Carbon Nanofiber Reinforced Research Articles

Recycled Carbon Nanofiber-Polypropylene Nanocomposite: A Step towards Sustainable Structural Material Development

Plastic products play a significant role in fulfilling daily necessities, but the non-decomposable nature of plastic leads to inescapable environmental damage. Recycling plastic material is the most appropriate solution to avoid pollution and short product lifespan. The present study shows the recycling effect on carbon nanofiber (CNF) reinforced polypropylene (PP) nanocomposite to attain the purpose of reuse and sustainability. 30 wt% CNF melt-blended with polymer and PP-nanocomposites were fabricated using the injection molding technique. PP-CNF nanocomposites were recycled, and mechanical, thermal, and morphological properties were investigated. Three-point bending and tensile testing showed a low decrement of ~1% and ~5% in bending and tensile strength after recycling 30 wt% PP-CNF nanocomposites. Scanning electron microscopy (SEM) images show that the alignment of CNF was disturbed after recycling due to the decrement in the aspect ratio of CNF. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) showed that the crystallinity of PP increases with recycling. The lowering of interfacial interaction between CNF and PP after recycling was studied by a stress-controlled rheometer. The decrement in mechanical properties of PP-CNF nanocomposite is not significant due to CNF reinforcement; hence, it can be reused for the same or other structural applications.

Mechanical and Microstructural Characterization of Carbon Nanofiber–Reinforced Geopolymer Nanocomposite Based on Lunar Regolith Simulant

AbstractUsing the Moon’s natural resources to build infrastructure is the first step toward lunar colonization. Lunar regolith, rich in aluminosilicate, has the potential to prepare geopolymer for ...

Investigation of machinability properties of aluminium matrix hybrid composites

In this study, machinability properties of aluminium matrix boron carbide (B 4 C) and carbon nanofiber (CNF) reinforced hybrid composite material produced by powder metallurgy in drilling were investigated. In the study, the samples produced with hot pressing technique having 6 different volume rates were used. The drilling operations were performed using drills with 3 point angles (90°–118°–135°) at 30–45-67.5 m/min cutting speed and 0.1–0.15–0.225 mm/rev feed rate. As a result of the experiments, the thrust force, moment, and surface roughness were measured and the delamination factor forming at hole exits was calculated. In addition, the effect of reinforcement rate on the machinability was also investigated. In all drill types, it was determined that as the feed rate increased, the thrust force increased and as the reinforcement rate increased, moment values also increased. Surface roughness values increased with the increased feed rate but decreased as the cutting speed increased. As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased. • Low volume rate carbon nanofiber reinforcement had a positive effect on machinability properties. • As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased. • Surface roughness decreased with the increase in the amount of reinforcement. • The two most effective parameters in hole exit damage are the point angle and feed rate.

Research on the Mechanical Performance of Carbon Nanofiber Reinforced Concrete under Impact Load Based on Fractal Theory

The research is focused on the dynamic compressive strength, impact toughness and the distribution law of fragmentation size for the plain concrete and the carbon nanofiber reinforced concrete with four fiber volume contents (0.1%, 0.2%, 0.3% and 0.5%) under impact load by using the Φ100 mm split-Hopkinson pressure bar. Based on the fractal theory and considering the micropore structure characteristics of the specimen, the impact of the strain rate and the dosage of carbon nanofibers on the dynamic mechanical performance of concrete is analyzed. According to the results, both the dynamic compressive strength and the impact toughness increase continuously with the improvement of the strain rate level at the same dosage of fiber, showing strong strain rate strengthening effect; at the same strain rate level, the impact toughness increases gradually with the increase in the fiber dosage, while the dynamic compressive strength tends to increase at first and then decrease; the distribution of the fragmentation size of concrete is a fractal in statistical sense, in general, the higher the strain rate level, the higher the number of fragments, the lower the size, and the larger the fractal dimension; the optimal dosage of carbon nanofibers to improve the dynamic compressive strength of concrete is 0.3%, and the pore structure characteristics of carbon nanofiber reinforced concrete exhibit obvious fractal features.

