Search

Various contents of carbon fibers (CFs) and potassium titanate whiskers (PTWs) were added to an Fe-based impregnated diamond bit (IDB) matrix to enhance its adaptability to percussive–rotary drilling. A series of mechanical tests were conducted successively to find the effects of the reinforcing materials on the properties of the Fe-based IDB samples. Then, the fracture surfaces of the samples were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy, and the worn surfaces and abrasive debris of the samples were analyzed using a laser scanning confocal microscope and SEM. The results show that both the CF and PTW can effectively improve the hardness and bending strength of an Fe-based IDB matrix, and those parameters reached their maximum values at the additive amount of 1 wt%. However, the CF had a better enhancement effect than the PTW. Furthermore, the CF improved the impact wear resistance of the IDB matrix, with a minimum wear rate of 2.38 g/min at the additive amount of 2 wt%. However, the PTW continuously weakened the impact wear resistance of the IDB matrix with increases in its content. Moreover, the morphologies of the worn surfaces indicated that the minimum roughness of the CF-reinforced IDB matrix decreased significantly to as low as 4.91 μm, which was 46.16% lower than that without CF, whereas the minimum roughness of the PTW-reinforced samples decreased by 11.31%. Meanwhile, the abrasive debris of the CF-reinforced samples was more uniform and continuous compared to that of the PTW-reinforced samples. Overall, the appropriate addition of CF or PTWs can enhance the mechanical properties of Fe-based IDB matrices, which can be used on different formations based on their impact wear resistance. [ABSTRACT FROM AUTHOR]

The fretting wear behavior of fluorine rubber (FKM) and short carbon fiber (SCF) reinforced fluorine rubber matrix composites (SCF/FKMCs) is investigated experimentally under air condition. Four kinds of SCF/FKMCs with different SCF concentrations (5 phr, 10 phr, 15 phr, and 20 phr in every 100 phr of FKM) are considered. The contact model utilizes the sphere-on-flat contact between a 440 C stainless steel ball and an FKM or SCF/FKMCs coating perfectly bonded to a ceramic sheet in fretting experiments. The impacts of SCF concentration, normal force, and displacement amplitude on the fretting wear behavior are investigated. Scanning electron microscope (SEM) is used to analyze the fretting wear surface morphology and wear mechanism, while three-dimensional (3D) white-light interference profilometer is used to describe the characteristics of 3D surface wear profile and determine the wear volume. The fretting wear performances of FKM and SCF/FKMCs with different SCF concentrations are compared under different fretting test conditions. The results show that adding an appropriate amount of SCFs to FKM can improve wear resistance and reduce the coefficient of friction (COF). SCF/FKMC with SCF concentration of 15 phr has the smallest COF. SCF/FKMCs with SCF concentration of 5 phr or 15 phr have the best wear resistance for small normal force or large displacement amplitude. [ABSTRACT FROM AUTHOR]

Large-tow carbon fiber (LCF) meets the low-cost requirements of modern industry. However, due to the large and dense number of monofilaments, there are problems with uneven and insufficient infiltration during material preparation. The permeability of large-tow carbon fibers can be used as a two-scale expression of resin flow during infiltration, making it an important factor to consider. This paper provides support for the study of pore formation. A two-dimensional model of randomly bundled large-filament carbon fibers is generated based on scanning electron microscope (SEM) maps. Microstructure size parameters are obtained, and a semi-analytical model of the transverse permeability of large-filament-bundled carbon fibers is established. Permeability values are then obtained. The analysis shows that the monofilaments in the tow are arranged randomly, and their periodic arrangement cannot be used to calculate permeability. Additionally, the number of monofilaments in a carbon fiber tow of the same volume fraction affects the permeability of the tow. Therefore, the permeability model of large-tow carbon fibers is reliable. [ABSTRACT FROM AUTHOR]

In this present study, the fused deposition modeling (FDM) method was used to fabricate the composites. Before three-dimensional (3D) printing, samples were designed according to the ASTM D256, D790 and D3039 standards for impact, flexural and tensile tests, respectively, using Onshape software before conversion to an STL file format. Afterward, the digital file was sliced with infill densities of 60%, 80%, and 100%. The composite samples contained chopped carbon fiber (cCF) and poly lactic acid (PLA), as reinforcement and matrix, respectively. The cCF/PLA (simply called cCFP) filaments were printed into various cCFP composite (cCFPC) samples, using a Viper Share bot 3D machine with different infill densities before the aforementioned mechanical testing. The tensile strength of cCFP were obtained as 25.9MPa, 26.9MPa and 34.75MPa for 60%, 80% and 100% infill density cCFP samples, respectively. Similarly, the flexural strength of cCFP were obtained as 11.8MPa, 12.55MPa and 18.4MPa and impact strength was 47.48kJ/m2, 48.45kJ/m2 and 48.96kJ/m2 for 60%, 80% and 100% infill density cCFP samples, respectively. The fractured/tested samples were examined and analyzed under a scanning electron microscope (SEM) to investigate the presence of fiber and void in the tensile sample. Based on the experimental results, it was evident that a high infill density of 100% with the highest reinforcement exhibited maximum impact strength, tensile and flexural strengths and moduli when compared with other lower carbon content of cCFPC samples. Therefore, the optimal 3D-printed cCFPC sample could be used for engineering application to benefit from properties of the polymer matrix composite materials and possibilities through additive manufacturing (AM). [ABSTRACT FROM AUTHOR]

Delamination due to an inferior adhesion between reinforcement material and matrix in carbon fiber-reinforced thermoplastic (CFRTP) composites is a crucial problem to be solved. To this end, this study aims to overcome poor wettability between reinforcing phase, i.e., carbon fiber (CF), and thermoplastic matrix, i.e., polyetherether ketone (PEEK). Herein, CF's surface was tailored by application of different polymeric sizing agents which have different chemical structures. Morphology and topology analyses were performed by Scanning Electron Microscope and 3D laser scanning, respectively. Later, a variety of wettability results were obtained by the sessile drop method used in Contact Angle (CA) measurements for CFs throughout application of each sizing agent applied by dip coating. Sizing materials were designed such that the chemical structure of CF's surface could exhibit compatibility with the matrix itself. Consequently, complete wettability (CA: 0°) was achieved for CFs sized by HPEEK (CF/hydroxylated PEEK (HPEEK)) and the surface free energy (SFE) of CF was enhanced from 5.43 to 72.8 mJ/m2 while the SFE of the PEEK matrix is 40.1 mJ/m2. Moreover, sizing by HPEEK improved the average surface roughness of CF by 32% which enables optimized adhesion. Afterward, repetitive tensile tests were carried out to observe effects of improved interfacial interlocking on the mechanical properties of the final CFRTP composite. Stress–strain curves revealed that the tensile strength of CFRTP improved from 473 to 508 MPa through the sizing of CF by HPEEK whereas pristine PEEK has a much smaller tensile strength (98 MPa) than the aforementioned CF-reinforced composites. The sizing of carbon fiber's surface by HPEEK resulted in an enhanced adhesion with the PEEK matrix. Since the chemical structure and physical properties of sizing agent and matrix are compatible, potential debonding between them was eliminated. Thus, the improved wettability led to a substantial increase in the mechanical strength of the final TP composite. [ABSTRACT FROM AUTHOR]

