Study of the Diffusion Behavior of Seawater Absorption in Multi-Walled Carbon Nanotubes/Halloysite Nanotubes Hybrid Nanofillers Modified Epoxy-Based Glass/Carbon Fiber Composites

In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.

High-cycle Fatigue Life Extension of Glass Fiber/Polymer Composites with Carbon Nanotubes

The present work shows that the addition of small volume fractions of multi-walled carbon nanotubes （CNTs） to the matrix results in a significant increase in the high-cycle fatigue life. It is proposed that carbon nanotubes tend to inhibit the formation of large cracks by nucleating nano-scale damage zones. In addition, the contribution to energy absorption from the fracture of nanotubes bridging across nano-scale cracks and from nanotube pull-out from the matrix are mechanisms that can improve the fatigue life. An energy-based model was proposed to estimate the additional strain energy absorbed in fatigue. The distributed nanotubes in the matrix appear to both distribute damage as well as inhibit damage propagation resulting in an overall improvement in the fatigue strength of glass fiber composites.

A comparative study of polymer nanocomposites containing multi-walled carbon nanotubes and graphene nanoplatelets

Featuring exceptional mechanical and functional performance, MWCNTs and graphene(nano)platelets(GNPs or Gn Ps;each platelet below 10 nm in thickness) have been increasingly used for the development of polymer nanocomposites. Since MWCNTs are now cost-effective at US$30 per kg for industrial applications, this work starts by briefly reviewing the disentanglement and surface modification of MWCNTs as well as the properties of the resulting polymer nanocomposites. GNPs can be made through the thermal treatment of graphite intercalation compounds followed by ultrasonication;GNPs would have lower cost yet higher electrical conductivity over 1,400 S cmthan MWCNTs. Through proper surface modification and compounding techniques, both types of fillers can reinforce or toughen polymers and simultaneously add anti-static performance. A high ratio of MWCNTs to GNPs would increase the synergy for polymers. Green, solvent-free systhesis methods are desired for polymer nanocomposites. Perspectives on the limitations, current challenges and future prospects are provided.

Determination of an Innovative Consistent Law for the Rheological Behavior of Polymer/Carbon Nanotubes Composites

An innovative constitutive model for the rheological behavior of the polymer/carbon nanotubes composites is proposed in this paper. Based on experimental investigations, this consistent law gives the evolution of the composite shear viscosity versus the shear rate, over a large range, and the temperature with various carbon nanotubes mass fractions. Hence, this consistent could be implemented in a finite element code in order to lead many polymer/carbon nanotubes manufacturing process like injection molding or hot embossing.

Flexible piezoresistive pressure sensor based on a graphene-carbon nanotube-polydimethylsiloxane composite

Flexible sensors are used widely in wearable devices,specificallyflexible piezoresistive sensors,which are common and easy to manipulate.However,fabricating such sensors is expensive and complex,so proposed here is a simple fabrication approach involving a sensor containing microstructures replicated from a sandpaper template onto which polydimethylsiloxane containing a mixture of graphene and carbon nan-otubes is spin coated.The surface morphologies of three versions of the sensor made using different grades of sandpaper are observed,and the corresponding pressure sensitivities and linearity and hysteresis characteristics are assessed and analyzed.The results show that the sensor made using 80-mesh sandpaper has the best sensing performance.Its sensitivity is 0.341 kPa-1 in the loading range of 0–1.6 kPa,it responds to small external loading of 100 Pa with a resistance change of 10%,its loading and unloading response times are 0.126 and 0.2 s,respectively,and its hysteresis characteristic is indicating that the sensor has high sensitivity,fast response,and good stability.Thus,the presented∼7%,piezoresistive sensor is promising for practical applications inflexible wearable electronics.

Atomic insights into synergistic effect of pillared graphene by carbon nanotube on the mechanical properties of polymer nanocomposites

Molecular dynamics simulations have been performed to explore the underlying synergistic mechanism of pillared graphene or non-covalent connected graphene and carbon nanotubes(CNTs) on the mechanical properties of polyethylene(PE) nanocomposites. By constructing the pillared graphene model and CNTs/graphene model, the effect of the structure, arrangement and dispersion of hybrid fillers on the tensile mechanical properties of PE nanocomposites was studied. The results show that the pillared graphene/PE nanocomposites exhibit higher Young’s modulus, tensile strength and elongation at break than non-covalent connected CNTs/graphene/PE nanocomposites. The pull-out simulations show that pillared graphene by CNTs has both large interfacial load and long displacement due to the mixed modes of shear separation and normal separation. Additionally, pillared graphene can not only inhibit agglomeration but also form a compact effective thickness(stiff layer), consistent with the adsorption behavior and improved interfacial energy between pillared graphene and PE matrix.