Influence of carbon nanofiber reinforcement on mechanical properties of polymer composites developed by FDM

Polymers are new class of materials that have seen its utilization in every aspect of daily routine. Implementation of polymers in mechanical and functional parts of the machinery of automotive and aerospace needs to be improvised with improvement in mechanical properties of pure polymers. In the present investigation carbon nanofibre reinforced ABS based polymer composites were developed by FDM process. Compounding and twin screw extrusion technique was employed to develop filament used for FDM process. 2 wt% carbon nanofibre was added to ABS plastic pallet percentage of carbon nanofibres was varied from 0 to 2 wt% in steps of 1 wt% carbon nanofibres filled FDM parts were subjected to Tensile test, Dimensional accuracy, and surface roughness test. Addition of carbon nanofibre contained the mechanical properties of FDM parts.

Polypropylene nanocomposites with high-loading conductive carbon nano-reinforcements for multifunctional applications

Lightweight automotive parts fabrication is an essential criterion for the improvement of the efficiency of vehicles. In this work, different weight (wt) content of commercially developed carbon nanofiber (CNF) and granulated graphitized graphene (GRP) were melt extruded with polypropylene (PP) with the aim of improvement in mechanical and electrical properties. The CNF–PP and GRP–PP nanocomposites were developed by injection molding technique, and mechanical as well as electrical properties at different reinforcement content were studied. A three-point bending test showed that flexural strength and modulus increases with increment in nanofiller content, and maximum mechanical properties were obtained by 45 wt% CNF–PP and 60 wt% GRP–PP nanocomposites. Electrical conductivity of 1.4 and 0.4 S/cm were achieved by incorporating 60 wt% CNF and 60 wt% GRP in PP nanocomposites. Thermal stability was studied by thermogravimetric analysis (TGA), and maximum thermal stability was achieved by 45% CNF–PP nanocomposites. Morphological study by scanning electron microscopy (SEM) showed considerable aligned CNF selectively located in the PP matrix and exhibited oriented dispersion while filler agglomeration phenomena observed for GRP at high loading, which made nanocomposites have significant enhancement of mechanical and electrical properties using CNF reinforcement.

Early-Age Performance of 3D Printed Carbon Nanofiber and Carbon Microfiber Cement Composites

3D printed cement composites with and without carbon nanofiber (CNF) and microfiber (CF) reinforcement within the cement ink were evaluated at seven days and compared with their traditionally cast counterparts. A liquid lubrication layer at the extrusion nozzle was noted. The reinforcement type influenced the formation of the extruded filament, with underextrusion seen during 3D printing with the CNF cement ink while sudden discontinuation of extrusion was experienced during 3D printing with the CF cement ink. No noticeable interfacial region between printed filaments was observed in the 3D printed cement composites, with the exception of air cavities between printed filaments of the composite fabricated with the CNF cement ink. Lower compressive strengths were seen in the direction orthogonal to the print path for the 3D printed composites compared with the cast composites. The addition of CFs within the cement ink reduced this strength difference and led to strain softening in the post peak behavior.

Loading rate effects on mode-I delamination in glass/epoxy and glass/CNF/epoxy laminated composites

The main objective of the present study is to assess the loading rate effects on mode-I delamination growth in glass/epoxy laminated composites. Furthermore, hybrid reinforcement of these composites by incorporating carbon nanofibers (CNFs) was followed to enhance the interlaminar fracture resistance and affect its loading rate sensitivity. Experiments on DCB specimens made of glass/epoxy and glass/CNF/epoxy laminated composites were conducted by varying the loading rate from standard quasi-static testing up to 200 mm/sec crosshead speed in a servo-hydraulic test machine. More than 21% decrease was observed in the propagation fracture toughness of the glass/epoxy samples due to loading rate elevation in the studied range. Moreover, the results of the present study clearly show the benefits of CNF modification, not only in enhancing the fracture toughness but also in reducing the loading rate dependency. Adding CNFs to glass/epoxy composites caused 32.8% and 13.5% increase in the quasi-static values of the initiation- and propagation-interlaminar fracture toughness (GIC), respectively. Also, owing to CNF incorporation, the maximum drop in the propagation fracture toughness at elevated loading rates was decreased to 8%. Fractography inspections were performed to provide an in-depth explanation for the observed loading rate effects and the advantages of CNF reinforcement.