The cracking of cementitious materials due to their quasi-brittle behavior is a major concern leading to a loss in strength and durability. To limit crack growth, researchers have incorporated microfibers in concrete mixes. The objective of this study is to determine if nano-reinforcements can arrest cracks and enhance the material performance in comparison to microfibers. A total of 28 specimens were prepared to investigate and compare the effects of incorporating carbon nanotubes (CNTs) as a nano-reinforcement and polyethylene (PE) fibers at a macro-level and their combination. Compressive and flexural strengths were experimentally tested to assess the mechanical performance. The microstructure of the mortar samples was also examined using a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The ductility increased by almost 50% upon the addition of CNTs, while no significant enhancement was witnessed for the compressive strength. The flexural strength increased by 169% and the flexural strain by 389% through the addition of the combination of CNTs and PE fibers. [ABSTRACT FROM AUTHOR]

In this work, mechanical properties of reinforced polypropylene composites were studied. PP in particulates shape with two different melt flow indexes (MFI) was used, i.e., 3 and 23 g/10 min, namely PP3 and PP23, respectively. Three different materials, namely TiO2 nanoparticle (nTiO2, spherical, 0D), micro-size short carbon fiber (SCF, fiber, 1D), and graphite nanoplatelet (GNP, sheet, 2D), were used as reinforcements/fillers. PP and fillers (in the desired composition) were first pre-mixed by a mechanical mixer. The mixture was then fed to a co-rotating twin-screw extruder for melt-compounding, followed by injection molding to fabricate testing samples. The microstructure and fracture surface of the composites were observed by a scanning electron microscope (SEM). Additionally, tensile, flexural, impact, and hardness tests were conducted to evaluate their mechanical properties. The SEM images stipulate that PP23 had better adhesion and dispersion with the fillers. The results from the SEM images support the mechanical testing results. PP23 composites exhibited more significant improvement in mechanical properties in comparison to PP3. At 5 wt. % filler loading, PP/GNP composite exhibited a greater improvement in mechanical properties compared with two other composites, which are PP/SCF and PP/nTiO2 composites for both PPs. [ABSTRACT FROM AUTHOR]

In this paper, four groups of graphene oxide and carbon fiber hybrid-reinforced resin matrix (GO-CF/EP) composites with different layering ways were prepared by a vacuum infiltration hot pressing system (VIHPS). The damping properties of the specimens with different layering ways were tested by the force hammer method, and the micromorphology of the specimens was photographed by scanning electron microscope. The experimental results showed that the damping properties of GO-CF/EP composites gradually increased with the increase in the number of Y-direction layers. The [XYXYXY]6 has the best damping property, with a damping ratio of 1.187%. The damping ratio is 5.3 times higher than that of [XXXXXX]6 layer mode, and the first-order natural frequency is 77.7 Hz. This is mainly because the stiffness of the X-direction layer is larger than that of the Y-direction layer, and its resistance to deformation is considerable. Therefore, its decay rate is slower. The Y-direction layer has weak resistance to deformation and fast energy attenuation. The increase in the number of Y-direction layers will lead to the overall increase in, and the improvement of, the damping properties of GO-CF/EP composites. [ABSTRACT FROM AUTHOR]

This article presents a self‐developed continuous fiber 3D printing device that incorporates a tilted printing axis. By positioning the print nozzle axis at an obtuse angle to the printing plane, the device effectively prevents the common issue of fiber damage during the 90° extrusion of continuous fibers. This improvement is substantiated through tensile strength experiments. Additionally, the pretreatment stage includes the twisting of continuous fibers to enhance friction along their length. This twisting process enables better retention of the matrix during impregnation, thereby improving impregnation performance. The cross‐section of the printed sample is observed by scanning electron microscope, and the microscopic effects of different process parameters on the continuous fiber structure are analyzed. Consequently, a link from process parameters to the mechanical properties of continuous fiber 3D printed specimens is established. This link serves as a foundation for predicting and optimizing the properties of continuous fiber‐reinforced materials. [ABSTRACT FROM AUTHOR]

The use of electrically conductive mortar (ECM) is a relatively new construction material technology developed to obtain high conductivity and mechanical strength. This study presents an experimental investigation on the heating performance and flexural strength properties of ECM mixed with carbon fiber (CF) and steel fiber (SF), which are conductive fibers. Furthermore, the internal microstructure of the ECM was analyzed with a scanning electron microscope (SEM) and thermogravimetric analysis was carried out using a thermogravimetric analyzer (TGA) device. The results of the experiment showed that the incorporation of SF had little effect on heating performance. In the case of CF, however, it was found that as the fiber contents and applied voltages increased, the heating performance increased. In particular, the maximum heating temperature of the ECM-CF125 specimen was 145.1 °C at an applied voltage of 30 V and an electrode spacing of 40 mm, which was about 7.3 times higher than the initial temperature (20 °C). In addition, the flexural strength of ECM mixed with SF was higher than that of plain mortar (PM), whereas the ECM-CF125 specimen showed a greater tendency to significantly decrease. It was confirmed that the hydration products and internal microstructures of the specimens were unaffected by repetitive electrical heating, and the ECM maintained stable electrical conductivity. [ABSTRACT FROM AUTHOR]

