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Highly transparent and super-wettable nanocoatings for multifunctional applications with outstanding physical properties are in high demanded. However, such nanocoatings resistant to water invasion and Ultraviolet (UV) weathering remain a significant challenge. In this work, physically durable coatings based on inorganic nanoparticles (NPs) and an organic segment (isocyanate-silane modified surfactant) have been synthesized via a sol-gel approach. It is noteworthy the isocyanate-silane with –NH–C O- functional group creates a strong bonding between the highly hydrophilic surfactant and the inorganic NPs. This in-house synthesized organic segment can render the coating long-lasting wetting properties and resist to be washed away by water, while the inorganic NPs can form sturdy covalent bonds with the nano-scale hierarchical structure on the glazing substrate to improve the durability. This nanocoating demonstrates high transparency with superwetting property (water contact angle, WCA ​= ​4.4 ​± ​0.3°), effective de-frosting performance. Water invasion or UV accelerated weathering tests do not significantly affect the self-cleaning performance of nanocoating. Physical properties, including coating adhesion, hardness, Young's modulus, and abrasion resistance are systematically investigated. Interestingly, this clear coating shows prominent infrared shielding property attributed to Antimony-doped tin oxide (Sb-doped SnO2) NPs. The developed nanocoating process is easy to scale up for larger areas that require multipurpose self-cleaning functions.

When joint inventory positions in an assemble-to-order system are irreducible, it has been proved that the evaluation on order-based backorders can be based on a set of systems under the base stock policy. We provide a new necessary and sufficient condition for the irreducibility of the joint inventory positions where the item inventory is controlled by an ( r , n Q ) policy. The computation complexity of applying this new condition is much lower than that of verifying the previous condition.

Single image super-resolution (SISR) technology can reconstruct a high-resolution (HR) image from the corresponding low-resolution (LR) image. The emergence of deep learning pushes SISR to a new level. The successful application of the recursive network motivates us to explore a more efficient SISR method. In this paper, we propose the deep recursive up-down sampling networks (DRUDN) for SISR. In DRUDN, an original LR image is directly fed without extra interpolation. Then, we use the sophisticated recursive up-down sampling blocks (RUDB) to learn the complex mapping between the LR image and the HR image. At the reconstruction part, the feature map is up-scaled to the ideal size by a de-convolutional layer. Extensive experiments demonstrate that DRUDN outperforms the state-of-the-art methods in both subjective effects and objective evaluation.

A machine learning-assisted composite design framework is established in this paper as an effective and efficient way to find feasible or optimal selections of fiber materials and layup stacking orientations to meet the mechanical and non-mechanical requirements. With a given material database and conventional guidelines for layup design, a generative machine learning model using the physical-informed Conditional Generative Adversarial Networks (CGAN) is developed to provide solutions suitable for various design boundaries such as target strength, maximum deformation, minimum thickness and lowest cost. In order to import the physical constraints in the form of inequalities into the CGAN model, a customized loss along with the traditional loss function of CGAN are applied to the generator for generating outputs that are more favorable to our design requirements as well as conforming to our input data pattern. The networks are trained by using a total of 3000 Finite Element Method (FEM) simulation data from randomly generated composite configurations. Following an evaluation of the training performance of the model, this design strategy is applied to three benchmark problems of a composite tube under different loading conditions and design constraints. The results show that the CGAN model can successfully provide a large number of FRP configurations that fit into the scope of mechanical requirements. In the meanwhile, this integrated CGAN model and FEM system is easily extendable to other composite inverse design scenarios.