Structural performance of steel-concrete sandwich beams with carbon nanofiber reinforcement

Cementitious materials such as concrete are typically characterised as quasi-brittle with low tensile strength and low strain capacity, which hence affect the long-term durability of the structure. One of the most important issues in designing and maintaining massive concrete structures like offshore and nuclear power plants is concrete cracking, which is due to the low tensile strength of concrete. This can destroy the structural aesthetic and lead to deterioration of the structure.The addition of fibers to concrete has been proven to be a good mean to control its crack behaviour and maintain its ductility in tension. Further, since the discovery of carbon nanotubes/fibers (CNT/CNF), they have been also considered as efficient fibers for construction materials such as concrete.This study presents the structural performance of steel-concrete (SC) elements with a fiber reinforced concrete (FRC) core using both single and hybrid fibers (i.e. consisting of two types of fibers). For this study carbon nanofibers, and steel fibers which are conventionally used in practice, are used for the FRC. Static tests were conducted on eight SC beams with different concrete types. The paper reports on the experimental results obtained from four-point flexural loading of the SC beams. The study shows considerable improvement for both the strength and ductility of the tested specimens. The research laid the groundwork for additional in-depth studies on using carbon nanofiber reinforced concrete within structural members.

Piezoresistive nanocomposite films for foot strike data monitoring

It is important to understand the human gait especially for the patients under rehabilitation or in old age. Foot strike data is considered as the most important parameter to analyse gait. Piezoresponsive sensors are mostly used for this purpose. In this study, carbon nanofiber (CNF) based thermoplastic polyurethane (TPU) piezoresistive, nanocomposite films (15%, 20% and 25% w/w) were prepared, characterized and tested to study their suitability for such applications. Scanning electron microscope (SEM) studies on the cross section of nanocomposite films revealed that the CNF is well connected inside the TPU matrix. This well connected conducting network resulted in low bulk resistivity (98 ± 3.2 Ω-cm) and impedance (∼250 Ω). The compressive test results indicate more than threefold increase in strength due to CNF reinforcement. All the films showed excellent thickness recovery under cyclic loading while, 25% (w/w) CNF dispersed nanocomposite films’ showed more than 99% recovery after 100 cycles of cyclic compression. The samples also showed good dynamic mechanical stability from 1 to 10 Hz at body temperature (37 °C). The change in resistance under cyclic compression up to 70% strain was found to be linear with high correlation (R2 = 0.99). The gauge factor (up to 1.40 ± 0.03) shows little variation at different strain regions. A cyclic load setup was designed and fabricated to mimic the cyclic foot strike pattern of human gait. The nanocomposite films were tested at three different cyclic strain levels using the setup and the responses were monitored for 2 h using cathode ray oscilloscope (CRO). It has been observed that with the increase in CNF concentrations, the change in voltage goes up to 911.8 mV. The consistency of voltage response under cyclic compressive loading demonstrated in this work shows tremendous potential for these nanocomposite films to be successfully used for piezoresponsive applications of human gait monitoring.

Interlaminar microstructure and mechanical response of 3D robust glass fabric-polyester composites modified with carbon nanofibers

The present work explores new methodology of fabricating the polymer nanocomposite with improved interlaminar, dynamic and micro mechanical properties. Varying amount of carbon nanofibers (CNF) were filled into the glass fiber/unsaturated polyester composite using filtering membrane vacuum-assisted method. Microporous nylon membrane was used to improve the dispersion of CNF in the lamination panels. CNF reinforcement and its concentration had a significant effect on the properties of the composites. Electron microscopy studies on delamination and nanofillers dispersion showed improved interfacial adhesion with CNF filled composites. The end-notched flexure and short-beam strength tests were performed to assess the effect of filling CNF on the interlaminar fracture properties of the composites. Existence of critical concentration was observed for the reinforcement of nanofiller. The properties of the composite enhance with increase in reinforcement upto critical concentration, beyond which it decreases. Better storage modulus (∼57%) and improved interlaminar properties (∼89%) were consistently observed with 2 wt% CNF filled nanocomposite irrespective of the glass fiber loading, besides, the thermal stability and char yield which were also improved significantly. Nanoindentation study shows 39% and 26% increase in elastic modulus and hardness of the composite respectively, on reinforcement of 2 wt% CNF.