An experimental technique was developed for the production of tableted nanostructured fibrous enterosorbent for medical applications using a nanostructured activated carbon fiber material of solid-phase pyrolytic origin, created by our research team. The properties of the main active ingredient in the pills, as an effective adsorbing component, were studied. The porous structure parameters were examined with the desiccator method based on the absorption of benzene vapors, while the specific surface area was analyzed with the Brunauer–Emmett–Teller (BET) method. Spectrophotometric methods were employed to determine the concentration of the sorbate in solutions. The microstructure of the samples was studied using a scanning electron microscope (Superprobe-733 X-ray microanalyzer, JEOL, Japan). Energy-dispersive X-ray analysis provided data on the chemical composition and biocompatibility of the samples, serving as an integral indicator. Conditions for the key stages in the enterosorbent production process were experimentally tested. The influence of different types of binders on the process properties of the tablet charge and on the characteristics of test enterosorbent pills was analyzed. The novelty of the developed process was the use of material with special characteristics, promoted by bound carbon nanoforms present in its structure, for enterosorbent production. Improvements in the process operations were proposed, such as decreasing the compaction speed and simultaneously increasing the time the tablet charge was kept under pressure, leading to the redistribution of strains. It was proposed that the compaction process be conducted using punches with a flat surface of purity class 10 to prevent sticking. Therefore, our research team developed tableted enterosorbent with typical features of its main component—nanostructured activated fibrous carbon material—as an effective adsorbent for a relatively wide range of different compounds. [ABSTRACT FROM AUTHOR]

Removal of contaminants and top polymer layer from the surface of carbon-fiber-reinforced polymer (CFRP) composites is critical for high-quality adhesive-joining with direct bonding to the reinforcing fiber constituents. Surface treatment with a laser beam provides selective removal of the polymer matrix without damaging the fibers and increasing the wettability. However, inhomogeneous thermal properties of CFRP make control of laser ablation difficult as the laser energy absorbed by the carbon fibers is converted into heat and transmitted through the fiber structures during the laser operation. In this study, the effect of scanning speed and laser power on nanosecond laser surface treatment was characterized by scanning electron microscope images and wetting angle measurements. Low scanning speeds allowed laser energy to be conducted as thermal energy through the fibers, which resulted in less epoxy matrix removal and substantial thermal damage. Low laser power partially degraded the epoxy the surface while the high power damaged the carbon fibers. For the studied CFRP specimens consisting of unidirectional [45/0/−45/90]2s stacking of carbon/epoxy prepregs (HexPly®-M91), 100 mJ/mm2 generated by 10 m/s scanning speed and 30 W power appeared as optimum processing parameters for the complete removal of epoxy matrix from the top surface with mostly undamaged carbon fibers and super hydrophilic surface condition. Graphical Abstract [ABSTRACT FROM AUTHOR]

Currently, the mechanical performances of polylactic acid (PLA) samples prepared using the fused filament fabrication (FFF) technique are relatively poor. Hence, the carbon fiber (CF) is used to improve the thermal stability and mechanical property of FFF-ed PLA samples in this paper. The crystalline structure, thermal stability, melt flow rate, tensile strength and fractured surface morphology of PLA and PLA/CF samples were investigated with an X-ray diffraction device, differential scanning calorimeter, thermogravimetric analyzer, melt flow rate equipment, universal tensile test machine and scanning electron microscope, respectively. Meanwhile, the reinforcement mechanism of CF on the mechanical property of PLA samples was also analyzed. XRD results revealed that the diffraction peaks intensities of PLA/CF sample were obviously lower than those of PLA sample. TGA and DSC curves illustrated that the initial thermal decomposition temperature, thermal stability and crystallinity of the PLA/CF sample improved significantly. The tensile strength of the PLA/CF sample was 91.58 MPa, which was 42.49% higher than that of the PLA sample. Moreover, SEM images showed that the fractured behavior of the PLA sample varied from brittle fracture to ductile fracture after the introduction of CF. The results concluded the CF is a feasible fiber for enhancing the performances of the PLA sample. [ABSTRACT FROM AUTHOR]

To minimize structural heterogeneity during graphitization of polyacrylonitrile (PAN)‐based carbon fibers, the present authors prepare coaxial composite fibers with PAN as the skin and a PAN/MP mixture as the core by wet spinning with coaxial spinning needles. With increasing PAN mass fraction in the skin‐layer solution, the crystallinity of the coaxial composite fibers increases from 24.3% to 31.4%, and the crystal plane spacing of the coaxial composite fibers decreases from 0.529 to 0.523 nm. The tensile strength of the coaxial composite fibers increases by 122%, attributable to the crystallinity increase from 24.3% at 10 wt% PAN to 31.4% at 15 wt% PAN. Scanning electron microscope images of the coaxial fibers demonstrate that the cortical region changes from a porous, loose structure to a less porous, denser structure. Gray value testing of the coaxial composite fibers shows that transition layers formed at the interface between the cortex and core layers, which was formed for the outward diffusion of the core‐layer MP and PAN mixed solution. With increasing PAN mass fraction, because of the high viscosity of the cortical PAN solution, diffusion of the core‐layer mixed solution to the cortical layer decreases, resulting in a 75.2% increase in the core area ratio of the coaxial composite fibers. [ABSTRACT FROM AUTHOR]

Light-weight hybrid composites of relevant industrial applications were prepared using surface functionalized hierarchical carbon fibers (f -CF), silane treated hollow glass microspheres (HGM), and a blend of polypropylene (PP) and maleic anhydride-grafted-styrene ethylene butylene styrene as the base polymer matrix. The f -CF were prepared by coating amine functionalized carbon nanotubes onto silane treated CF using an ultrasonic assisted electrophoretic deposition technique to improve fiber-matrix interfacial adhesion. For hybrid composition of 20 wt.% f -CF and 10 wt.% HGM, the tensile strength and modulus improved by ∼141 and ∼536% over neat PP while flexural strength and modulus increased by ∼118% and ∼583% respectively. Impact strength of 11.06 kJ/m2 was obtained and uniform dispersion and distribution of f -CF and HGMs was observed in Scanning electron microscope (SEM) images. Desirable reduction in density and melt viscosity along with improvement in composite stiffness were observed due to addition of HGM filler. Compared to PP, the crystallization temperature increased by ∼12°C while a maximum decrease of ∼5°C in melting temperature was obtained for the hybrid composites. Crystallinity of the hybrid composites decreased with an evident β crystal formation brought in by the nucleation. [ABSTRACT FROM AUTHOR]

