Search results

This paper aims to study the synergistic effect of self-assembled carboxylic acid-functionalised carbon nanotube (CNT) and nafion/silica nanofibre nanopaper on the electro-activated shape memory effect (SME) and shape recovery behaviour of shape memory polymer (SMP) nanocomposite.

Carboxylic acid-functionalised CNT and nafion/silica nanofibre are first self-assembled onto carbon fibre by means of deposition and electrospinning approaches, respectively, to form functionally graded nanopaper. The combination of carbon fibre and CNT is introduced to enable the actuation of the SME in SMP by means of Joule heating at a low electric voltage of 3.0-5.0 V.

Nafion/silica nanofibre is used to improve the shape recovery behaviour and performance of the SMP for enhanced heat transfer and electrical actuation effectiveness. Low electrical voltage actuation and high electrical actuation effectiveness of 32.5 per cent in SMP has been achieved.

A simple way for fabricating electro-activated SMP nanocomposites has been developed by using functionally graded CNT and nafion/silica nanofibre nanopaper.

The outcome of this study will help to fabricate the SMP composite with high electrical actuation effectiveness under low electrical voltage actuation.

This article aims to present a systematic and up-to-date account of carbon-based reinforcements, including carbon nanotube (CNT), carbon nanofibre (CNF), carbon black (CB), carbon fibre (CF) and grapheme, in shape-memory polymer (SMP) for electrical actuation.

Studies exploring carbon-based reinforcement in SMP composites for electrically conductive performance and Joule heating triggered shape recovery have been included, especially for the principle design, characterisation and shape recovery behaviour, making the article a comprehensive account of the systemic progress in SMP composite incorporating conductive carbon reinforcement.

SMPs are fascinating materials and have attracted great academic and industrial attention owing to their significant macroscopic shape deformation in the presence of an appropriate stimulus. The working mechanisms, the physico requirements and the theoretical origins of the different types of carbon-based reinforcement SMP composites have been discussed. Current research and development on the fabrication strategies of carbon-based reinforcement SMP composites have been summarised.

A systematic review is to evaluate carbon-based reinforcements in SMPs for electrical actuation and discuss recent developments and future applications.

Carbon-based reinforcements in SMPs can be used as smart deployable space structure in the broad field of aerospace technologies.

To reveal the research and development of utilising CNT, CNF, CB, CF and grapheme to achieve shape recovery of SMP composites through electrically resistive heating, which will significantly benefit the research and development of smart materials and systems.

The purpose of this paper is a study aimed at overcoming the interface issue between nanopaper and polymer matrix in shape-memory polymer (SMP) composite laminates caused by their large dissimilarity in electrical/thermal conductive properties. The study attempted to develop an effective approach to fabricate free-standing carbon nanofibre (CNF) assembly in octagon shape formation. The structure design and thermal conductive performance of the resulting octagon-shaped CNF assembly were optimised and simulated.

The CNF nanopaper was prepared based on a filtration method. The SMP nanocomposites were fabricated by incorporating these CNF assemblies with epoxy-based SMP resin by a resin-transfer modelling technique. Thermal conductivity of the octagon-shaped CNF assembly was simulated using the ANSYS FLUENT software for structure design and optimisation. The effect of the octagon-shaped CNF on the thermomechanical properties and thermally responsive shape-memory effect of the resulting SMP nanocomposites were characterised and interpreted.

The CNF template incorporated with SMP to achieve Joule heating triggered shape recovery at a low electric voltage of 3-10 V, due to which the electrical resistivity of SMP nanocomposites was significantly improved and lowered to 0.20 O·cm by the CNF template. It was found that the octagon CNF template with 2 mm width of skeleton presented a highest thermally conductive performance to transfer resistive heat to the SMP matrix.

A simple way for fabricating electro-activated SMP nanocomposites has been developed by using an octagon CNF template. Low electrical voltage actuation in SMP has been achieved.

The fabricated CNF template, the structure design and analysis of dynamic thermomechanical properties of SMP are novel.

The purpose of this paper is to study the effect of alignment of conductive particles on the piezoresistivity of composite based on a theoretical model. The piezoresistivity of composite is associated with the characteristics of conductive network formed by the conductive particles distributed in the composite, which can be changed through aligning the conductive particles.

The orientations of the tunnel resistors formed by each two adjacent conductive particles are dependent on the aligned level of the conductive particles, and different orientations induce different deformations for a tunnel resistor under external strain, which determines the piezoresistivity of the composites. To investigate the resistance behavior of composites with various characteristics of conductive networks, a piezoresistivity model is developed in this paper by considering the aligned level of conductive particles.

The results obtained from the proposed piezoresistivity model indicate that the sensitivity and stability of composites can be enhanced through aligning the conductive particles. Also, the piezoresistivity of composites filled with randomly distributed conductive particles is isotropic, and it turns to be anisotropic when the conductive particles are aligned.

The change and its mechanism of the piezoresistivity upon the aligned level of conductive particles have been pointed out in this paper based on the proposed model. The achievement of this paper will help the people understand, predict and optimize the piezoresistivity of composites, and provide a new approach to design a strain sensor based on the piezoresistivity.

The overall purpose of this research paper largely depends on developing an easy method to synthesis a material suitable for supercapacitor application. This paper includes the synthesis of, α-Co(OH)₂, its structural, elemental and morphological properties and its supercapacitor properties.

