Composites Communications最新文献

A convenient strategy for preparing meta-structures with a negative Poisson's ratio (NPR), which enhance mechanoelectrical responsiveness and are typically based on inner concave hollow cells, is 3D printing without support structures. However, this process requires the material to have high melt strength, often linked to high viscosity and low printability. In this work, we introduced 0D carbon black (CB) into a thermoplastic polyurethane (TPU)/1D carbon nanotubes (CNT) composite to create a dimension-hybrid filler system, enhancing strength with minimal viscosity increase. The results show that the bending modulus and Young's modulus of CB/CNT(1:3)/TPU composites are increased by 1.6 times and 1.8 times that of TPU, while its viscosity (2697.98 Pa⋅s) is lower than the allowed value of printer. Then, the 3D-printed suspension bridge of TPU is 42.7 % less saggy, significantly benefiting to preparing meta-structures. Based on a support-free 3D printable enclosed hollow structure, the TPU / CNT / CB composite material achieves an adjustable NPR between −0.59 and −0.20. Compared to unfolded structure, this NPR characteristic further improves the piezoelectric output voltage by 9.00 times, enhances the compressive modulus by 3.15 times, and improves the piezoresistive sensitivity by 122.0 %. Sensors based on this 3D-printed material showcase high performance stability and reproducibility, demonstrating their potential in wearable equipment.

The molding flow of carbon fiber reinforced thermoplastic sheet molding compounds (CFRTP-SMC) is complex and requires a comprehensive understanding of underlying processes. This study investigates the material behavior during compression molding processes, focusing on the influence of the ratio of initial material charge area over mold area (charge ratio) on mechanical properties. The results highlight the CFRTP-SMC material's excellent flowability and moldability and confirm that the mechanical properties and internal morphology change with charge ratios. In addition, a correlation between mechanical properties and internal morphology is established through quantitative analysis of fiber orientation distributions using X-ray computed tomography. This comprehensive investigation not only sheds light on the molding ‘behavior of CFRTP-SMCs, but also underscores the importance of material charge ratios in influencing the mechanical properties. This study also provides a case study for validating numerical process models.

To enhance the survivability of military aircraft in electromagnetic warfare, carbon fiber/nickel-iron layered double hydroxide (CF/NiFe-LDH) composites with heterogeneous structure were constructed starting from the raw industrial carbon fiber (CF) by electrostatic self-assembly. By reasonably adjusting the mass ratio of CF and NiFe-LDH, the voids formed by LDH arrays stacked on the fiber surface are utilized to promote reflection and scattering of electromagnetic wave (EMW), optimizing impedance matching, as well as synergize dielectric-magnetic dual loss mechanism. Moreover, interfacial polarization effect induced by the abundant heterogeneous interfaces significantly enhance the ability of EMW dissipation. The optimized CF/NiFe-LDH heterostructure composite exhibits the minimum reflection loss (RL_min) value of −52.48 dB at mere 1.77 mm thickness and an expansive maximum effective bandwidth (EAB_max) of 7.29 GHz at 2.14 mm. In addition, the computer simulation technology (CST) revealed that the radar scattering cross section (RCS) reduction of composites reaches up to 26.92 dBm² at an incidence angle of 90°, demonstrating their excellent radar attenuation capability. Tremendously, the heterogeneous composites achieve an SRL₁ value of 524.8, which is appreciably better than most of the EMW absorbing materials. The wondrous characteristics including lightweight, ultra-thin, high-efficient microwave absorbing ability of CF/NiFe-LDH heterostructure composites display potential application in fighter aircraft.

This paper discusses the improvement of roller compacted concrete by the addition of red pine needle (PN) fibers optimized by bioinspired techniques. The purpose was to determine a perfect set of mechanical characteristics, such as flexural, compressive, and splitting tensile strengths, by determining proper correlations between the water-cement ratio, superplasticizer, and fiber volume. Based on the data obtained with the help of experiments, it was shown that optimizing the PN fibers added to RCC with nature-inspired algorithms (particle swarm optimization, genetic algorithms, simulated annealing and artificial neural networks) yields positive results in terms of improving a number of characteristics, including flexural strength, fracture toughness, and durability. In addition, adopting PN fibers has certain environmental benefits. All methods under analysis showed good results, with the artificial neural network (ANN) being superior in terms of predicting the parameters of RCC. The discussed research confirms the effectiveness of such optimization methods for determining the best proportions for RCC using PN fibers. At the same time, future studies could further develop sustainable and mechanically strong RCC formulations.

