Interpreting of effective interphase depth in carbon nanofiber polymer composites by the amount of conduction transferring via an incomplete interphase: A unique method to optimize the charge transferring

Fiber-reinforced polymer (FRP) composites are increasingly used in concrete structures owing to their superior corrosion resistance. However, FRP-reinforced concrete (RC) structures exhibit less ductile response compared to steel RC structures. Recently, the use of basalt fiber reinforced concrete (BFRC) reinforced with BFRP bars was investigated to achieve a reasonable level of ductility in BFRC-BFRP one-way slabs. The shear behavior of such a slab depends on different design parameters. This paper aims to identify the impact of each design parameter on the shear behavior of BFRC-BFRP one-way slabs using a fractional factorial design of experiment (DOE). A 3D finite element model was first developed and validated against available experimental results. The developed model is then used to conduct a sensitivity analysis considering five significant factors that influence the shear behavior of BFRC-BFRP one-way slabs. These factors are the longitudinal reinforcement ratio, shear span-to-depth ratio, effective depth, concrete compressive strength, and volume fraction of BMF. Finally, a design equation that can predict the shear capacity of one-way BFRC-BFRP slabs was proposed based on genetic algorithm. The proposed model showed the best prediction accuracy compared to the available design codes and guidelines with a mean Vpred/Vexp of 0.97 and a COV of 17.91%.

The rapidly evolving field of nanotechnology has sparked a great level of interest and enthusiasm from the research and industrial community. Given the enormous promise that engineered nanomaterials and nanoproducts offer, it is essential to investigate the potential life cycle environmental impacts of emerging nanotechnologies for guiding their sustainable development. One rapidly emerging class of engineered nanoscale materials is carbon nanofibers (CNFs). While studies regarding the toxicological impacts of CNFs are needed, holistic understanding of the impact of CNFs and nanoproducts using systems analysis is central for their safe and sustainable development. Systems analysis with life cycle thinking offers a good tool for evaluating the broader impacts of emerging technologies at an early stage of research. This chapter will examine the needs, challenges, and promises of life cycle assessment (LCA) in the evaluation of CNFs and CNF-based products. A general introduction to LCA is explained in the first part of the chapter and the challenges and promises for the LCA of nanoproducts are identified. The use of LCA in guiding sustainable development of nanotechnology is illustrated in greater detail with a discussion on LCA of CNFs in section 2. Section 3 describes the life cycle energetic impacts of the use of CNFbased polymer composites in auto body panels as a potential replacement for traditional materials. A brief discussion of the toxicological impacts of CNFs is presented in section 4. Section 5 summarizes the major findings and provides directions for future research. Nanotechnology is a fast emerging technology with large number of consumer goods containing engineered nanomaterials already in production [1, 2]. The potential impact of nanotechnology derives from the fact that unprecedented material properties are being discovered in nanoscale materials that enable a broad spectrum of novel applications. One such class of materials is carbonaceous nanomaterials. The last 25 years have seen the discovery of a variety of carbonaceous nanomaterials including fullerenes, nanotubes, nanohorns, and nanofibers [3]. Carbon Nanofibers (CNFs) belong to a new class of materials that have exceptional mechanical properties like high tensile strength (12000 MPa) that is approximately 10 times that of steel [4, 5]. Besides mechanical strength, CNFs possess novel electrical properties like high electrical conductivity. These properties of CNFs are being explored in a variety of ways by imparting functionalities in various intermediate and final value-added consumer products. Applications include the use of CNFs as reinforcements for high strength polymer nanocomposites, use in carbon-lithium batteries, and electrically

N/O-bridge stimulated robust binding energy and fast charge transfer between carbon nanofiber and NiCo LDH for advanced supercapacitors

The paper reviews graphitic carbon nitride-based nanostructured photocatalytic materials and nanofibres for applications in water purification. Titanium dioxide has shown unique features that continue to attract research and development (R&D) due to its unique properties such as availability, ultraviolet absorptivity, photocatalysis, adsorption of pollutants and solar cell engineering. Graphitic carbon nitride is an attractive photocatalyst due to its non-toxicity characteristics, good visible light absorption and good thermal and chemical stabilities. In water purification, nanofibres are currently noticed due to their distinctive properties of effective separation and sometimes elimination of organic pollutants in water. In this review, synthesis and utility of doped titanium dioxide and carbon nitride with metal nanoparticles and polymeric nanofibres from nanocomposites as effective materials for the degradation of organic contaminations from water are discussed. The history, current trends and future perspectives are highlighted.

A biomimetic approach to improve the dispersibility, interfacial interactions and toughening effects of carbon nanofibers in epoxy composites

This research focuses on elucidating on the processing-structure-property relationship in hierarchically-structured polymer composites that are being developed for multifunctional structures. This is accomplished through characterization of the transition in mechanical behavior that occurs across length scales and compositions by: (a) development of model hierarchically-structured composite materials using a combination of model nanoscale and microscale ingredients (carbon nanofibers (CNFs) and carbon microfibers (CMFs)) reinforcing a High Impact Polystyrene (HIPS) thermoplastic polymer that can be extruded or solvent processed, (b) characterization and modeling of the transition compositions in the polymer nanocomposites through melt rheology, and (c) the effect of the CNF on the dynamic compressive behavior of CMF-reinforced polymer composites.