Fiber metal laminate (FML) is a sandwich combination of thin metal and a composite layer which possess high fatigue, creep, and corrosion resistance. The performance of FML depends on the bonding behavior between the metal and composite interface (MCI). Introducing Redux 335k polymer interleaf can improve MCI, but cannot retain the mechanical properties after its first delamination. Toughened self-healing co-polymer film EMAA (Ethylene-methacrylic acid) can be used as an alternative due to its self-healing property which can recover the mechanical property after each delamination. Double-cantilever-beam (DCB) test is carried out by supporting a thick CFRP composite as a backing beam to avoid the yielding of thin metal in FML to estimate the interlaminar fracture toughness (G1C) at the MCI. Results from the DCB test shows that the incorporation of EMAA thin film improves G1C at the MCI. However, G1C gradually decreases despite recovering its fracture toughness after each delamination when the self-healing reaction is thermally activated. The Mode I fracture toughness of EMAA before the first heal is 1.95 kJ/m2, which is higher due to its thermoplastic nature. This article emphasizes only on the recovery of Mode I self-healing efficiency of EMAA at MCI. However, the article also shows the fracture toughness at MCI by using non-self-healing film adhesive at MCI. This comparison is to understand that the standard structural adhesive (Redux 335K) cannot retain the mechanical properties after its first delamination, and also to understand the failure modes of both thermosetting and thermoplastic interleaf at MCI.

The fiber phase, matrix phase, and fiber/matrix interphase are different phases of fiber reinforced polymers (FRPs). FRP property such as mechanical strength is highly dependent on the adhesion level between the fiber and matrix for efficient load transfer. In this study, functionalized multiwalled carbon nanotubes (MWCNT) modified dopamine coating solution is coated on the fiber surface as additional sizing to enhance the interfacial bonding strength between ultra-high-molecular-weight polyethylene (UHMWPE) fiber and thermoplastic matrix (Elium®) which has resin infusion capability. The resultant of transverse fiber bundle tests shows that the polydopamine (PDA) coating of fiber with embedded 0.03% of MWCNT can improve the bonding strength of fiber/matrix about 42.50% compared with that of common composites. In contrast, the addition of carbon nanotubes into Elium® matrix shows a distinctly weaker bonding effect than the interphase between neat PDA coating and UHMWPE fiber. This discrepancy is because of densification of carbon nanotubes (CNT) forest grafted on the fiber surface during the nanocomposite coating process. When being compared to other surface modification process, CNT embedded dopamine surface modification is cost effective and less time consuming and has better performance than the modified matrix with the addition of CNTs.

In this work, shear thickening fluid (STF) was fabricated and encapsulated by using three different encapsulation methods for the first time. The mechanical properties of individual STF capsules were investigated to obtain optimal encapsulation method and formula. Much more energy can be absorbed for STF capsules during impact than that of quasi-static compression. The introduction of ultraviolet (UV) curable resin can significantly improve the static strength of STF capsule and thus enhance the handleability of STF capsule. The STF capsules synthesized through the two-step polymerization method show an elastic shell which can stand multiple impacts without any damage. This STF capsule possesses higher static strength and absorbs more strain energy than capsules synthesized through the other two methods. Furthermore, incorporation of the STF capsules into silicone gel enhances the energy absorption capacity of matrix material up to 71.3%. Accepted version

The development of microencapsulation techniques that can microencapsulate a wide variety of aqueous phases with different functions can greatly promote the advancement of microcapsule-based functional materials. Herein, a novel microencapsulation technique to microencapsulate aqueous phases with different functions was successfully established based on the inverse emulsion. Using pure water as the targeting core, the shell formation mechanism was carefully studied for this microencapsulation technique. Different cross-linkers, including glycerol, poly(vinyl alcohol) (PVA), and polyethyleneimine (PEI) with multiple reactive hydrogen atoms, were adopted to adjust the microcapsule quality. It finds that the microcapsules have relatively low quality when no cross-linker was used, and that they became robust when cross-linked agents were adopted. Importantly, the higher the functionality of the cross-linker, the better the impermeability of the microcapsules shell to retain the core content. This technique was applied to microencapsulate common compounds of different nature in the laboratory, including water-soluble organics, water-soluble inorganics, and water-based dispersions, to demonstrate its versatility. It shows that the technique can microencapsulate a wide variety of water-soluble/dispersible substances except for the inorganic strong acid. The established technique opens a window to fabricate high-quality microcapsules containing aqueous phases with diversified functions, promoting the development of microcapsule-based functional materials.