Firstly, the electrolyte is prepared using binder free method, then electrodeposition is used to synthesize α-Co(OH)₂ at 2 V. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) are used to study the structural, elemental and morphological characteristics. The supercapacitor properties are investigated by using cyclic voltammetry, charging-discharging graph, stability test and electrochemical impedance spectroscopy (EIS).

Synthesis of α-Co(OH)₂ is a tedious job as the temperature and use of weak base plays an important role. However, throughout electrodeposition, temperature is maintained using a water bath and weak base as the precursor. The presence of nitrate anions shows more interlayer space than that of ß-Co(OH)₂ because of which free diffusion of the electrolyte is possible. Sheets structures are more visible in SEM images. Nanosheet like structure is observed in the film and such kind of structure provide higher surface area and higher specific capacitance. Usually, the surface morphology of cobalt hydroxide shows flower-like, spherical and nanocubes particles. The cross-section of the deposited film and it is found to be approximately 100 µm. In the forward and backward scan, oxidation and reduction peaks are clearly visible. However, such a behavior is reported as stable because of no further peaks of oxidation.

XRD and EDS confirms the growth of α-Co(OH)₂. SEM images shows the porous nature of the film. Specific capacitance and energy density has been estimated at 5 mV s⁻¹ is 780 F g⁻¹ and 82 W h kg⁻¹, respectively. The film was stable for 600 cycles showing 75 per cent capacitance retention. The voltage drop is 0.02 V for 0.5 A cm⁻², indicating low resistance and good conductivity of the film. The specific power is estimated to be 15 W kg⁻¹ for 1 A cm⁻². The value of R_ESR, R_CT, C_DL and W is 4.83 Ohm, 1.273 Ohm, 0.00233 C and 0.717, respectively. Thus indicating α-Co(OH)₂ to be better candidate for supercapacitor applications.

Development of high efficiency nanofibrous air filter membrane by electrospinning process, to address the air pollution (both the particulate matter and the gaseous components) problem, which has become a major environmental concern.

By exploiting the advantage of active sites on soy protein isolate (SPI), the very high surface area of micro-pore rich activated carbon (AC) and the biocompatibility and biodegradable nature of polyvinyl alcohol (PVA). The authors have developed a SPI/AC/PVA hybrid membrane. Spun-bond nonwoven substrate was used as the support material to enhance the mechanical properties and also the filter handling properties. The properties of nanofibrous membrane including morphology, air permeability, filtration efficiency and formaldehyde absorption test were carried out as per standard test methods.

SPI-based membrane offers a great potential in air filtration/purification applications. Its potential to capture glancing pollutants at the molecular level is because of the presence of numerous functional groups on the soy protein surface, which enhances the adsorption of particulate matter and toxic gases, even bacteria and viruses to its surface.

The results are anticipated to provide a potential method to promote the development of a nanofibrous membrane, which can act as a high performance, dual function and eco-friendly air filter/purifier.

In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless, FFF parts exhibit some limitations such as lack of accuracy and/or lower mechanical performance. As a result, some alternatives have been developed to overcome some of these restrictions, namely, the formulation of high performance polymers, the creation of fibre-reinforced materials by FFF process and/or the design of new FFF-based technologies for printing composite materials. This work aims to analyze these technologies.

This work aims to study and understand the advances in the behaviour of 3D printed parts with enhanced performance by its reinforcement with several shapes and types of fibres from nanoparticles to continuous fibre roving. Thus, a comprehensive survey of significant research studies carried out regarding FFF of fibre-reinforced thermoplastics is provided, giving emphasis to the most relevant and innovative developments or adaptations undergone at hardware level and/or on the production process of the feedstock.

It is shown that the different types of reinforcement present different challenges for the printing process with different outcomes in the part performance.

This review is focused on joining the most important researches dedicated to the process of FFF-printed parts with different types reinforcing materials. By dividing the reinforcements in categories by shape/geometry and method of processing, it is possible to better quantify performance improvements.

The purpose of this paper is to develop an effective approach to significantly improve the thermomechanical properties of shape memory polymer (SMP) nanocomposites that show fast thermally responsive shape recovery.

Hexagonal boron nitrides (h-BNs) were incorporated into polymer matrix in an attempt to improve the thermal conductivity and thermally responsive shape recovery behaviour of SMP, respectively. Thermally actuated shape recovery behaviour was recorded and monitored instrumentally.

The results show that both glass transition temperature (T_g) and thermomechanical properties of the SMP nanocomposites have been progressively improved with increasing concentration of h-BNs. Analytical results also suggest that the fast-responsive recovery behaviour of the SMP nanocomposite incorporated with h-BNs was due to the increased thermal conductivity.

A simple way for fabricating SMP nanocomposites with enhanced thermally responsive shape recovery based on the incorporation of h-BNs was developed.

The outcome of this study may help fabrication of SMP nanocomposites with fast responsive recovery behaviour.

Growth of nickel tip carbon nanorod by means of pulsed plasma chemical vapor deposition (PPCVD) was carried out at different deposition time. Effects of deposition time under the methane plasma on the growth of carbon nanorod were investigated. The nucleation and growth mechanism of nickel tip carbon nanorod were also discussed. Nanoparticles were formed on substrate to introduce more nucleation sites at an elevated deposition time, and the density of nanorod on the surface of the substrate was greatly increased until the proper methane plasma deposition time. The longest nanorods and the highest nanorods density were found after methane plasma treatment of 3 min and 10 min respectively. Nanorod was about 60 nanometers in diameter and about 550 nanometers in length. Nanorods had onion and V-shape with Ni tip.