Highly Sensitive Weaving Sensor of Hybrid Graphene Nanoribbons and Carbon Nanotubes for Enhanced Pressure Sensing Function

Carbon nanotubes (CNTs) hold great promise in next-generation sensors because of their remarkable physical properties. Yet, maintaining precise stacking configurations of CNTs to make full use of their remarkable properties is challenging because of their susceptibility to spontaneous reconstruction. Inspired by the weaving technology, we propose a CNT-graphene nanoribbon hybrid woven model that can maintain the specific structure of CNTs to achieve their elaborately designed function. In this study, comprehensive molecular dynamics simulations are carried out to investigate the thermal stability of the CNT-graphene hybrid woven model, as well as their potential for pressure sensing applications by utilizing the unique response of thermal transport to mechanical deformation at heterojunctions. The thermal stability is sensitive to the size of the graphene nanoribbon, and the woven structure remains stable from 200-500 K when its width is greater than 2.0 nm. Moreover, it is exciting that the sensors are effective at predicting the shapes of externally loaded objects through the analysis of the thermal conductivity distribution, which can be derived from the relationship between the thermal conduction and the pressure. Our findings shed light on the bottom-up functional design of nanomaterials and expand wider applications of high-performance nanosensors in other related fields.

Phase Change Microcapsule Composite Material with Intelligent Thermoregulation Function for Infrared Camouflage

The infrared camouflage textile materials with soft and wear-resistant properties can effectively reduce the possibility of soldiers and military equipment being exposed to infrared detectors. In this paper, the infrared camouflage textile composites with intelligent temperature adjustment ability were prepared by different methods, using phase change microcapsule as the main raw material and high polymer polyurethane as the matrix, combining the two factors of temperature control and emissivity reduction. It was tested by differential scanning calorimeter, temperature change tester, infrared emissivity tester, and infrared imager. The results show that the temperature regulation effect of textile materials finished by coating method is better than dip rolling method, the temperature regulation ability and presentation effect are the best when the microcapsule content is 27%. When the bottom layer of infrared camouflage textile composite is 27% phase change microcapsule and the surface layer is 20% copper powder, its infrared emissivity in the band of 2-22 μm is 0.656, and the rate of heating and cooling is obviously slowed down. It has excellent heat storage and temperature regulation function, which can reduce the skin surface temperature by more than 6 °C and effectively reduce the infrared radiation. This study can provide reference for laboratory preparation and industrial production of infrared camouflage composite material. The infrared camouflage textile composite prepared are expected to be used in the field of military textiles.

Preparation of CF/PEEK Composites with High Mechanical Performance Using PEEK Derivatives as the Sizing Agent

Owing to their excellent physical and chemical properties, the carbon fibre reinforced poly(ether-ether-ketone) composites (CF/PEEK) are widely used in aerospace applications such as rockets, missiles, and high-speed vehicles. However, both carbon fibre (CF) and poly(ether-ether-ketone) (PEEK) have inert molecular chain structures, which seriously affect the interfacial properties of CF/PEEK composites. In this study, to improve the properties of CF/PEEK composites, carboxylated PEEK (PEEK-COOH) with different carboxylation degrees is synthesized as the sizing agent by a "two-step" method. Then, the activated CF surface is coated by PEEK-COOH sizing layers with different functionalization degrees to prepare the CF/PEEK composites. The results show that the interfacial properties of CF/PEEK composites are improved after applying the sizing agent. When the carboxylation degree of PEEK-COOH is 19.61%, the flexural strength, flexural modulus, and interlaminar shear strength (ILSS) of CF/PEEK composites reach 489.34 MPa, 25.387 GPa, and 81.3 MPa, respectively. In addition, the use of PEEK-COOH sizing agents can form an excellent transition layer between CF and PEEK, creating an efficient stress transfer system and facilitating an even stress distribution between CF and PEEK. Furthermore, the main mechanism of material fracture changes from CF debonding to CF and resin fracture.