Investigation on the spring-in phenomenon of carbon nanofiber-glass fiber/polyester composites manufactured with vacuum assisted resin transfer molding

There is ever-increasing demand for energy worldwide. The constant use of energy particularly in portable devices and vehicles has required highly efficient and high-capacity energy storage. Materials research is at the front of addressing the society’s demand for energy storage. This chapter focuses on the fabrication and use of polymer and carbon-based nanofibers for energy storage. The widely used fabrication methods such as chemical vapour deposition, electrospinning and the recently developed methods including controlled freezing and gelation for nanofibers have been described. Upon the preparation of polymer nanofibers, carbon nanofibers can be produced by pyrolysis under inert atmosphere. We then review the applications of carbon-based nanofibers in different types of rechargeable batteries and supercapacitors. The chapter is completed with conclusion and outlook.

Polymeric nanofibers as one of the most known nanotechnology products have huge potential applications in many fields due to their high aspect ratio and porosity, being capable of formation of three-dimensional structures and having great mechanical and biological properties. Chitosan is a natural abundant polymer which has attracted huge interests in biomedical and biological industries due to its biocompatible, biodegradable, and non-toxicity properties. However, electrospinning of chitosan is found to be a great challenge, blending it with other polymers such as gelatin was explored as means to improve the morphological deficiencies of chitosan nanofibers and facilitate its electrospinnability. On the other hand, montmorillonite (MMT) has been attracted great attention due to its remarkable improvement in properties of polymeric composites nanofibers. The main objective of this work was on effect of concretion of gelatin–chitosan blends and MMT on morphology of resulted nanocomposite nanofibers. The x-ray diffraction data demonstrated the exfoliation of MMT layers. The morphology of electrospun chiosan–gelatin–MMT composite nanofibers was characterized using scanning electron microscope (SEM). The miscibility of blend was determined using SEM and Fourier transform infrared spectrometer/attenuated total reflectance.

Hierarchical nitrogen‐doped multichannel carbon nanofibers for efficient potassium–selenium batteries

A zero-resistance ammeter circuit with a 10-channel operational amplifier was used to measure the current distribution during a discharge of 10 to 100 mA with simulated zinc porous electrodes in 7.24 M KOH saturated with ZnO. The reaction distribution was found to be highly nonuniform, with 70 to 78% of the charge transfer reaction completed in a depth of 0.01 cm. The high nonuniformity of the initial reaction profile was believed to be due to low conductivity of the electrolyte in the electrode pores. The current distribution changes during passivation of the electrode were experimentally obtained. A mathematical model based upon a macroscope averaging technique was used to predict the time dependence of charge transfer reaction profiles. With mathematical model, current distributions and overpotentials were predicted as a function of time for the segmented zinc electrode discharged at a current of 10 to 100 mA; for these predictions, assumed values of both precipitation rate constants for porous ZnO and diffusion coefficients for hydroxide and zincate ions were used. A gradual decrease in the specific conductivity of the pore electrolyte to 20% of the initial value during discharge yields predictions of current distributions and overpotentials in good agreement with the experimental data. The extent of reduction in the specific conductivity of the pore electrolyte implies a supersaturation of zincate of four times chemical saturation, which was been observed experimentally.At high discharge current (25 to 100 mA), the passivation behavior of the electrode has been simulated. The results of the experiments and mathematical model show that the effective reaction penetration depth is less than 0.02 cm.

Derivation of both EDLC and pseudocapacitance characteristics based on synergistic mixture of NiCo2O4 and hollow carbon nanofiber: An efficient electrode towards high energy density supercapacitor

ABSTRACTCarbon nanofibers were well aligned in polymer composite magnetically at moderate fields up to 3 T. Due to the NiO-coating, carbon nanofibers exhibited strong magnetic moments that lead to alignment. Both TEM and SEM results showed the well-aligned nano-fibers in a polymer matrix. Mechanical testing showed a pronounced anisotropy in tensile strength in directions normal (12.1MPa) and parallel (22MPa) to the applied field, resulting from the well-aligned nanofibers in the polymer matrix. The mechanism of magnetic alignment due to coating of NiO on the nano fiber surface is discussed.

Boron (specifically 10B) is the element of choice to shield thermal neutrons due to its large (n, α) cross‐section; however, very few polymer composites containing high boron concentrations are available. This study aimed to determine the maximum possible amount of boron that could be introduced into a polymer matrix. Diverse manufacturing techniques, ranging from additive manufacturing to compression molding, were employed to fabricate inks and filaments for 3D printing, foams, and flexible pads. Composites using siloxanes, poly(lactic acid), and acrylonitrile butadiene styrene containing up to 80 wt% boron were sucessufully fabricated. The addition of known plasticizers (polyethylene glycol) and reinforcing agents (carbon nanofibers and fumed silica) helped to overcome fabrication problems such as clogging of the printing nozzle or crumbling of compression molded parts. In addition, the thermal‐mechanical properties of these novel boron composites were determined and shown to vary according to boron concentration, presence of additives, and fabrication techniques utilized.

Polymer composites based on high density polyethylene (HDPE) and carbon nanofiber (CNF) were fabricated by melt compounding. The dependences of electrical conductivity of HDPE-CNF composites on filler concentration, temperature, and applied electric field were investigated. The results showed that the conductivity of the HDPE-CNF composites follows the scaling law of percolation theory. Increasing temperature caused a sharp increase in the resistivity of HDPE-CNF composites near the melting temperature of HDPE, yielding a positive temperature coefficient (PTC) effect of resistance. The potential mechanisms involved in the PTC effect of such composites were analyzed. An investigation of the effect of electric field on the conductivity of HDPE-CNF composites revealed the presence of tunneling conduction. The tunneling conductivity increased with increasing filler content because of high tunneling frequency, and decreased with rising temperature as a result of gap widening between conducting CNF fillers.