Still unsolved is the problem of monitoring the tissue regeneration with the use of implants (substrates) in in vivo conditions. The multitude of implant materials combined with their specific immanent often limit standard diagnostic methods, i.e. X-rey or computer tomography (CT). This is particularly difficult in therapies using polymeric high-resistance substrates for tissue engineering. The aim of this study was to fabricate a non-woven carbon fiber composed of carbon fibers (CF) which were then subjected to a surface modification by magnetron sputtering. A layer of iron (Fe) was applied under inert conditions (argon) for different time periods (2-10 min). It was shown that already after 2-4 minutes of iron sputtering, the voxel surface (CF_Fe2', CF_Fe4') was covered with a heterogeneous iron layer observed by scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDS). The longer the modification time, the more uniform the layer on the fiber surface becomes. This can be seen by the change in the wettability of the nonwoven surface which decreases from 131° for CF_Fe2 to 120° for CF_Fe10. The fibers do not change their geometry or dimensions (~11.5 um). The determination of pore size distribution by adsorption and desorption techniques (BJH) and specific surface area by nitrogen adsorption method (BET) have shown that the high specific surface area for the CF_Fe2' fibers decreases by 10% with the increasing iron sputtering time. All the studied CF_Fe fibers show good biocompatibility with osteoblastlike cells MG-63 cells after both 3 and 7 days of culture. Osteoblasts adhere to the fiber surface and show correct morphology. [ABSTRACT FROM AUTHOR]

The main objective of the work was to create a layer of carbon nanofibre on the surface of the NiTi shape memory alloy. The coating process was carried out in three stages. First, polyacrylonitrile was deposited by electrospinning. Then it was stabilized at temperatures up to 250°C. The last stage was the carbonization performed below 1000°C. The microstructure of the obtained coatings was observed using a scanning electron microscope. The X-ray diffraction techniques were applied to analyze the coating structure. After the polyacrylonitrile deposition, the fibers had an average diameter of about 280 nm, and the final fibers were almost twice as tiny. The applied steps also changed the phase and crystalline state of the fibers, finally leading to the formation of amorphous-nanocrystalline graphite. [ABSTRACT FROM AUTHOR]

Wood plastic composites are among the most popular engineering materials, used as deck materials as well as in construction. To improve the properties of wood plastic composites, they are reinforced with various materials. This study investigates the synergic effect of glass fiber and carbon fiber reinforcement on wood plastic composites regarding their physical, mechanical, and fire resistance performance. The reinforcement materials significantly limited the water absorption due to their hydrophobic nature. The reinforcement fibers acted as a barrier against water and limited the uptake although the water absorption and thickness swelling values increased with exposure time. Moreover, the high strength of the reinforcement fibers improved the modulus of elasticity up to 122% and 41% for the flexural strength. Additionally, the long glass fibers significantly contributed to improving the tensile strength, which indicates that fiber length is essential. The scanning electron microscope micrographs revealed that the carbon fibers had a rougher surface than the glass fibers, proving their higher resistance to stress. The observed gaps were also evidence of poor adhesion between the matrix and the fibers. On the other hand, the carbon fibers and long glass fibers positively affected the load transfer in the matrix. Unfortunately, the fiber reinforcement has only a slight effect on the fire resistance performance. Furthermore, the improvement in the limit oxygen index test values was limited. However, the reinforcement fibers exhibit a barrier effect, inhibiting dropping, which is crucial for structural integrity. [ABSTRACT FROM AUTHOR]

In order to investigate the effects of different functional groups on graphene on the mechanical behavior of carbon fiber reinforced epoxy composites were fabricated by hand layup technique. In this study, three different variety of functionalized graphene (–NH2, –COOH, and –OH) with varying weight percent (i.e. 0.1, 0.3, and 0.5 wt%) was considered. Tensile, interlaminar, and three-point flexural tests were conducted to evaluate the effects of graphene concentration and fiber stacking sequence (i.e. 0/90° and 0/90/ ± 45°) on composites. The microstructures of the composites were characterized by a scanning electron microscope. Experimental results showed that pristine and functionalized graphene significantly improved the mechanical properties of carbon fiber epoxy composites. Compared to neat carbon fiber epoxy composites, the maximum tensile strength of 33.34% and 26.35% were noticed for 0/90°–COOH–0.5 and 0/90/ ± 45°–NH2–0.3 stacked functionalized graphene modified carbon fiber epoxy composites, respectively. Moreover, 48.44% and 59.1% flexural strength were recorded for 0/90°–COOH–0.3 and 0/90/ ± 45°–OH–0.5 stacked functionalized graphene modified carbon fiber epoxy composites, respectively. Furthermore, maximum interlaminar shear strength (ILSS) of 120.25% was observed for 0/90/ ± 45° stacked carbon fiber epoxy composites. Finally, the results obtained with graphene as reinforcement filler can cause a significant improvement in the mechanical performance of fiber composites. Henceforth, they can also be considered as a promising candidate for designing composites for structural applications. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polymers and their composites have undergone massive development over the years through intensive research studies. The plethora of opportunities offered by these materials is greatly complimented by the advent of additive manufacturing. The present work analyses the mechanical properties of glycol‐modified polyethylene glycol (PETG) reinforced with organically modified montmorillonite (OMMT) nanoclay and short carbon fibers (SCF). This work is the first of its kind to offer a complete overview of the mechanical properties of the composites prepared by these materials through 3D printing without the application of any post‐processing techniques. These materials are initially compounded and followed by extrusion using a single‐screw extruder to obtain fine filaments of 1.75 mm diameter. The specimens of PETG composite filaments were 3D printed as per the ASTM standards, using fused deposition modeling technique without any post‐processing. The fabricated PETG/OMMT/SCF specimens are tested to study its tensile, compression, flexural, impact, and hardness properties. The fractured specimens from the tensile tests are analyzed using a scanning electron microscope. It is seen that the addition of OMMT nanoclay improves the properties of the composites by a significant extent for most of the tests. However, the addition of SCF has a negligible effect on the properties of the composites due to the presence of interstitial voids and poor matrix‐fiber bonding. This calls for additional process parameter variations and post‐processing techniques like pre‐stressing, annealing, and others. These composites can be used in a wide variety of applications ranging from secondary structures in aerospace, automotive applications to minor orthotic and prosthetic applications. [ABSTRACT FROM AUTHOR]

Thin-walled coilable composite shells have been successfully used in deployable space payloads due to their high storage efficiency and stiffness-to-weight ratio. However, in real-life applications the deployable composite shells requiring repeatable coiling up and deployment are easy to be damaged, and their damage or failure behaviors due to large deformations has been rarely studied. This paper aims to investigate their damage and failure behaviors during the snap through, equal-sense and opposite-sense coiling up. First, multiscale models are established to compute the mechanical properties of plain-woven fabrics and unidirectional prepregs with consideration of stiffness reduction of the composites. Then, damages of each ply within the thin-walled shell are studied during snap through and coiling up. Simultaneously, effects of hub diameter on the damage of the thin-walled shell were investigated, followed by experimental verification using strain gauges and a scanning electron microscope (SEM). Simulation and experimental results show that the dominated damage of the thin-walled shell is failure of matrix. The SEMs of the edge damaged show failures of both resin and carbon fibers. Tensile damages of matrix can be relieved as the increment of the hub diameter, and no obvious failure is observed at the hub diameter of 50 mm. [Display omitted] • Multi-scale models with consideration of stiffness reduction are set up. • Damages of deployable composite shells during coiling up are analyzed. • Effect of hub diameter on the damages of composite shells is investigated. • Strains of the shell are experimentally measured to validate simulation results. • Edge damage during equal-sense coiling up is investigated via SEM. [ABSTRACT FROM AUTHOR]

