT fibers were prepared containing up to 3 wt% MWCNTs, and the resulting fibers were analyzed in order to determine the diameter and electrical conductivity of the fibers. Analysis of the fibers with scanning electron microscopy (SEM) revealed highly porous fiber structures, and that the MWCNTs were well-dispersed within the PEI matrix. Increasing the amount of MWCNTs in the fiber resulted in a decrease in the average fiber diameter, and the electrical conductivity was improved even when only a small amount of functionalized MWCNT was present.

Friction and wear studies of polyetherimide composites under oscillating sliding condition against steel cylinder

Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120°C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported. POLYM. COMPOS., 38:48–60, 2017. © 2015 Society of Plastics Engineers