Due to the brittle feature of carbon fiber reinforced plastic laminates, mechanical multi-joint within these composite components shows uneven load distribution for each bolt, which weakens the strength advantage of composite laminates. In order to reduce this defect and achieve the goal of even load distribution in mechanical joints, we propose a machine learning-based framework as an optimization method. Since that the friction effect has been proven to be a significant factor in determining bolt load distribution, our framework aims at providing optimal parameters including bolt-hole clearances and tightening torques for a minimum unevenness of bolt load. A novel circuit model is established to generate data samples for the training of artificial networks at a relatively low computational cost. A database for all the possible inputs in the design space is built through the machine learning model. The optimal dataset of clearances and torques provided by the database is validated by both the finite element method, circuit model, and an experimental measurement based on the linear superposition principle, which shows the effectiveness of this general framework for the optimization problem. Then, our machine learning model is further compared and worked in collaboration with commonly used optimization algorithms, which shows a potential of greatly increasing computational efficiency for the inverse design problem.

In this study, hollow glass bubbles (HGBs) of about 70 μm with through-holes of about 5 μm were successfully separated from a commercialized product and were used as targets to be sealed/covered by GO sheets of size about 24 μm. Firstly, these HGBs were treated with poly(ethyleneimine) (PEI) cross-linked polydopamine (PDA) to positively charge their outer surface. After treatment, the outer surface of HGBs was uniformly deposited with PDA nano-particles. During sealing/covering process, GO sheets were successfully attracted to the PDA modified HGBs by electrostatic force between the negatively charged GO sheets and positively charged HGBs introduced by the deposited PDA nano-particles, and were anchored by PDA nano-particles at the outer surface to avoid sucking of GO sheets into HGBs through the holes. While most of HGBs were tightly sealed/covered, some of them were partially sealed due to the fractured or collapsed GO sheets on the through-holes.

Twist has been well identified as an effective parameter to tune the mechanical behavior of carbon nanotube (CNT) fibers, e.g., tensile strength, strain, modulus and elastic-plastic behaviors. In this contribution, we uncover the twist-induced plastic deformation and failure behaviors of CNT fibers shrunk by ethanol (E-CNT fiber) and polyvinyl alcohol (P-CNT) solutions under low strain rate of 0.001 s−1 and high strain rate of 1300 s−1, which are essentially important for designing high-performance composites with respect to long term stability and short-term collision, respectively. It is found that the strain-induced microstructural evolution processes of CNT fibers depends on twist angle as a result of the strengthening effect of inter-CNT friction and the weakening effect of CNT obliquity. The tensile strength, failure strain and modulus of CNT fibers are more sensitive to strain rate as the twist angle increases. The optimum twist angle provides not only the higher tensile strength, but also the better data repeatability. The numerical results reveal that the brittle/ductile properties of filaments and their interfacial interaction will contribute to the plastic behaviors of a twist fiber. The empirical constitutive equations were built to describe the stress-strain curves of CNT fibers by taking the strain, helical geometry, twist-induced damage and strain rate into consideration.

Self-assembly strategies have been widely used to prepare aerogels from nanoparticles. It is challenging to assemble those nanoparticles whose surface is lack of abundant polar functional groups into aerogels, as the weak interface interactions among nanoparticles are not enough to maintain aerogel structures. Here we demonstrate a liquid extrusion strategy as a possible solution to this challenge, by using a small amount of large-sized graphene oxide and liquid extrusion devices. Large-sized graphene oxide sheets cover, wrap and assemble nanoparticles, and thus promote the assembly of nanoparticles. Extrusion devices are employed to control the shape and size of aerogels. Based on this strategy, a variety of nanoparticle, such as clay nanosheets, boron nitride nanosheets and carbon nanotubes, have been assembled into aerogels with designed shape and size even when there are few polar functional groups on nanoparticle surface. Detailed studies on clay aerogels show that the aerogels have porous structure and high performance, which can be proposed for applications in thermal insulation, fire retardation and absorption, etc. This liquid extrusion strategy can be thought of as effective, general and scalable approach to produce nanoparticle aerogels, particularly for those nanoparticles whose surface is lack of polar functional groups.

