Fibre-reinforced Polyetherimide Research Articles

Improved creep resistance of short carbon fiber reinforced polyetherimide composite by solution mixing method

Creep resistance is critical for ensuring the dimensional stability and safe operation of composite components. However, the creep resistance of short fiber reinforced thermoplastic composites has been rarely reported and that of the composites manufactured by conventional extrusion compounding combined with injection molding is kind of low. In this work, in order to address this issue, two short carbon fiber-reinforced polyetherimide (SCF/PEI) composites named respectively as SCF/PEIE and SCF/PEIS are prepared by both conventional extrusion compounding and our newly developed solution mixing method combined with injection molding. The solution mixing method involves the dispersion and mixing of carbon fibers within a PEI solution and allows for the retention of longer fiber lengths. Experimentally, the creep behaviors of the SCF/PEI composites were examined through tensile and flexural creep testing at various stress levels in a wide temperature range. Theoretically, the creep behaviors were characterized by employing the Schapery model and the time–temperature superposition principle (TTSP), and the impact of fiber length retention on creep resistance was quantitatively analyzed using the Fu-Lauke model. The results demonstrate that compared to the SCF/PEIE composite, the SCF/PEIS composite exhibits a higher creep fracture stress level (175 MPa) and a more extensive linear viscoelastic region (0 ∼ 85 MPa) at room temperature. Furthermore, the SCF/PEIS composite was observed to have a significantly longer secondary creep stage at an elevated temperature of 210 °C. Overall, the creep resistance of the newly manufactured SCF/PEIS is significantly superior to that of the SCF/PEIE, which effectively extends the service life and operational capacity of injection-molded SCF/PEI composites.

Fiber dispersion as a quality assessment metric for pultruded thermoplastic composites

Fiber-reinforced polymer composites are often assessed by measuring void content via thresholding of optical microscope cross-sectional images, relying on contrast to differentiate between voids and surrounding material. This is effective when dealing with primarily closed voids, a characteristic common to thermoset matrix composites. However, composites that exhibit fiber impregnation issues, often due to high matrix viscosity as in thermoplastic composites, will typically contain open pores which are infiltrated by the mounting resin used to embed the sample for grinding and polishing. Voids filled with this resin can be difficult to optically distinguish from the matrix, leading to inaccurate void content measurements. To circumvent this, a strategy for assessing impregnation quality based on fiber dispersion is proposed. During impregnation processes, the fiber network exhibits a tendency to become locally compacted by flow fronts, leading to low permeability regions with fiber clusters that are less likely to become fully impregnated. Fiber dispersion quantifies the percentage of non-clustered fibers from positional data and provides information on degree of impregnation and the locations of interfiber voids. The effects of processing speed and temperature on fiber dispersion are investigated in the production of continuous carbon fiber-reinforced polyetherimide (PEI) additive manufacturing feedstock material from commingled yarn using multi-die pultrusion. Fiber dispersion is observed to increase with slower pultrusion speeds, correlating with higher flexural strength and stiffness properties. This increase in fiber dispersion with longer die residency time indicates that the decompaction of fiber clusters is highly time-dependent and occurs by migration of fibers away from cluster boundaries.

Study on YB-laser welding applied on aluminum/polymer composites

In the present study, an anodizing process was applied to aluminum alloy (AA2024-T3) to enhance interlocking in dissimilar joints with glass fiber-reinforced polyetherimide (GF/PEI) composite, using ytterbium-doped laser fiber welding as a heat source. A factorial Central Composite Design (CCD) was conducted to determine the most appropriate processing and optimization parameters, with lap shear strength (LSS) as the response variable. The obtained and fractured joints were characterized. Anodizing effectively improved the interlocking between dissimilar joints, resulting in LSS values of around 16 MPa. Surface impressions were observed in joints with lower shear values, likely due to the ineffective heat distribution in the processed joint. In the AA2024-T3 alloy, the annealing process occurred, beginning with the segregation of the alloy elements at the grain boundaries and subsequently reducing its hardness. The SEM analysis of the laminate in the best welding condition revealed a well-established fracture surface, with cusps, fibers covered by the polymer matrix, and river marks, indicating good consolidation of the process applied to the metal/polymer junction, which is consistent with the highest shear values obtained. These findings have important implications for future research and industrial applications and can help advance the understanding of these materials and processes.