The Influence of Carbon Nanotubes and Nano-Silica Fume on Enhancing the Damping and Mechanical Properties of Cement-Based Materials

This paper conducted experimental studies on the damping and mechanical properties of carbon nanotube-nanosilica-cement composite materials with different carbon nanotube contents. The damping and mechanical properties enhancement mechanisms were analyzed and compared through the porosity structure test, XRD analysis, and scanning electron microscope observation. The results show that the introduction of nanosilica significantly improves the dispersion of carbon nanotubes in the cement matrix. At the same time, the addition of nanosilica not only effectively reduces the critical pore size and average pore size of the cement composite material, but also exhibits good synergistic effects with carbon nanotubes, which can significantly optimize the pore structure. Finally, a rationalization suggestion for the co-doping of nanosilica and carbon nanotubes was given to achieve a significant increase in the flexural strength, compressive strength and loss factor of cement-based materials.

In-situ homogeneous synthesis of carbon nanotubes on aluminum matrix and properties of their composites

Using nickel catalyst supported on aluminum powders, carbon nanotubes （CNTs） were successfully synthesized in aluminum powders by in-situ chemical vapor deposition at 650 ℃. Structural characterization revealed that the as-grown CNTs possessed higher graphitization degree and straight graphite shell. By this approach, more homogeneous dispersion of CNTs in aluminum powders was achieved compared with the traditional mechanical mixture methods. Using the in-situ synthesized CNTs/Al composite powders and powder metallurgy process, CNTs/Al bulk composites were prepared. Performance testing showed that the mechanical properties and dimensional stability of the composites were improved obviously, which was attributed to the superior dispersion of CNTs in aluminum matrix and the strong interfacial bonding between CNTs and matrix.

Composite polymer electrolyte reinforced by graphitic carbon nitride nanosheets for room-temperature all-solid-state lithium batteries

By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.

The Packaging Materials with Carbon Nanotube/Polymer Composites

A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The liquid crystal polymers (LCP) and melamine formaldehydes (MF) polymer are used to study the orientation effect of CNTs in various polymeric matrix.The influences of orientation,aspect ratio,and mass fraction of CNTs upon the shielding effectiveness (SE) of CNTs-composites are investigated.The higher the orientation,aspect ratio,and weight percentages of nano-materials are, the higher the SE of the carbon composites.The highest SE for the CNTs/LCP nano composite obtained is more than 62 dB. This results may lead to the developing for CPU IC chip packaging.

Multifunctional characteristics of 3D printed polymer nanocomposites under monotonic and cyclic compression

This study presents the multifunctional characteristics of multi-walled carbon nanotube(MWCNT)/polypropylene random copolymer(PPR) composites enabled via fused filament fabrication(FFF) under monotonic and quasi-static cyclic compression. Utilizing in-house MWCNT-engineered PPR filament feedstocks, both bulk and cellular composites were realized. The morphological features of nanocomposites were examined via scanning electron microscopy, which reveals that MWCNTs are uniformly dispersed. The uniformly dispersed MWCNTs forms an electrically conductive network within the PPR matrix, and the resulting nanocomposite shows good electrical conductivity(~10^(-1)S/cm), improved mechanical performance(modulus increases by 125% and compressive strength increases by 25% for 8 wt% MWCNT loading) and pronounced piezoresistive response(gauge factor of 27.9-8.5 for bulk samples)under compression. The influence of strain rate on the piezoresistive response of bulk samples(4 wt% of MWCNT) under compression was also measured. Under repeated cyclic compression(2% constant strain amplitude), the nanocomposite exhibited stable piezoresistive performance up to 100 cycles. The piezoresistive response under repeated cyclic loading with increasing strain amplitude of was also assessed.The gauge factor of BCC and FCC cellular composites(4 wt% of MWCNT) with a relative density of 30%was observed to be 46.4 and 30.2 respectively, under compression. The higher sensitivity of the BCC plate-lattice could be attributed to its higher degree of stretching-dominated deformation behavior than the FCC plate-lattice, which exhibits bending-dominated behavior. The 3D printed cellular PPR/MWCNT composites structures were found to show excellent piezoresistive self-sensing characteristics and open new avenues for in situ structural health monitoring in various applications.

Durability Testing of Composite Aerospace Materials Based on a New Polymer Carbon Fiber-Reinforced Epoxy Resin

In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.

Fabrication,microstructures,and properties of copper matrix composites reinforced by molybdenum-coated carbon nanotubes

Multiwalled carbon nanotubes （CNTs） were coated by a molybdenum layer using carbonyl thermal decomposition process with a precursor of molybdenum hexacarbonyl. The Mo-coated CNTs （Mo-CNTs） were added into copper powders to fabricate Mo-CNT/Cu composites by means of mechanical milling followed by spark plasma sintering. The Mo-CNTs were uniform dispersion in the Cu matrix when their contents were 2.5 vo1.%-7.5 vol.%, while some Mo-CNT clusters were clearly observed at additions of 10.0 vo1.%-15.0 vol.% Mo-CNTs in the mixture. The mechanical, electrical, and thermal properties of the Mo-CNT/Cu composites were characterized, and the results showed that the tensile strength and hardness were 2.0 and 2.2 times higher than those of CNT-free specimens, respectively. Moreover, the Mo-CNT/Cu composites exhibited an enhanced thermal conductivity but inferior electrical conductivity compared with sintered pure Cu. The uncoated CNT/Cu composites were fabricated by the similar processes, and the measured tensile strength, hardness, thermal conductivity, and electrical conductivity of the CNT/Cu composites were lower than those of the Mo-CNT/Cu composites.