Influence of surface activated carbon nano fiber on thermo-mechanical properties of high performance polymeric nano composites

This investigation highlights the influence of plasma modified carbon nano fiber (CNF) on the various properties of poly ether ketone (PEK). CNFs were modified with oxygen plasma under low pressure to enhance the interfacial adhesion between the reinforcement and matrix. Significant changes are evident in the elemental composition of oxygen and carbon on the plasma modified CNFs as observed by X-ray photo electron spectroscopy. Based on results from compression and tensile strength, significant change in the mechanical properties of the composites is observed. Dynamic mechanical thermal analysis (DMTA) reveals that the storage modulus increases on reinforcing modified CNF in PEK. The increase in modulus is noticeable only up to 1.5% wt reinforcement of CNF, while higher percentage of reinforcement leads to decline in properties. DMTA studies also clearly shows that the dispersion of CNF is not uniform after 1.5% of CNF reinforcement. However, differential scanning calorimeter and thermo gravimetric analysis studies reveal that the thermal properties of the CNF reinforced composite do not vary significantly. Thermal conductivity results show a substantial increase in the thermal conductivity of polymeric composites on increasing the reinforcements. Transmission electron microscopy (TEM) analysis reveals that there is uniform dispersion of CNF in PEK. TEM also clearly shows that higher percentage of CNF leads to agglomeration. Physico-chemical analysis indicates that the contact angle increases on increasing the reinforcements. These findings would be highly useful to make way for PEK composites for high temperature and high strength application.

Accelerated environmental degradation and residual flexural analysis of carbon nanofiber reinforced composites

Hollow particle filled composites known as syntactic foams presently find numerous applications in structures exposed to high moisture and high temperature environments. Carbon nanofiber (CNF) reinforcement is attractive in these composites because of the possibility of increased strength with negligible density variation. In the present study, syntactic foams containing 15–50 vol% glass microballoons (GMB) and 1–5 wt% CNF reinforcement as well as CNF/epoxy composites containing 1–5 wt% CNF were exposed to accelerated weathering by immersion in 90 °C water for two weeks and characterized for their residual flexural properties. In the worst performing composites, a maximum weight gain of 3.5% and 10% was observed for CNF/epoxy and CNF/syntactic foam composites, respectively. The syntactic foams tested were observed to generally decrease in strength after weathering with the exception of the composites containing 5 wt% CNF and 15 vol% GMB, which were observed to increase in strength by 41–51% after weathering. The composite containing 5 wt% CNF was also shown to increase in strength by 27% after weathering. Strength retention is attributed to the presence of CNF, along with competing weathering effects on composite structure and morphology.

Thermally stable electromagnetic interference shielding material from polysulfone nanocomposites: Comparison on carbon nanotube and nanofiber reinforcement

The present investigation aims to develop thermally stable electromagnetic interference shielding materials from polysulfone (PSU) nanocomposites filled with multiwall carbon nanotubes (MWCNT) or carbon nanofibers (CNF). The effect of filler type and their structural features such as aspect ratio (length/diameter) and wall integrity on the different properties of nanocomposites has been investigated. Nanocomposite filled with MWCNT/CNF exhibits higher thermal stability compared with the neat PSU matrix. The onset degradation temperature of PSU at 532°C enhances to 537 and 538°C at 3 wt% MWCNT and 3 wt% CNF loading, respectively. CNFs filled nanocomposite shows higher electromagnetic interference shielding effectiveness (EMISE) compared with MWCNT filled one at the same filler loading. Compared with MWCNT, CNF imparts lower electrical percolation threshold. Nanocomposite filled with MWCNTs possesses percolation threshold at 1.5 wt%, whereas nanocomposite filled with CNFs possesses the same at 0.9 wt%. The EMISE of 20–45 dB are obtained from only 1 mm thick CNF filled nanocomposites from the filler loading 3 to 10 wt%. This value of EMISE above 40 dB suggests that the prepared nanocomposite can be used as an effective lightweight EMI shielding material for high frequency (8.2–12.4 GHz) applications, where high thermal stability is required. POLYM. COMPOS. 36:566–575, 2015. © 2014 Society of Plastics Engineers

Research on Properties of CNF/Glass Fiber/Epoxy Composites

In the present investigation, carbon nanofibers (CNF) were dispersed in epoxy matrix to form CNF/glass fiber/epoxy composites. Before blending, CNF was oxidated to get more functional groups on CNF and improve the interface combination between resin and CNF, the infrared spectrum was used to test the efficiency. After that, tensile modulus tests were carried on for CNF/glass fiber/epoxy composites with different CNF fractions, the results indicated that there were slight improvements of tensile modulus when adding CNF. At 3.0 wt% of CNF, composites have the high improvement of tensile modulus, but the reinforcement of CNF decreased at 5.0 wt% of CNF. And the CNF reinforcement efficiency was analyzed using modified Coxs model and rule of mixture.