The properties of carbon fiber (CF) reinforced thermoplastic resin composites depend on the physical and chemical interaction between the fibers and the resins. However, surface oxidation is not always necessary. In this study, the interaction between CF and Polyphenylene sulfide (PPS) is enhanced by using an emulsion of reactive sulfur to treat the CF surface. The interlaminar shear strength (ILSS) of CF/PPS composites is experimentally investigated and found to be up to 79.7 MPa, an increase of 36.1% compared to the untreated CF. The enhancement mechanism of the modification method established is inferred. Scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS) results showed that sulfur etching on the surface of CF generated new functional groups, which improved the interfacial effect, and tightened the bond between CF and PPS. This indicates that sulfur treatment along with sizing must be a simpler method than surface oxidation to promote the interfacial bonding between CF and PPS. [ABSTRACT FROM AUTHOR]

This article investigates the effect of geometrical alternatives for fiber directions on the structural and tribological properties of glass and carbon fibers when molded with epoxy as polymeric composite fabrics for the safety and quality of bushing applications. To confirm the best composite fabric direction, scanning electron microscope and tribological analyses were carried out for the glass and carbon fabrics at horizontal and vertical geometrical alternative orientations. The tribological test was applied using a pin-on-disk tribometer at constant bark velocity of 0.520 m/s against different loads, beginning with 5, 10, 15, and 20 N for the investigated composite samples. The structural measurements demonstrated that the carbon fiber had a high ability to merge with the resin epoxy when compared with the glass fiber. The tribological analysis elucidated that the lower wear volume loss and friction coefficient were obtained when molding the resin epoxy horizontally to the fiber-stacking direction compared with the other vertical direction. Accordingly, the study deduced that the carbon fiber composite material achieves superior wear resistance when molded by resin epoxy horizontally to the direction of tribological wear, which is suitable for several advanced bushing applications. [ABSTRACT FROM AUTHOR]

This study evaluated the Mode I interlaminar delamination fracture toughness of s-CF/PA6 (short Carbon Fiber/Polyamide 6) laminates molded by FDM (Fused Deposition Molding) type 3D printer, using DCB (Double Cantilever Beam) tests on two different configurations. We also tested and compared dried and undried specimens. Fracture surface observations by scanning electron microscope revealed the mechanism of toughness development and factors affecting interlaminar delamination fracture toughness. The results showed that angle ply exhibit higher toughness than cross ply. The toughness of dried specimens was higher than that of the non-dried specimens. These results were highly variable. One reason for this is the difference in adhesion states and voids between layers. One possible cause of insufficient welding is a molding area temperature during molding. In addition, insufficient welding may occur if the filaments are printed when they are not sufficiently dry. As for voids, there is a possibility that they can be improved by adjusting the 3D printer. [ABSTRACT FROM AUTHOR]

Molybdenum disulphide (MoS2), conversion-type transition metal dichalcogenide, despite having the high theoretical capacity and adequate stability, suffers from poor electronic conductivity; large volumetric changes leading to material degradation and agglomeration of nanostructures after long cycling are hindering its practical application. This work presents the tactics used to mitigate the hindrances by doping the MoS2 matrix with phosphorus (P) and is grown directly on carbon cloth without any binders via a simple one-step hydrothermal method. A mechanism of crystal structure transformation with respect to the doping concentration is proposed based on X-ray diffraction and ultraviolet–visible spectrum results. Raman analysis is carried out to conclude the phase examination of MoS2. The reduction in agglomeration of MoS2 nanoparticles due to the P doping is analysed by employing scanning electron microscope. The optimized P-MoS2 is used directly as an anode in Lithium-ion batteries which exhibits high initial discharge capacity (2032 mAhg−1 at the 40th cycle with a current rate of 100 mAg−1) and reasonably good stability (713 mAhg−1 after 500 cycles at 500 mAg−1). Compared to that of bare MoS2 electrode, the better performance of P-MoS2 anode is due to the synergetic effects of optimized P doping and the presence of P–O bonds. [ABSTRACT FROM AUTHOR]

Various methods for preparing fibrous materials [substrates in which polymer filaments of various nature are decorated with particles and/or layers of metallic silver (Ag)] are compared and analyzed. Ion-plasma magnetron sputtering is shown to be the most promising method for modifying materials made of polypropylene and fluoroplastic fibers with Ag. Reductive adsorption is the most effective method for surface modification of carbon fibers with Ag. Photographs taken on a scanning electron microscope that characterize the morphology of Ag-containing fibers are presented. The bactericidal activity of Ag-containing fibers of various types is demonstrated. Hypotheses explaining the high antimicrobial activity of Ag-modified carbon fibers are proposed. [ABSTRACT FROM AUTHOR]

CF/PEEK composites were prepared by vacuum hot pressing sintering technology. The thermal properties of the materials were tested by thermal conductivity analyzer and TG tester. Multifunctional friction and wear testing machine, 3D morphology profilometer, scanning electron microscope and friction electrometer were used to analyze the friction and wear properties and anti-friction electrostatic properties of the materials. The results show that with the increase of the forming temperature, the friction coefficient and wear rate of the materials decrease gradually. With the increase of CF contents, the friction coefficient, wear rate and friction electrostatic voltage decrease first and then increase. When the CF content is as 20%, the friction coefficient, wear rate and friction electrostatic voltage reach the lowest values, which are as 0.247, 5.6 x 106 mm/(N ⋅ m) and 3.3 V, respectively. Friction and electrostatic data show that the CF/PEEK materials prepared by this method have better friction properties and anti-electrostatic properties than that of commercial composites. The wear mechanism of CF/PEEK composites is mainly adhesive wear, accompanied by slight abrasive wear. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current research article assesses the feasibility of recycled CFRP (Carbon‐Fiber‐ Reinforced‐Polymer) fibers in high‐strength concrete. Different dosages of recycled CFRP fibers (0.2%, 0.4%, 0.6%, 0.8%, and 1%) as well as different aspect ratios of CFRP fibers with 10 and 20 mm fiber lengths is assessed for hardened state characteristics of reinforced high‐strength concrete. Furthermore, ultrasonic pulse velocity test, compression test, flexure test, and impact resistance test are performed to understand the hardened properties of specimens. The chemical composition of various elements present in the various kinds of concrete samples is qualitatively and quantitatively found with the help of energy‐dispersive X‐ray spectroscopy (EDX) equipment. To understand the surface morphology of carbon fibers incorporated in concrete samples, Scanning electron microscope (SEM) photographs are obtained to examine the prepared samples thoroughly. Linear regression analysis, an analytical analysis technique, is incorporated to linearly correlate the different hardened mechanical characteristics of specimens taking into account varying lengths and different dosages of recycled CFRP fiber. The findings reveal that increasing the CFRP fiber dosage and the aspect ratio of recycled CFRP fiber improves the reinforced mix composition's mechanical characteristics. [ABSTRACT FROM AUTHOR]