A new approach was developed to load 4,4′-bis-methylene cyclohexane diisocyanate in microcapsules, with outstanding stability in thermal and chemical environments, and excellent efficiency for both self-healing and self-lubricating uses. Well-dispersed microcapsules with diameter of 80 ± 22 µm and shell thickness of 3.8 ± 0.2 µm were produced with a core fraction of 74 ± 1.3 wt% as determined by titration. In thermal environments, the microcapsules started to lose 5% mass at 230 °C, which was higher than the boiling point of pure HMDI and thermal decomposition temperature of shell material. In chemical environments (hexane, xylene, ethyl acetate and water), the impermeable microcapsules reserved more than 90% of original core material after 20 days immersion. More interestingly, final microcapsules survived successfully in acetone losing only 25% of core material after 24 h. Parameters including microcapsules size, concentrations, immersion durations and solvent polarity were investigated systematically to obtain the stability of microcapsules in organic solvents. The smart coatings (10 wt% microcapsules) showed outstanding self-healing anticorrosion efficiency in sodium chloride solutions, and their friction coefficient decreased by 80% than control samples.

Materials that change color in response to external stimuli can cater to diverse applications from sensing to art. If made flexible, stretchable and weavable, they may even be directly integrated with advanced technologies such as smart textiles. A new class of engineered composite based on polydiacetylene (PDA) functionalized carbon nanotubes (CNT) shows tremendous potential in this regard. While the inherent multi stimuli chromatic response of the polymer (blue to red) is retained, the underlying conducting CNTs invoke electrochromism in PDA. Further, the fiber form factor of dry-spun CNT yarns facilitate direct weaving of large scale electrochromic fabrics, where current flow and thus color change can be accurately controlled. This review summarizes the fundamental aspects of CNT yarns and PDAs, focusing especially on their interaction chemistry which results in the scientifically and commercially appealing electrochromic transition in these hybrids.

Cheetah skin carbon nanotube, a novel periodically patterned nanocarbon on CNT synthesized as a highly effective filler for fabrication of high performance composites. The advantage of newly developed morphology lies in the fact that the size of nanocarbon on CNT and their distance can be fully controlled based on the application requirements. Cheetah skin CNT shows an excellent thermal stability and dispersibility in a high density polyethylene (HDPE) compared to pristine CNT/HDPE composite, making cheetah skin CNT a suitable candidate for fabrication of high performance HDPE based composite. The addition of cheetah skin CNT into HDPE resulted in a composite with improved thermomechanical properties. Compared with the pure HDPE and HDPE/pristine CNT, storage modulus and loss modulus of HDPE/cheetah skin CNT improved significantly at low temperatures even with very low content of cheetah skin CNT. Also, the thermal stability of the cheetah skin CNT/HDPE was found to be significantly higher than that of pristine CNT/HDPE composite in both isothermal and non-isothermal degradation performed for composites.

This paper presents a novel approach to synthesize microencapsulated phase change materials (MEPCMs) with composite titania-polyurea (TiO2-PUA) shell at low temperature. MEPCM pre-microcapsules with PUA shell were first synthesized through interfacial polymerization in oil-in-water emulsion, followed by deposition of TiO2 on the surface of pre-microcapsules in solution by means of the liquid phase deposition (LPD) method at low temperature. The two-step synthesis approach results in high yield of microcapsules and the MEPCMs with composite TiO2-PUA shell integrate advantages of both organic and inorganic shells. Results show that the MEPCMs have a well-defined core–shell structure with around 73 wt.% of core fraction and dense composite TiO2-PUA shell, which is thermally stable and durable and effectively lowers the evaporation and prevents leakage of the core material even under repeated heating and cooling. The MEPCMs also show mitigated supercooling, faster thermal response, and high thermal storage capacity. TiO2-PUA MEPCM-modified cement pastes showed distinct latent heat storage capacity. ASTAR (Agency for Sci., Tech. and Research, S’pore)