Design of microperforated nanofibrous membrane coated nonwoven structure for acoustic applications

In this paper, a promising acoustic structure for noise reduction was prepared, in which microperforated nanofibrous resonant membrane together with nonwovens were used. The role of microperforated nanofibrous film, the effect of perforation parameters, cavity and the assembly sequence of the composite fibrous structure on sound absorption performance has been studied. This structure effectively combined the porous sound absorbing, micro-perforated absorbing and membrane resonance mechanisms, which can improve the sound absorbing performance without weight and thickness penalty offering a competitive advantage in noise reduction. In addition, the composite materials exhibited favorable performance in a wide-frequency regime under the condition of appropriate assembly sequence and perforation parameters.

Effect of Core Architecture on Charpy Impact and Compression Properties of Tufted Sandwich Structural Composites

This study presents a novel sandwich structure that replaces the polypropylene (PP) foam core with a carbon fiber non-woven material in the tufting process and the liquid resin infusion (LRI) process. An experimental investigation was conducted into the flatwise compression properties and Charpy impact resistance of sandwich composites. The obtained results validate an enhancement to the mechanical properties due to the non-woven core and tufting yarns. Compared to samples with a pure foam core and samples without tufting threads, the compressive strength increased by 45% and 86%, respectively. The sample with a non-woven layer and tufting yarns had the highest Charpy absorbed energy (23.85 Kj/m2), which is approximately 66% higher than the samples without a non-woven layer and 90% higher than the samples without tufting yarns. Due to the buckling of the resin cylinders in the Z-direction that occurred in all of the different sandwich samples during the compression test, the classical buckling theory was adopted to analyze the differences between the results. The specific properties of the weight gains are discussed in this paper. The results show that the core layers have a negative effect on impact resistance. Nevertheless, the addition of tufting yarns presents an obvious benefit to all of the specific properties.

Electrostatic Self-Assembly of Composite Nanofiber Yarn

Electrospinning polymer fibers is a well-understood process primarily resulting in random mats or single strands. More recent systems and methods have produced nanofiber yarns (NFY) for ease of use in textiles. This paper presents a method of NFY manufacture using a simplified dry electrospinning system to produce self-assembling functional NFY capable of conducting electrical charge. The polymer is a mixture of cellulose nanocrystals (CNC), polyvinyl acrylate (PVA) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). When treated with ethylene glycol (EG) to enhance conductivity, fibers touching the collector plate align to the applied electrostatic field and grow by twisting additional nanofiber polymers injected by the jet into the NFY bundle. The longer the electrospinning continues, the longer and more uniformly twisted the NFY becomes. This process has the added benefit of reducing the electric field required for NFY production from >2.43 kV cm⁻¹ to 1.875 kV cm⁻¹.

Finite Element Study on the Impact Resistance of Laminated and Textile Composites

The impact resistance of fiber-reinforced polymer composites is a critical concern for structure design in aerospace applications. In this work, experiments were conducted to evaluate the impact performance of four types of composite panels, using a gas-gun test system. Computational efficient finite element models were developed to model the high-speed ballistic impact behavior of laminate and textile composites. The models were first validated by comparing the critical impact threshold and the failure patterns against experimental results. The damage progression and energy evolution behavior were combined to analyze the impact failure process of the composite panels. Numerical parametric studies were designed to investigate the sensitivity of impact resistance against impact attitude, including impact deflection angles and projectile deflection angles, which provide a comprehensive understanding of the damage tolerance of the composite panels. The numerical results elaborate the different impact resistances for laminate and textile composites and their different sensitivities to deflection angles.

Effect of Panel Construction on the Ballistic Performance of Multiply 3D through-the-Thickness Angle-Interlock fabrIc Reinforced Composites

This paper studied the ballistic performance of 3D woven angle-interlock fabric reinforced composites with different types of panel construction. Two types of composites P10B and P17C were designed to have the same areal density of around 12 kg/m² although they both had different ply areal densities and consisted of different numbers of plies. Non-perforated ballistic impacts were conducted on the two types of panels under the same level of impact energy. Post-mortem examination on the non-perforated panels was conducted through the cross-sectional images, planar projected delamination and 3D damage volume extracted from the non-destructive tests. Three distinctive sections of damage were segmented from the non-perforated panels, each indicating different material failure modes upon impact. Under the same areal density, the coarser composite panel P10B with a larger ply areal density and fewer reinforcement plies would result in less damage. The damage volume of P10B is nearly one-third that of the P17C. The findings are instructive for the design of 3D woven fabric continuously reinforced composites with doubly-curved shapes.