Impact study of a car bumper by using carbon fiber reinforced polyetherimid and S-glass/ epoxy composite

Bumper plays a major role to prevent the impact forces vehicles during collisions. It's miles the front-maximum or uncommon-most part, designed to allow the auto to preserve an impact without harm to the automobile’s protection structures. Also, the fuel efficiency is an important issue these days. Bumper is one of the heavier parts of a car. So, in this we're targeting cloth optimization for Bumper via performing impact analysis to reduce the load and to finalize the appropriate cloth for the bumper having the higher absorption homes. The whole analysis method accommodates of degrees, which might be conceptual design of Bumper the use of Autodesk Inventor and guidance of Bumper for numerical evaluation in Ansys 19.2. right here the auto bumper is analyzed by using changing its modern material Aluminum by means of composites Carbon fiber reinforced poly ether imide (PEI) and S-glass epoxy substances at 3 unique velocities: eighty kmph, a hundred kmph and a hundred and twenty kmph. After thorough commentary of effects, the high-quality appropriate cloth is finalized for the bumper.

Fabrication of continuous carbon fibre-reinforced polyetherimide through fused filament fabrication

Fabrication of continuous carbon fibre-reinforced polyetherimide through fused filament fabrication

Stress Distributions for Hybrid Composite Endodontic Post Designs with and without a Ferrule: FEA Study.

The aim of the current work was to analyze the influence of the ferrule effect for hybrid composite endodontic post designs consisting of carbon (C) and glass (G) fiber-reinforced polyetherimide (PEI), in upper canine teeth. Starting from theoretical designs of C-G/PEI hybrid composite posts with different Young’s moduli (Post A—57.7 GPa, Post B—31.6 GPa, Post C—graduated from 57.7 to 9.0 GPa in the coronal–apical direction) in endodontically treated anterior teeth, the influence of the ferrule effect was determined through finite element analysis (FEA). On the surface of the crown, a load of 50 N was applied at 45° to the longitudinal axis of the tooth. Maximum principal stresses were evaluated along the C-G/PEI post as well as at the interface between the surrounding tooth structure and the post. Maximum stress values were lower than those obtained for the corresponding models without a ferrule. The presence of a ferrule led to a marked decrease of stress and gradients especially for posts A and B. A less marked effect was globally found for Post C, except in a cervical margin section along a specific direction, where a significant decrease of the stress was probably due to local geometric features, compared to the model without a ferrule. The presence of a ferrule did not generally provide a marked benefit in the case of the graduated Post C, in comparison to other C-G/PEI posts. The outcomes suggest how such a hybrid composite post alone should be sufficient to optimize the stress distribution, dissipating stress from the coronal to the apical end.

The influence of dynamic rheological properties on carbon fiber-reinforced polyetherimide for large-scale extrusion-based additive manufacturing

Printing high-performance thermoplastics on large scale extrusion-based additive manufacturing platforms requires stability over a range of processing conditions. However, studies on the melt dynamics and processing conditions of these thermoplastics in big area additive manufacturing (BAAM) are limited. This study characterizes the dynamic rheological behavior of polyetherimide (PEI), a high-performance thermoplastic, as well as carbon fiber (CF)-reinforced PEI composites as a BAAM feedstock material. The viscoelastic properties, such as the storage and loss moduli and complex viscosity, are investigated in relation to the BAAM extrusion process. The results show that CF-PEI composites behave like a viscous liquid during BAAM extrusion. The addition of CF to PEI enhances the shear thinning effect and significantly increases the complex viscosity (2.5× increase for 20% CF, and 3× for 30% CF). The increased viscosity increases the torque on the extruder, which may be alleviated by increasing the material processing temperature.

Friction spot welding of carbon fiber-reinforced polyetherimide laminate

Here, carbon fiber-reinforced polyetherimide (PEI) laminate was joined via friction spot welding (FSpW). The feasibility and fracture mechanism of the FSpW joints were investigated. The sound joint with smooth surface and without hook defect was achieved. The strong bonding formed at the sleeve stirring zone and thermo-mechanically affected zone, resulting from the macromolecular interdiffusion and interlocking of the smashed carbon fiber at the bonding interface by thermo-mechanical behavior. Increasing rotational velocity enhanced the mixing degree of the carbon fiber at the interface and strengthened the bonding interface, which improved tensile shear properties. The maximum tensile shear load of the FSpW joint with a joining area of 66.4 mm2 reached 1600 N, which was comparable to the strength of state-of-the-art welding. The fracture surface morphologies revealed a typical ductile fracture containing the deformation of polymer and the pull-out of the carbon fiber. The FSpW has feasible and potential to join carbon fiber-reinforced thermoplastic composites laminate.

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.

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.

Influence of fibre orientation on three-body abrasive wear behaviour of unidirectional carbon fibre-reinforced polyetherimide composite

Three-body abrasive wear behaviour of neat polyetherimide (PEI) and unidirectional carbon fibre-reinforced PEI (CF/PEI) has been studied using a rubber wheel abrasion test rig. The abrasive wear studies were carried out at different loads (5–20 N) at a constant sliding velocity (v = 2.4 m/s) of rubber wheel. The influence of fibre orientation, i.e. parallel (P-fibre orientation) and anti-parallel (AP-fibre orientation) on wear rate of CF/PEI composite has also been studied. The results showed that the fibre orientation has a significant influence on the three-body abrasive wear behaviour of CF/PEI. The abrasive wear rate was higher when fibres are oriented at anti-parallel than that of parallel orientation of fibres. The worn surfaces have been observed using scanning electron microscope to understand the possible wear mechanisms involved during material removal processes.