This investigation examines the influence of fiber type on the failure of titanium-based fiber metal laminates (FMLs). Two types of FMLs, comprising fiber-based composite layers, sandwiched between titanium sheets, were subjected to impact by a 12 mm steel sphere at various velocities ranging from 100–400 m/s. The first FML incorporated carbon fiber reinforced plastic (CFRP) layers, whereas the second had hot-pressed ultra-high-molecular-weight polyethylene fiber (UHMWPE, Dyneema®HB50) layers as the sandwiched component. FML specimens were clamped between annular plates, which exposed a circular target, and impacted at the center by spherical projectiles. Optical images of the deformation and failure induced in the two types of FMLs were captured by a high-speed camera, and the respective responses compared; the ballistic limit and energy absorbed were also determined. The results indicate that the ballistic performance of the Ti/HB50 system is superior to the Ti/CFRP combination, in terms of ballistic limit and energy absorption. However, this difference diminishes when the impact velocity exceeds 1.5 times the ballistic limit. The rolling direction of the titanium sheet plays a significant role in the amount of energy absorbed, through its influence on the deformation/failure mode of the FMLs.

When subjected to wear by metal surfaces, epoxy normally exhibits rather high frictional coefficients (COF), causing high wear rate, exacerbated noise and frictional heat, thus limiting their service life. Liquid lubricants are known to reduce friction effectively, but they can be easily lost in operation. Therefore, encapsulating them is a proper solution to this issue. Herein, tribological properties of epoxy composites filled with wax-containing microcapsules (WMCs) and/or silica nanoparticles were investigated systematically. Results exhibited a tremendous decrease in the specific wear rates (Ws) and COF for the silica/WMC/epoxy ternary nanocomposites, specially three orders of magnitude reduction in Ws and a 10-fold reduction in COF were observed in specific test conditions. The wear mechanism was investigated based on worn surfaces and transfer films developed during wear tests. Furthermore, incorporating hybrid fillers negligibly deteriorates the mechanical properties of epoxy. Hence, the combination of rigid nanoparticles with WMCs is an appropriate choice when excellent tribological and mechanical properties are required.

Healing is a vital factor of polymer materials. Herein, an investigation on the healing performance of Graphene-CNTs reinforced thermoplastic polyurethane (TPU) composites induced by microwave was carried out. The results show that the graphene sheet and CNTs formed a combined structure of Graphene-CNTs. This Graphene-CNTs may have a synergy effect on the coupling between microwave and Graphene-CNTs on the interface, and promote the fully healing of damaged composites. The tensile strength of the healed composites even exceeds the value of the virgin specimens. Simultaneously, there is a microwave focusing effect within the region of crack, and on the surfaces of graphene or CNTs that exposed on the fracture surfaces. This effect will also promote the healing of damaged composites, and can realize the preferential healing of crack as compared with the non-damaged regions. These results may help us to get a deeper understanding of healing mechanisms of some thermoplastic composites.

Encapsulated phase change materials (EPCM) are the most common way to integrate with thermal systems for energy storage applications. Encapsulation greatly alters the thermal response of phase change materials (PCM) in terms of phase change temperatures and thermal hysteresis. Existing numerical schemes; however, can only simulate bulk PCM behavior and ignore the influence of encapsulation on the thermal response of EPCM. In this study, novel computational fluid dynamics (CFD)-based conduction dominant numerical schemes are developed for the first time to model the thermal response of EPCM and validated with the experimental DSC curve of the in-house fabricated EPCM capsules. The proposed heat source/sink scheme successfully predicts the heat-temperature responses and liquid volume fraction of EPCM with thermal hysteresis. It is recommended that the CFD-based conduction dominant heat source/sink scheme developed for EPCM in current study should be incorporated into energy simulation softwares for accurate performance predication when EPCM capsules are expected to be used in thermal energy storage systems and applications.