• The project presents an application of FCN in characterizing CF distribution in CFRC. • The FCN-based method computes the CF distribution based on its real distribution. • The relationship between CF distribution and CFCR properties is analyzed. • The continuous evaluation method is reasonable for the CF distribution evaluation. Scanning electron microscope (SEM) is proven effective to analyze the morphology of carbon fibers (CFs) presenting in CFRC. However, the qualitative observation has limited contribution to the improvement of CF distribution as well as the properties of CFRC. In this work, a fully convolutional network (FCN) was developed to segment CFs from SEM images for quantitative CF distribution characterization. Three processes involved in the establishment of the FCN and its application for the CF distribution evaluation, which were: (a) generating a database including 560 CFRC SEM images in different scales; (b) designing, training, and testing an encoder-decoder network and other layers for the FCN; and (c) evaluating the CF distribution and analyzing the relationship between the CF distribution and the CFRC properties using segmentation results. The results showed that the FCN provided reasonable segmentation results for CF clusters with the 0.94F-Measure, 0.92 recall, and 0.96 precision, respectively. The FCN had stable segmentation results under different SEM magnifications. The FCN-based method was proven effective to segment CF clusters in real time, which met the demand for continuous SEM observation. The continuous observation results indicated that the mechanical and electric properties of CFRC were improved by the improvement of the CF distribution. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) laminates have been widely employed in the manufacturing of airplane. Usually, hole-making is the final machining process to join CFRP laminates with other components. However, CFRP laminates are considered as hard-to-machine materials, which results in some serious failures during hole-making process such as fiber pull-out, fiber break, and matrix delamination. To improve the hole-making quality, a tilted orbital grinding (TOG) method was proposed in this study. In the proposed TOG method, a grinding wheel was used as the machining tool and its axis was set as tilted against the axis of the hole with a small angle. Through replacing the revolving motion of the tool in conventional helical milling with conical pendulum motion of the grinding wheel, a hole could be made by a grinding process. The thrust forces, cutting temperatures, and the quality of the holes in the proposed TOG process were investigated by experimental methods. The results show that the thrust forces and cutting temperatures in TOG process are greatly less than those in the conventional orbital milling process. Scanning electron microscope (SEM) images of the hole that made by TOG method show that there is no crack generated in the entrance side of the hole, and the pull-out delamination in the exit side of the hole is significantly reduced. The experimental results indicate that the proposed TOG method has a potential application in the hole-making of CFRP laminates. [ABSTRACT FROM AUTHOR]

Carbon-based materials have been attaining a great interest from researchers due to its versatility. This study intended to assess the potential of carbon fibre and its composite for bone replacement. The morphological, electrical conductivity and nanomechanical properties (modulus and adhesion energy) of locally obtained carbon fibre were assessed via microscopic devices of scanning electron microscope (SEM) and an atomic force microscopy (AFM), respectively. The carbon fibre was compounded with polyamide 6 and injection moulded prior to assessment of its tensile and morphological properties. The electrical conductivity of the carbon fibre was in a range of 0–1 mA. Whereas the mean modulus and adhesion energy were 1.96 GPa and 22.97 fJ, respectively. The tensile strength and modulus of the composite increased by 14.7% and 13.7% as compared to unfilled polyamide 6. With potential cells stimulating capability owing to its electrically conductive and excellent mechanical properties, carbon fibre could be hypothetically used with selected matrix for replacement of bone in non-load bearing areas such as craniofacial part. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastic (CFRP) is extensively used in automotive and aerospace industries with the aim to achieve reduction on emissions by reducing weight. Due to governmental regulations to reduce the environmental impact and to reduce waste, the need for remanufacturing CFRP is becoming an interesting area of application with economic benefits to industry. This is important as manufacturing carbon fiber is a costly process and remanufacturing CFRP is more cost effective and reduces the dependency on virgin materials. Processing CFRP to meet demands, for fast and high-quality cuts, can impose problems for conventional methods. The use of multi-pass scanning technique in laser cutting CFRP is investigated using a 1.5 kW fiber laser with assist gas pressure of 16 bar and gas flow rate of 126 lt/min. Using multi-pass technique, a through cut can be obtained by repeating the beam travel more than once. The advantage of laser cutting when compared with traditional CNC, is the low cost of maintenance over time due to the non-contact nature of the process i.e. no wear of tool at contact area. And due to the small beam spot size of the laser small and complex shapes can be cut. The aim of the paper is to determine how the process performs in terms of cutting speed and fiber damage. Average power was used to carried out experimental tests. A fiber damage below 100 µm with laser cutting speed of 2.5 m/min and above was obtained. Thermal effects were analyzed using scanning electron microscope (SEM) and optical microscope (OM). The fiber damage was further optimized using specialist methods such as double aperture nozzle and trenching. The use of trenching and double aperture further reduces the fiber damage to 10 µm and 50 µm, respectively with laser cutting speed of 7.5 m/min and 3.33 m/min. [ABSTRACT FROM AUTHOR]