Impact–fatigue behaviour of unidirectional carbon fibre reinforced polyetherimide (PEI) composites

Impact fatigue properties of unidirectional carbon fibre-reinforced polyetherimide (PEI) composites was evaluated by subjecting standard izod impact samples to low velocity impact loading at energy levels ranging 0.16–1.08 J by using Ceast Model Resil 25, a pendulum type instrumented impact test system. The effect of the previous low velocity impacts on the impact properties of the laminates was investigated. On the other hand materials were subjected to repeated low velocity impact tests up to fracture. Results of repeated impact study are reported in terms of peak load, absorbed energy and number of impacts. Fractographic analysis revealed the fracture by primary debonding, with fibre breakage and pullout in the tensile zone, but a shear fracture of fibre bundles in the compressive zone of the specimen.

Development of a Numerical Model to Predict In-Plane Heat Generation Patterns During Induction Processing of Carbon Fiber-Reinforced Prepreg Stacks

A numerical model is proposed to describe in-plane heat generation spatial response during induction processing of carbon fiber-reinforced thermoplastics. The model is based on a unified approach that considers three possible heating mechanisms: fiber heating (Joule losses in fiber), noncontact junction heating (dielectric hysteresis), and contact junction heating (Joule losses at junctions). A lumped meshing scheme is used to construct a numerical representation for cross-ply and angle-ply orientations of 2-ply prepreg stacks. Heat generation patterns are calculated based on voltage and current conservation laws and verified with induction heating of AS4 carbon fiber-reinforced polyetherimide (AS4/PEI) prepreg stacks. Excellent agreement is found except at very low angle-ply orientations where the predicted heating patterns show significant deviations from the experiment results. A sensitivity analysis is also performed to assess the relationship between heating patterns and material and process parameters. The results show that the stack angle between plies and intrinsic prepreg microstructure can significantly affect the heating patterns.

Interfacial Adhesion and Microfailure Modes of Electrodeposited Carbon Fiber/Epoxy–PEI Composites by Microdroplet and Surface Wettability Tests

Interfacial properties and microfailure modes of electrodeposition (ED)-treated carbon fiber-reinforced polyetherimide (PEI) toughened epoxy composite were investigated using microdroplet test and the measurement of surface wettability. ED was performed to improve the interfacial shear strength (IFSS). As PEI content increased, IFSS increased due to enhanced toughness and plastic deformation of PEI. In the untreated case, IFSS increased with adding PEI content, and the IFSS of the pure PEI matrix showed the highest. On the other hand, for the ED-treated case IFSS increased with PEI content with rather low improvement rate. In the untreated case, neat epoxy resin appeared brittle microfailure mode, whereas the pure PEI matrix exhibited a more likely ductile microfailure mode. In the ED-treated case, neat epoxy exhibited a more ductile fracture than that of the untreated case. Critical surface tension and polar surface free energy of ED-treated carbon fiber was higher than those of the untreated fiber. The work of adhesion between fiber and matrix was not directly proportional to IFSS for both the untreated and ED-treated cases. The matrix toughness might contribute to IFSS more likely than the surface wettability. Interfacial properties of the epoxy–PEI composite can be affected efficiently by both the control of matrix toughness and ED treatment.

Prediction of the consolidation of woven fibre-reinforced thermoplastic composites. Part I. Isothermal case

The mechanisms involved in the isothermal consolidation of woven carbon fibre-reinforced polyetherimide (PEI/WCF) have been studied. Press-formed samples were processed in a matched-die mould equipped with pressure and temperature transducers. Optical microscopy and fracture tests were used to determine the evolution of consolidation as a function of three processing parameters namely pressure, temperature and time. The mechanisms of intimate contact and fibre impregnation were found to be responsible for void resorption. At normal processing temperatures the inter-ply interfacial strength is governed by resin flow at the interface and the mechanism of fibre impregnation limits the rate of consolidation. A model which accounts for resin flow through the fibre bed, for the formation of intimate contact and for autohesion between adjacent plies has been proposed to predict the consolidation of PEI/WCF. Predictions obtained using this model have shown good agreement with experimental results.

An experimental nose-wheel door of continuous fibre-reinforced thermoplastic

To gain experience with continuous fibre-reinforced thermoplastics, an attractive new family of composite materials, an experimental nosewheel door has been designed, manufactured and tested in aramid fibre-reinforced polyetherimide.