The interfaces between the composite and metal in fiber metal laminates (FMLs) are vulnerable to the attacks of moisture and heat. Two surface treatment methods are introduced to improve the interlaminar performance of the FML made of titanium alloy (Ti) and carbon fiber-reinforced polymer (CFRP). The FML prepared using the anodized Ti plate and CF sheets grafted with multiwalled carbon nanotubes shows significantly increased interlaminar fracture toughness (1382%), compared with the FML fabricated with sandblasted Ti plate and untreated CF sheets. The exposure to long-term hygrothermal environment, i.e. 60-day immersion in simulated seawater at room temperature, reduces the performance of both treated and untreated FMLs. However, the treated maintains the improvement of interlaminar performance, and shows much higher interlaminar fracture toughness (25.5 times) than the untreated. This study provides a feasible solution to tune the interlaminar properties of the FMLs based on titanium alloy and carbon fibers for industrial applications.

The dynamic failures of flat and single-curved woven basalt/epoxy laminates subject to blast loading were investigated experimentally. Number of fiber layers ((0/90) 9 , (0/90) 18 and (0/90) 28 ) and radii of curvature (infinity, R = 500 mm and R = 250 mm) were considered for the laminates in the experiment. A four-cable ballistic pendulum system was utilized to measure the impulse from the blast loading applied to the specimens. The tests were primarily conducted to characterize the deformation and failure modes of the laminates subject to blast loading, followed by a series of postmortem macroscopic and microscopic examinations to analyze the failure mechanism of laminates. The results showed that the blast-resistance of basalt/epoxy laminates was greatly enhanced through increasing the thickness. By decreasing the radius of curvature, the deformation mechanism of laminates under blast impact changed from flexural modes to indentation modes. Optical and scanning-electron (SEM) micrographs showed that the macroscopic delamination was mainly caused by matrix failure and debonding between fiber and matrix. Meanwhile, extensive fiber breakage led to the further macroscopic fracture of the laminates.

The Metal Composite Interface (MCI) properties affect not only the integrity of Fiber Metal Laminates (FMLs), but also the deformation/failure modes of FMLs. In this paper, the influence of MCI on the mechanical behaviors of Ti/CFRP/Ti laminates were experimentally investigated through indentation tests and low velocity impact tests. Three different surface treatments of titanium sheets were prepared to obtain the different MCI strength based on annealing, sandblasting, and anodizing. The treated surfaces of titanium sheets were analyzed using Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Spectrom (EDX). The MCI strength was characterized by apparent shear strength between titanium sheet and epoxy, which was measured through single lap shear test. The deformation/failure modes and energy absorption capacity of FMLs were analyzed. It was demonstrated that the MCI strength was greatly enhanced when the metal surfaces were sandblasted and anodized. The results showed that the improved MCI helped to maintain the integrity of FMLs under quasi-static and dynamic loadings. However, FMLs with higher MCI strength seemed to have weak resistance to damage and low energy absorption capacity.

Since there is a lack of modeling the effect of interfaces between hollow particles and matrix on the effective thermal conductivity of syntactic foams, a unit cell for the thermal analyses of syntactic foams in the presence of imperfect interfaces has been established. The model was validated with experimental data from literatures. The simulation results agree well with the experimental data. Based on the unit cell model, a parametric study was conducted to investigate the effect of interfacial thermal conductance, wall thickness and volume fraction of hollow particles on the thermal conductivity of syntactic foams. The results show that the thermal conductivity of syntactic foams increases with the increase of interfacial thermal conductance, wall thickness of hollow particles. However, the effect of volume fraction of hollow particles on the thermal conductivity of syntactic foams shows complicated dependence on the interfacial thermal conductance and wall thickness of hollow particles.

The planing trimaran possesses distinctive hybrid hydrodynamic and aerodynamic performance due to the presence of tunnel. The research described in this paper was carried out based on the observation of wave characteristics of a planing trimaran model in towing tests, in which the resistance drops as soon as the wave surface separates from tunnel roof. In order to gain a deeper insight into the relationship between wave flow and forces in tunnel region, a comprehensive series of viscous CFD simulations considering free-surface and 2-DOF motion of the hull (heave and pitch) have been performed for the tested model at the volume based Froude numbers ranging from 3.16 to 5.87. The calculated results were validated by comparison with experimental data and showed good agreement. Numerical results of wave contours, longitudinal wave cuts and lifting force distributions at the calculated speeds were presented for the analysis of ventilation process in tunnel region and the corresponding variation of tunnel forces. It is found that, for the speeds higher than Froude number of 4.52, the aerodynamic forces provide major tunnel lift and mainly act on the straight section of the tunnel. And, therefore, numerical simulations of two modified models have also been performed for the analysis of influence of straight section length on the hydrodynamic and aerodynamic performance of planing trimaran.