In this study, poly (ether ether ketone) (PEEK)/polytetrafluoroethylene (PTFE) composites reinforced with carbon fibers (CFs) and graphite (Gr) were fabricated by compressive molding technology. The friction and wear properties of the PEEK/PTFE composites sliding against Si3N4 balls were investigated using ball-on-disk configuration under dry sliding conditions, and the morphologies of the worn surfaces were also observed with a scanning electron microscope (SEM) and a three-dimensional morphometer. The results indicated that the introduction of CFs significantly improved the tribological properties of the composites, but the friction coefficient of the PEEK/PTFE/CFs composites were higher than the pure PEEK/PTFE composites. However, it was found that a combinative addition of CFs and Gr creates an obvious synergetic effect of improving the friction-reducing and anti-wear abilities of the composites. The mechanisms of the improved tribological properties of the PEEK/PTFE/CFs/Gr composites were discussed based on the analysis of the worn surfaces and tribofilms. [ABSTRACT FROM AUTHOR]

In this work, the effect of a hydrothermal environment on mechanical properties and the electrical response behavior of continuous carbon fiber/epoxy (CFRE) composite produced by the pultrusion method were investigated. Due to the relatively uniform distribution of fibers and lack of resin-rich interlayer area, this effect for the pultruded CFRE composite plates is different from the common CFRE laminated composites. Firstly, its hygroscopicity behavior was studied. The absorption ratio increases rapidly to 1.02% within 3 days before reaching a relatively stable state. A three-point bending test, a Vickers hardness test, a thermogravimetric analysis (TGA), and a scanning electron microscope (SEM) analysis were performed to investigate the effect of the hydrothermal environment on the mechanical properties and thermal stability of the CFRE composite. The results indicated that the bending strength decreased quickly within 3 days of hydrothermal treatment, followed by a stable trend, which coincided with that of the hygroscopicity behavior of the composites. The fracture surface analysis indicated that the interfacial properties of carbon fibers in the epoxy matrix were decreased after the hydrothermal treatment, and more carbon fibers could be pulled out from the CFRE in the hygroscopic state. After the hydrothermal treatment, the micro-hardness of the composites was reduced by 25%. TGA confirmed the decreased thermal stability of the CFRE composites after the hydrothermal treatment as well. Moreover, the hydrothermally treated CFRE composites could a reach stable resistance response more readily. The revealing of the effect of moisture and hot environment on the mechanical properties and electrical response behavior of pultruded CFRE composites prepares the ground for their design and practical application in the corresponding environment. [ABSTRACT FROM AUTHOR]

Active carbon fibers (ACFs) with a large specific surface area (SSA) have received widespread attention in various fields, such as environmental treatment and energy storage. Herein, ultrafine viscose‐based active carbon fibers (UVACFs) with large SSAs and micropores are successfully prepared via stabilization, carbonization, and CO2 activation using ultrafine viscose fibers (UVFs) as precursors. The microporous structure and SSA of UVACFs are adjusted by the activation temperature and the morphology and structure are characterized by a scanning electron microscope, X‐ray diffraction, Raman spectroscopy, and N2 adsorption/desorption. As a result, the SSA of UVACFs can reach 591.58 m2 g−1 with the main pore size of 0.52 nm under activation temperature of 900 °C. The adsorption capacity of UVACFs‐900 for iodide ions is as high as 830.3 mg g−1, which is the highest one among reported ACFs. It is attributed to the fact that the pore size of as‐prepared UVACFs is close to the hydration radius of iodide ions (0.335 nm). Moreover, NiCo2O4 is grown uniformly on UVACFs by the hydrothermal method, which shows high capacitance of 2693.3 F g−1 at 1 A g−1 and excellent cycling stability with 94.5% capacity retention after 3000 cycles (10 A g−1). [ABSTRACT FROM AUTHOR]

High‐performance fibers such as carbon, aramid, and glass fiber generally have excellent mechanical, thermal, and chemical resistance and they have potential applications in oil and gas exploitation where high‐temperature and high‐pressure (HTHP) H2S/CO2 corrosive environments usually exist. To investigate the corrosion behavior of these fibers under such environments, two corrosion environments (HTHP water, HTHP H2S/CO2) were simulated in a high‐temperature high‐pressure reactor. Scanning electron microscope, X‐ray diffraction, density measurements, and single fiber tensile test were performed to study the surface morphology, crystal structure, and mechanical properties before and after corrosion. After exposure to the second corrosion environment, the carbon aramid fibers had no obvious mass loss and tensile strength retention of 70.28% and 49.66%, respectively. The surface of the aramid fiber and carbon fibers was significantly damaged which led to an increase in surface defects and a decrease in crystallinity. The glass fiber had clear weight loss due to a large number of defects being formed in the structure and the retention of tensile fracture strength was 48.18%. Corrosion under HTHP H2S/CO2 conditions caused more serious damage to the high‐performance fiber structures. [ABSTRACT FROM AUTHOR]

Delamination is always considered as a threat to the resin matrix composite laminates due to the nonvisibility from the outside. Much effort on the interleaving toughening has been made to improve the interlaminar fracture toughness. The synergistic toughening effect of thermoplastic resin and carbon nanotubes (CNTs) has been the topic in the interleaving toughening. In this study, the influence of the hybrid structure between thermoplastic polyetherketone‐cardo (PEK‐C) and CNTs on the toughening efficiency was investigated. The mode II interlaminar fracture toughness was tested and the fracture surface was examined by scanning electron microscope. The results showed that the interlaminar structure was closely related with the interlayer structure and the synergistic toughening effect depended greatly on the hybrid structure. [ABSTRACT FROM AUTHOR]

The ultrasonic welding (UW) technique is a fast-joining process; it is very suitable for the carbon fiber reinforced thermoplastic (CFRTP) composite. For improving the consistency of the welded joint quality, a new pre-pressing ring clamp (PPRC) was designed for ultrasonic welding carbon fiber reinforced nylon composites in this paper. The effects of the PPRC on the weld quality of the ultrasonic welding welded 4.0 mm thick 30% mass short carbon fiber reinforced Nylon 6 composite was investigated and compared with that of normal clamp weld joint. The weld strength, microstructure, and temperature evolution of the joint were analyzed by tensile test, scanning electron microscope, and temperature measurement. The results showed that the PPCR UW joints had larger central weld nugget size (478 mm2 vs. 300 mm2), thicker stable fusion region thickness (1.10 mm vs. 0.96 mm), resulting in a higher joint strength (6.86 kN vs. 6.21 kN) compared with the normal clamp UW joints under the same welding parameters. The real-time monitor curve of the horn displacement and temperature at the faying interface showed that the PPRC increased the heat rating at the faying interface during instable melting stage. The PPRC could improve the contact condition between workpieces and the utilization efficiency of ultrasonic energy, which boosted the melting rate of materials at faying interface and consequently the formation of a sound joint with enough weld size (i.e., 433 mm2) in a shorter welding time (i.e., 1.3 s). Therefore, the flexibility of component assembly would be increased by the use of this sort of clamps. [ABSTRACT FROM AUTHOR]