Mechanical properties of Cu based composites reinforced by carbon nanotubes

Cu based composites reinforced by 0%～25% (volume fraction) carbon nanotubes were prepared.The fracture behaviors and the rolling properties of the composites and the effects of the volume fraction of the carbon nanotubes were studied.The experimental results show that the fracture toughness of the composites is related to the pulling out and bridging of the carbon nanotubes in the fracture process.With the volume fraction of the carbon nanotubes increasing, the Vicker’s hardness and the compactness of the composites increase first and then decrease. The peaks of the hardness and the compactness occur at 12%～15% of volume fraction of carbon nanotubes.Some proper ratio of rolling reduction benefits to the comprehensive mechanical properties of the composites.

Fabrication of carbon nanotubes reinforced AZ91D composites by ultrasonic processing

Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.

Fabrication and thermal conductivity of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.

EBSD characterization of Al7075/graphene nanoplates/carbon nanotubes composites processed through post-deformation annealing

The effects of the post-deformation annealing on the microstructural evolution of hot rolled Al7075 matrix composites reinforced with CNTs and GNPs were investigated.The multi-pass hot rolling was applied on the stir cast samples.Annealing was then applied to the composites at 450℃ for 4 h.Microstructural evolution was examined by SEM,EDS,and EBSD techniques.EBSD data showed that the addition of 0.87 vol.%(GNPs+CNTs)significantly inhibited the occurrence of recrystallization.Also,in the composite with 0.96 vol.%CNTs,recrystallization was partially inhibited.Whereas,in composites with 0.92 vol.%of GNPs,the occurrence of recrystallization through particle stimulated nucleation(PSN)mechanism was significantly accelerated.The volume fraction of recrystallized grains depends significantly on the occurrence of PSN in the presence of reinforcements.The intensity and type of the main components of the texture as well as the FCC fibers depend on the type of reinforcement.

Aluminum matrix composites reinforced by molybdenum-coated carbon nanotubes

To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering.The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated.The results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al powders.The electrical conductivity of the composites decreases with increasing Mo-CNT content.When the Mo-CNT content is 0.5wt%,the tensile strength and hardness of Mo-CNT/Al reach their maximum values.The tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%,while the electrical conductivity only decreases by 7.1%,relative to sintered pure Al.The phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.

Electrical,dielectric and surface wetting properties of multi-walled carbon nanotubes/nylon-6 nanocomposites

This paper reports that the multi-walled carbon nanotubes （MWCNT）/nylon-6 （PA6） nanocomposites with dif- ferent MWCNT loadings have been prepared by a simple melt-compounding method. The electrical, dielectric, and surface wetting properties of the CNT/PA6 composites have been studied. The temperature dependence of the conductivity of the CNT/PA6 composite with 10.0wt% CNT loading （σRT - 10^-4 S/cm） are measured, and afterwards a charge-energy-limited tunnelling model （In σ（T） - T^-1/2） is found. With increasing CNT weight percentage from 0.0 to 10.0 wt%, the dielectric constant of the CNT/PA6 composites enhances and the dielectric loss tangent increases two orders of magnitude. In addition, water contact angles of the CNT/PA6 composites increase and the composites with CNT loading larger than 2.0 wt% even become hydrophobic. The obtained results indicate that the electrical and surface properties of the composites have been significantly enhanced by the embedded carbon nanotubes.

Synthesis and Electrochemical Behaviors of a-MoO_3 Nanobelts/Carbon Nanotubes Composites for Lithium Ion Batteries

α-MoO3 nanobelts/carbon nanotubes（CNTs） composites were synthesized by simple hydrothermal method followed by CNTs incorporating, and characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. Cyclic voltammogram（CV）, electrochemical impedance spectroscopy（EIS）, and galvanostatic charge/discharge testing techniques were employed to evaluate the electrochemical behaviors of α-MoO3 nanobelts/CNTs composites. The results exhibited that compared to bare α-MoO3 nanobelts, the α-MoO3 nanobelts/CNTs composites have better electrochemical performances as cathode materials for lithium ion battery, maintaining a reversible specific capacity of 222.2 mAh/g at 0.3 C after 50 cycles, and 74.1% retention of the first reversible capacity. In addition, the Rct value of the α-MoO3 nanobelts/CNTs is 13 Ω, much lower than 66 Ω of the bare α-MoO3 nanobelts. The better electrochemical performances of the α-MoO3 nanobelts/CNTs composites can be attributed to the effects of the high conductive CNTs network.