Unstable crack propagation behavior of carbon fiber reinforced plastic (CFRP) composites has a significant impact on the safety and reliability of structures in practical applications. Herein, we reported a method to improve the stability of crack growth by coating polydopamine (PDA) and graphene oxide (GO) on the surface of carbon fabric. The Mode I and Mode II tests were performed to study the delamination and crack behaviors of pure CFRP and modified CFRP. The crack propagation behavior can be tuned from unstable to stable manner without sacrificing the crack initiation during the opening mode test. It was revealed that the crack tended to fracture through the GO sheets, leading to the tearing and peeling of GO. The PDA&GO coated layers contributed to improving the load transfer between carbon fibers and polymer matrix, reducing the crack blunting degree, minimizing the unstable crack growth, and thus dissipating more energy. Keywords: Polydopamine, Graphene oxide, Carbon fiber reinforced plastic, Fracture toughness, Crack propagation

Electrically insulating phase change composite materials (PCCMs) with lightweight, good thermal management performance, high stability and high mechanical strength are strongly desired for lithium-ion battery (LIB) thermal management. This research study presents a group of PCCMs based on the integration of reduced graphene-oxide aerogel beads (rGOAB), phase change materials (PCMs) and thermally conductive silicone rubbers (SRs). To demonstrate the thermal management performance, a 3 × 3 square 18650 LIB module was inserted into a SR pack. The temperature reduction (temperature reduction of the battery cells at the hottest point in the SR pack compared with in air) reached 8.6 °C, 13.0 °C and 14.7 °C at 1C, 2C and 3C discharge rate, respectively, at a concentration of 20 wt% PCM beads in SR with thermal conductivity of 0.5 W/mK. The specific energy reduction of above-mentioned pack is only 15.8%, substantially lower than the commercial level (above 30% to 40%). The lowest specific energy reduction in SR pack with thermal conductivity of 0.3 W/mK goes down to 13.4%, indicating its remarkable lightweight and high energy density features. The effects of PCM-encapsulant type, SR matrix thermal conductivity and bead size on LIB temperature reduction were also discussed. The heat transfer mechanism between the matrixes and rGOAB/PCM was thoroughly explained. Mechanical properties and battery thermal management performance of the composites were systematically examined. The rGOAB/PCM@SR composites exhibited more than 10 times of impact strength compared with expanded graphite-based PCCMs and higher compressive toughness above the phase transition point.

Polyurea/poly(urea–formaldehyde)/Al2O3 hybrid microcapsules with a dense Al2O3 nano-layer containing 4,4′-methylenebis cyclohexyl isocyanate (HMDI) have been successfully fabricated via combaning Atomic layer deposition (ALD) process and interfacial/in-situ polymerization process. This dense Al2O3 nano-layer can be controllable deposited in the form of a single atom film through continuous self-limiting reactions of Al(CH3)3 and H2O on the surface of the PU/PUF microcapsules at a temperature range of 120–180 °C. The formed hybrid microcapsules showed a monodispersed diameter of ~60 µm with a controlled and nano-sized Al2O3 shell. Moreover, the deposited Al2O3 nano-shell significantly increased the thermal stability and mechanical property of hybrid microcapsules, which could maintain their integrity under harsh conditions. In addition, by embedding hybrid microcapsules into an epoxy matrix, an excellent anticorrosion performance in scratched coatings via self-healing functionality was obtained. Therefore, the formed hybrid microcapsules with enhanced thermal stability and mechanical property via ALD process could promote their practical application in self-healing composites.