An investigative work was conducted to examine the tensile, flexural and impact strength of carbon fiber reinforced vinyl ester composites filled with different proportions (0, 0.5, 1, 1.5 and 2) of graphitic carbon nitride (g-C3N4) and silicon nitride (Si3N4) filler. Composites were fabricated by hand layup method. Results showed an increase in tensile strength of g-C3N4 and Si3N4 particles content by 1% and beyond which the strength decreased. With the addition of 1wt% of g-C3N4 and Si3N4 in carbon fiber reinforced vinyl ester composites, the flexural strength increased to 16% and the tensile strength increased by 10%. The eroded surface of specimen was observed under scanning electron microscope and the results are reported. Incorporation of nano fillers in hybrid polymer composite will enhance the mechanical properties. Hence hybrid C-V extensively used in marine applications. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyurethane cement (PUC) is now commonly used in the reinforcement of old bridges, which exhibit various issues such as poor toughness, temperature-sensitive mechanical properties, and brittle failure. These problems can lead to the failure of the reinforcement effect of the PUC on old bridges in certain operating environments, leading to the collapse of such reinforced bridges. In order to alleviate these shortcomings, in this study, the toughness of PUC is improved by adding polyvinyl alcohol (PVA) fiber, carbon fiber, and steel fiber. In addition, we study the change law of the flexural strength of PUC between −40 °C and +40 °C. The control parameters evaluated are fiber type, fiber volume ratio, and temperature. A series of flexural tests and scanning electron microscope (SEM) test results show that the flexural strength first increases and then decreases with the increase in the volume-doping ratio of the three fibers. The optimum volume-mixing ratios of polyvinyl alcohol (PVA) fiber, carbon fiber, and steel fiber are 0.3%, 0.04% and 1%, respectively. Excessive addition of fiber will affect the operability and will adversely affect the mechanical properties. The flexural strength of both fiber-reinforced and control samples decreases with increasing temperature. Using the flexural test results, a two-factor (fiber content, temperature) BP neural network flexural strength prediction model is established. It is verified that the model is effective and accurate, and the experimental value and the predicted value are in good agreement. [ABSTRACT FROM AUTHOR]

Although carbon fibers (CFs) are born with special physicochemical properties, the common CFs show the poor adsorption performance owing to the lack of adsorption sites and porosity with low specific surface area. As emerging functional materials, metal‐organic frameworks (MOFs) have attracted significant attention due to excellent properties, which has the ability of remedying drawbacks of other materials. In this study, zeolitic imidazolate framework‐8 (ZIF‐8) was rapidly coated on the surface of carbon fibers (CFs) (CF/ZIF‐8) via in‐situ self‐assembly approach in 10 min. The scanning electron microscope (SEM) images show ZIF‐8 film on CF is dense and homogeneous due to the low reactivity of zinc acetate and the coordination interaction between Zn2+ and carboxyl of CF treated by nitric acid (CF‐COOH). The Brunauer‐Emmett‐Teller (BET) surface area of CF/ZIF‐8 composite is about 30 times larger than that of pristine CF. The adsorption selectivity of CFs was increased after the modification of ZIF‐8 demonstrating by adsorbing different dyes. The CF/ZIF‐8 composites were applied to remove congo red (CR) from aqueous solutions with the adsorption capacity 40 times more than that of pristine CF and CF‐COOH, because of the increasing specific surface, electrostatic interaction and π‐π interaction between ZIF‐8 and CR molecule. The MOFs/CFs composites we fabricated also have great promise applications in micro‐preconcentration and electrochemistry. [ABSTRACT FROM AUTHOR]

A longitudinal compression test for a single polyacrylonitrile-based carbon fiber (T300) was performed using a scanning electron microscope. The compressive stress/strain behavior was initially linear, but subsequently became nonlinear. The longitudinal tangent modulus decreased with increasing compressive strain. A cyclic compression test revealed that the T300 carbon fiber deformed elastically up to ~90% compressive strength. The variability in the compressive strength was evaluated using Weibull analysis. The representative compressive strength of the T300 carbon fiber was nearly the same as the tensile strength. The compressive strength of the T300 carbon fiber was almost same as that of the high-tensile strength T800S carbon fiber. Finite element analysis was performed to investigate the validity of the test method. The results showed that the longitudinal compressive stress on the carbon fiber varied during longitudinal compressive loading. The maximum longitudinal compressive stress in the carbon fiber was slightly higher than the average compressive strength applied at the end. However, the variability in the measured compressive strength was much higher than that in the longitudinal compressive stress on the carbon fiber, which does not affect the former. [ABSTRACT FROM AUTHOR]

Abstract: We report a novel material testing system (MTS) that uses hierarchical designs for in-situ mechanical characterization of multiscale materials. This MTS is adaptable for use in optical microscopes (OMs) and scanning electron microscopes (SEMs). The system consists of a microscale material testing module (m-MTM) and a nanoscale material testing module (n-MTM). The MTS can measure mechanical properties of materials with characteristic lengths ranging from millimeters to tens of nanometers, while load capacity can vary from several hundred micronewtons to several nanonewtons. The m-MTM is integrated using piezoelectric motors and piezoelectric stacks/tubes to form coarse and fine testing modules, with specimen length from millimeters to several micrometers, and displacement distances of 12 mm with 0.2 μm resolution for coarse level and 8 μm with 1 nm resolution for fine level. The n-MTM is fabricated using microelectromechanical system technology to form active and passive components and realizes material testing for specimen lengths ranging from several hundred micrometers to tens of nanometers. The system's capabilities are demonstrated by in-situ OM and SEM testing of the system's performance and mechanical properties measurements of carbon fibers and metallic microwires. In-situ multiscale deformation tests of Bacillus subtilis filaments are also presented. [ABSTRACT FROM AUTHOR]

Polymerase chain reaction has gained attention since the outbreak of novel coronavirus in 2019. Due to its high specificity and capability for early detection, it is considered a standard method for the diagnosis of infectious diseases. However, the conventional thermocyclers used for nucleic acid amplification are not suitable for point-of-care testing applications, as they require expensive instruments, high-power consumption, and a long turnaround time. To suppress the widespread of the pandemic, there is an urgent need for the development of a rapid, inexpensive, and portable thermal cycler. Therefore, in this paper, we present a conductive silver/carbon fiber film-based thermal cycler with low power consumption (<5 W), efficient heating (~4.5 °C/s), low cost (