カーボンナノファイバー強化アルミニウム基複合材料の作製法と機械的性質

カーボンナノファイバー強化アルミニウム基複合材料の作製法と機械的性質

Effect of carbon nanofiber reinforcement on electromagnetic interference shielding effectiveness of syntactic foam

A novel carbon nanofiber (CNF)-reinforced syntactic foam (CNFRSF) was fabricated. The electrical conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of CNFRSF with various volume fraction of CNFs (0–2.0 vol%) were evaluated experimentally. The measurement of EMI SE was carried out in a frequency range of 30 MHz to 1.2 GHz. The experimental results showed that the SE of CNFRSF increases with increase of CNFs content and CNF is more effective in providing EMI shielding compared to chopped carbon fiber and long carbon fiber due to the larger aspect ratio. The CNFRSF having 2.0 vol% CNFs has a SE of 25 dB, which is good enough for most practical applications. Compared to CNFs composites, the EMI SE of CNFRSF has been enhanced by the presence of hollow carbon microspheres. The underlying mechanism is discussed in detail.

Effect of carbon nanofiber reinforcement on mechanical properties of syntactic foam

The effect of carbon nanofiber (CNF) content on mechanical properties of syntactic foams was evaluated experimentally. Compression, flexural, and fracture toughness tests were performed to observe the mechanical behaviors of CNF reinforced syntactic foams (CNFRSFs). Results showed that no enhancement in compressive strength with addition of CNFs was observed. The flexural strength and fracture toughness increased with the increase in CNFs content. The decreasing trend occurred beyond 1.5vol% of CNFs addition, which is ascribed to the agglomeration and clustering of CNFs. The toughening mechanisms, such as crack deflection, step structure, and debonding were proposed and the specific properties of CNFRSFs were also discussed in this paper.

A Review on Nanomaterial Dispersion, Microstructure, and Mechanical Properties of Carbon Nanotube and Nanofiber Reinforced Cementitious Composites

Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) and nanofibers (CNFs) have motivated the development of advanced nanocomposites with outstanding and multifunctional properties. After achieving a considerable success in utilizing these unique materials in various polymeric matrices, recently tremendous interest is also being noticed on developing CNT and CNF reinforced cement‐based composites. However, the problems related to nanomaterial dispersion also exist in case of cementitious composites, impairing successful transfer of nanomaterials′ properties into the composites. Performance of cementitious composites also depends on their microstructure which is again strongly influenced by the presence of nanomaterials. In this context, the present paper reports a critical review of recent literature on the various strategies for dispersing CNTs and CNFs within cementitious matrices and the microstructure and mechanical properties of resulting nanocomposites.

Wear of Carbon Nanofiber Reinforced HDPE Nanocomposites Under Dry Sliding Condition

High density polyethylene (HDPE) is widely used as a bearing material in industrial application because of its low friction and high wear resistance properties. Carbon nanofiber (CNF) reinforced HDPE nanocomposites are promising materials for biomedical applications as well, such as being the bearing materials in total joint replacements. The main objective of the present study is to investigate how the wear of HDPE can be altered by the addition of either pristine or silane treated CNFs at different loading levels (0.5 wt. % and 3 wt. %). Two types of silane coating thicknesses, 2.8 nm and 46 nm, were applied on the surfaces of oxidized CNFs to improve the interfacial bonding strength between the CNFs and the matrix. The CNF/HDPE nanocomposites were prepared through melt mixing and hot-pressing. The coefficients of friction (COFs) and wear rates of the neat HDPE and CNF/HDPE nanocomposites were determined using a pin-on-disc tribometer under dry sliding conditions. The microstructures of the worn surfaces of the nanocomposites were characterized using both scanning electron microscope (SEM) and optical microscope to analyze their wear mechanisms. Compared with the neat HDPE, the COF of the nanocomposites were reduced. The nanocomposite reinforced with CNFs coated with the thicker silane coating (46 nm) at 0.5 wt. % loading level was found to yield the highest wear resistance with a wear rate reduction of nearly 68% compared to the neat HDPE.