Thermoelectric (TE) materials are crucial for the efficient conversion of thermal energy into electrical energy, with broad applications in harvesting waste or low-grade heat, localized cooling, sensing, and wearable electronics. To date, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most widely studied system in organic and composite TE materials. In this review, we focus on the latest advancements in the preparation, mechanisms and applications of PEDOT:PSS-based TE composite films. First, we provide an outline of the background and historical development of TE materials. Then, we systematically summarize the preparation techniques. After that, strategies for enhancing TE performance and the in-depth mechanism of structure-TE performance relation are discussed. Subsequently, we discuss the TE and mechanical properties. Finally, we emphasize the recent progress in applications of power generation, sensing, and wearable technologies. In the conclusion, we discuss the future outlook and the challenges.

The design of fully biological epoxy resin (EP) composites with high performance is highly desirable driven by green and sustainable development due to their renewable and sustainable nature. Herein, an efficient intumescent flame retardant based on Miscanthus floridulus (MF-based IFR) was devised for bio-epoxy composites by a green self-assembly method. The resulting composites with 15 wt% MF-based IFR demonstrated outstanding flame retardancy, effective smoke suppression, and favorable mechanical properties. The enhanced flame retardancy demonstrated the V-0 rating of UL-94 and the 26.4 % of limiting oxygen index (LOI) due to the dual-phase flame-retardant mechanism. Compared to pure EP, the EP composite with 15 wt% MF-based IFR exhibited reductions of 71.90 %, 61.85 %, 55.0 %, and 60.94 % in peak heat release rate (pHRR), total heat release rate (THR), smoke release rate (SPR), and smoke growth rate (TSP), respectively. Additionally, compared to unmodified MF, the composites with 15 wt% MF-based IFR displayed increasing of 3.35 %, 11.26 %, and 10.24 % in tensile, bending, and impact strengths, respectively, attributed to the enhanced interface compatibility. This study provides a straightforward, cost-effective, and efficient strategy for producing fully bio-based epoxy composites with high performance, expanding their potential applications.

This study investigated the influence of fluorinated graphite (FGi) on the thermal and mechanical attributes of epoxy/fluorinated graphite (EP/FGi) composites. The TGA analysis revealed that the temperature of 5 % weight loss (Td5) increased from 281.5 °C for EP to 364.0 °C for EP/2%FGi, the heat-resistance index (THRI) increased from 170.2 to 190.6. The composite exhibited a significant improvement in hardness at 1 wt% FGi content. The bending test results indicated that the addition of 2 wt% FGi to the EP increased the bending strength, modulus, and toughness of the samples by 35.2 %, 29.6 %, and 54.8 %, respectively. Analysis of the worn surface morphology indicated that composites with FGi exhibited reduced damage and a smoother surface compared to those without FGi. The superior heat capacity and heat transfer properties of FGi mitigated the build-up of frictional heat, and high hardness diminished cutting and fracture during friction, and the enhanced toughness provided by FGi delayed the generation of fatigue cracks during the friction process. The excellent thermal and mechanical properties of EP improved by FGi synergistically improved the tribological properties of the material.

Shape-memory polymers (SMPs) are smart materials that can recover their original shapes from temporary ones under external stimuli. In recent years, various types of shape-memory polymer composites (SMPCs) have emerged, which not only expand the functionality of SMPs but also enhance their mechanical properties. It is crucial for SMPs and their composites to talk about the relationship between materials, moulding techniques, and applications. SMPs and their composites can achieve responses under electrical, magnetic, optical, and other stimuli, allowing for selective responses. These materials can be combined with a variety of technologies in diverse forms for wider application in different fields. This paper briefly introduces the SMPs and their shape memory mechanism and discusses SMPCs according to the type of filler. We then describe SMPs and their composites with different driving modes, which can result in varied application scenarios. The use of 4D printing technology, electrospinning technology, and micro/nano-pattern technology in SMPs and their composites, as well as the applications of SMPs and their composites in biomedical, aerospace, electronics, robotics, optics, and other fields have been demonstrated. Thus, SMPs and their composites will continue to play important roles as smart materials.

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of conventional materials used for plastic processing tools, particularly related to thermal conductivity, significantly influence production efficiency, with the cooling time of moulded parts appearing as one of the key factors. Therefore, this study focuses on designing Steel-Cu composites with the aid of a numerical model of the composite's microstructure for enhancing their overall thermal properties. We present a novel procedure for designing such composites, which facilitates the identification of the optimal shape for the phases to improve overall thermal conductivity. We have developed a data-driven homogenization model to aid the optimization process and ensure time-efficient solutions. The data has been generated through numerical homogenization based on the finite element method. The proposed shape optimization procedure has been applied to determine the optimal shape of the Cu phase across various volume fractions. We found out that the optimal shape of the Cu phase is not constant but depends on its volume fraction. Emphasizing the practical utility of the proposed procedure, it is noteworthy that once the data-driven model is established, it enables a time-efficient optimization of the Cu phase shape for arbitrary volume fractions of phases. Consequently, this may expedite the decision-making process for material manufacturers.