This study investigates the effects of fiber type, resin type, and stacking sequence on the dynamic response of fiber-reinforced polymer composite (FRPC) laminates under low-velocity impact (LVI) tests. Novel thermoplastic (TP) laminates are fabricated with a newly developed liquid methyl methacrylate thermoplastic resin, Elium® 188, at room temperature. FRPCs comprising woven ultra-high molecular weight polyethylene (UHMWPE) fabrics, woven carbon fabrics, and two different hybrid systems with alternative stacking sequences of those fibers are fabricated by the vacuum-assisted resin infusion (VARI) method. Besides, equivalent thermosetting-based (TS) composites with two epoxy systems are fabricated to compare the role of matrix type. Impact tests at different energy levels are performed on the TP and TS laminates to investigate the impact characteristics, namely contact force, deflection, energy attributes, structural integrity, and failure/damage modes. Besides, the mechanics of structure genome (MSG) and the commercial finite element code ABAQUS are used to verify the experimental results for one of the developed laminates. The results demonstrate that the hybrid system with UHMWPE fibers on the sides exhibits lower structural loss up to 47% and lower absorbed energy by 18% compared to those presented by the other type of hybrid system comprising carbon fabrics on the sides. Besides, it is found that the newly developed TP laminate underwent extended plasticity and presented a ductile behavior. The newly developed TP laminate demonstrated lower structural loss up to 200%, lower contact force by 14%, and lower absorbed energy by 48% compared to those of TS counterparts.

Reducing filler content in microwave-absorbing composites is of great significance and challenging. Via a facile dip-coating method followed by a pyrolysis process, a new type of melamine foam (MF) derived carbon aerogel with in situ grown nitrogen-doped carbon nanotubes was fabricated, without using any externally introduced carbon source. Owing to the formed hierarchical and cellular structures, the prepared composites impregnated with epoxy (MF@GMC/epoxy) exhibit excellent microwave-absorption performance at a low filler ratio. The minimum reflection loss of a 3 mm MF@GMC/epoxy sample reaches −47.5 dB at 12.20 GHz. The effective absorption bandwidth achieves 6.72 GHz (9.22–15.94 GHz) while the filler loading is only 1.3 wt%. The development of MF@GMC/epoxy may pave a new avenue for the high-efficiency microwave absorption materials with extra-low filler loading.

This paper analyzes the spatial–temporal evolution of the attractiveness of a country’s gateway for its international trade, using Shanghai as an example. The attractiveness is regressed on the transportation facilities and geographical conditions. Seaport development is found to have a major positive impact, followed by inland waterway, highway, and airport development. These positive impacts decrease with the need for highway haulage and with the distance from Shanghai—showing an inverse U-shape distribution. Rail appears to have a U-shape distribution, implying a low application of multimodal transportation. A geographical pattern for the impacts of different transportation modes is delineated.

While traditional port literature uses origin and destination pairs in global shipping networks, recent developments of dry ports in the hinterland, feeder service networks, and heavy foreign trade traffic make the ports in Bohai Bay a unique case in the analysis of inter-port connectivity and competitiveness. Using an integrated port connectivity index to define the above features, the advantages and challenges of individual ports can be assessed in a dynamic interconnected environment. The model can provide unbiased port development strategies for each port to ensure long-term sustainability.

Dispersion systems such as solutions, suspensions and composites are frequently studied in the field of graphene and two-dimensional materials. The rapid development of these materials demands comprehensive insight into their dispersion systems. Here we present an innovative and systematic investigation on the dispersion systems of graphene-like two-dimensional materials. It is found that different dispersion systems exhibit similar fundamental laws which can be described based on a Most Probable Percolation Threshold (MPPT) theory. Two-dimensional sheets contact with their neighboring ones at around their MPPT concentrations and thus lead to sudden changes in various properties of dispersion systems, such as liquid crystal behavior, viscosity, mechanical strength, electrical conductivity and thermal properties. Starting from the MPPT theory, six new strategic guidelines for the engineering of dispersion systems are established. Based on these studies, we find that, appropriate size, appropriate thickness, and appropriate concentration, are the keys to the success of 2dMs dispersion systems in practical applications, and the MPPT theory could tell where it is appropriate. These investigations provide new theories, methodologies and guidelines for the science, engineering and developments of graphene and two-dimensional materials.