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With the widespread application of carbon fiber reinforced polymer (CFRP) in engineering, the characteristics of uniformly carbon fiber (CF) orientation within a single-ply and laminated structure have inspired us to develop high-efficiency, low-consumption, manufacture-friendly, and non-destructive anti-icing/de-icing methods. Here, we propose a CFRP surface ply-centric electrified spatiotemporal self-heating (STSH) approach, which utilizes CFs in the surface ply as natural heating elements to achieve in-situ adaptable electrothermal anti-icing/de-icing. By adjusting the current waveform, the temporal heating profile can flexibly switch between a consistently stable temperature and periodically high peak temperatures, meeting the different heating characteristics required for anti-icing and de-icing, respectively. Simultaneously, the entangled CFs branch current, generating a spatial temperature gradient that enhances the design flexibility of temperature distribution. This enables energy concentration in icing-prone areas while maintaining a baseline temperature in less susceptible areas, thus reducing energy waste by up to 20%. Overall, this STSH approach is simple, efficient, and holds significant application potential, offering an innovative and feasible solution to long-standing challenges associated with anti-icing/de-icing. [Display omitted] • Simple and efficient solution to CFRP icing problems in extreme environments. • Without altering the manufacturing process and incurring additional costs. • With no introduction of heterogeneous elements, preserving mechanical integrity. • Imparts anti-icing/de-icing capabilities requiring only minor sanding. [ABSTRACT FROM AUTHOR]

The development of multifunctional electromagnetic interference (EMI) shielding materials has garnered significant attention, yet achieving flexible composites that integrate EMI shielding, thermal conductivity, and other functionalities under low filler loading remains a challenge. This study presents a novel flexible composite with segregated structure prepared via a simple co-mixing and hot-pressing method. By selectively distributing conductive Liquid metal (LM) and Multi-wall carbon nanotube (CNT) on the surface of Polyurethane (TPU) particles, a continuous and compact conductive network is successfully constructed, enabling the attainment of a high EMI shielding effectiveness of 80.2 dB and a thermal conductivity of 4.8 W m−1 K−1 even at low LM loadings. Furthermore, the composite exhibits low-voltage-driven Joule heating performance, excellent photothermal conversion efficiency, and promising potential for wearable sensor applications. The combination of these outstanding properties highlights the great potential of LM-based composites for next-generation wearable devices. Multifunctional TLMC composites that integrate EMI shielding, thermal conduction, strain sensing, and photothermal conversion properties. [Display omitted] • TLMC flexible composite with segregated LM/CNT structure. • Remarkable photothermal and electrical-to-thermal conversion capabilities. • Excellent conductivity (100.2 S/cm) and superior EMI SE (up to 80.2 dB). • Strain sensing application capable of monitoring wearable motion. [ABSTRACT FROM AUTHOR]

Of large length-to-diameter ratio and specific area, inorganic whiskers were widely applied for polymer reinforcement. As a well-known nanofiller, titanium dioxide (TiO 2) has been welcome by polymer engineering, mostly for whitening with spherical shapes favored. To date, there have been no TiO 2 whiskers reported for polymer reinforcement. In this work, a rutile type TiO 2 whisker was compounded with polyamide 66 (PA66) to prepare nanocomposites with surficial modification being conducted to further improve the compatibility between them. It was found that the rutile-type TiO 2 whisker significantly improves the mechanical properties of PA66 at high loadings and the performance went better when surficial modification for it was applied. Under 50 wt% addition of TiO 2 whisker either modified or not, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and heat deformation temperature of prepared PA66 composites were respectively increased by 52 %, 279 %, 44 %, 313 %, 20 %, 199 % and 84 %, 279 %, 88 %, 303 %, 114 %, 207 %, comparing with the pristine PA66. The mechanism regarding the overall reinforcement was analyzed, which was attributed to the shape-relevant multiple interactions between TiO 2 and PA66. Besides, the improved adhesion due to strong stable chemical bonding by surficial modification of fillers, is also accountable. [Display omitted] [ABSTRACT FROM AUTHOR]

There is an urgent need for developing "low-carbon" synthesis technology to prepare aerogel composites with both high mechanical strength and efficient thermal insulation for applications of modern aerospace and energy saving. Herein, we propose a strategy for fabricating lightweight phenolic aerogel composites with thick-united connected nano-structure and good aerogel-fiber interfacial compatibility. The specific micro-nano structure and optimized material synergism endow the aerogel composites with an ultrahigh tensile strength (12.84 ± 0.64 MPa), bending strength (24.69 ± 1.96 MPa) and compressive strength (1.7 ± 0.053 MPa under 5 % strain), as well as low thermal conductivity (0.0541 ± 0.0003 W/(m·K)). The aerogel composites behave excellent ablation-resistance under the flame of 1200 °C within 30 min and maintain a cold-side temperature of 56.07 °C without any shape change. The rigid-flexible comminated aerogel composites open up a new technical track for developing lightweight thermal protective composites with high strength, toughness, and efficient thermal insulation demanded in extreme environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphite composite insulation boards (GCIB) have emerged as a promising solution in the construction industry, offering a combination of fire resistance, high temperature stability, and excellent insulation properties. As their usage continues to increase, it is crucial to develop and validate a more accurate theoretical model for the effective design and optimization of building insulation systems. Traditional models including series and parallel models are employed for estimating the thermal conductivity of GCIB but revealed higher relative errors and lower theoretical calculation accuracy. Therefore, the primary objective is to design and validate a more efficient theoretical model for thermal conductivity prediction in GCIB. This paper investigates the thermal conductivity of GCIB under varying composition ratios by designing a novel Parallel-Series Parallel (PSP) approach. The PSP model is designed based on a single basic cell where the graphite polystyrene particles are employed as the matrix material while cement, vitrified microspheres, and silica fume are used as inclusion materials. Then, the thermal conductivity unit is divided into three parallel heat conduction subunits where the matrix materials and inclusion materials in the three subunits are integrated in a series-parallel manner to provide a more realistic representation of the heat transfer mechanisms within the composite. For a comprehensive assessment, the study encompasses theoretical analysis, empirical assessment, and finite element (FE) simulations to illustrate its thermal properties. The predicted thermal conductivity reveals perfect consensus in comparison with the FE and experimental test outcomes by achieving lower relative errors of 2.7 % ∼ 3.8 % and 1.9 % ∼ 3.0 % respectively. The model validated through numerical simulations and sample experiments illustrates a significant improvement in accuracy of about 76.4 %∼94.3 % when compared to traditional series and parallel methods. Prominently, the findings indicate that the thermal conductivity of GCIBs declines considerably as the volumetric ratio of graphite polystyrene particles (Ф 1 /Ф 3) increases and stabilizes when the proportion reaches 10, emphasizing the importance of optimizing material composition to enhance the thermal performance of GCIB. Overall, the validated PSP model by accurately determining the thermal conductivity of GCIB serves as a reliable tool for designing and optimizing high-performance insulation materials, contributing to energy efficiency and sustainability in building and construction industries. [Display omitted] • Developed Parallel-Series Parallel (PSP) model for GCIB thermal conductivity prediction. • PSP model integrates matrix and inclusion materials in a realistic heat transfer representation. • Achieved lower relative errors (2.7%–3.8 %) compared to FE and experimental tests. • Demonstrated 76.4%–94.3 % accuracy improvement over traditional series/parallel models. • Optimal thermal performance achieved with higher graphite polystyrene particle ratios. [ABSTRACT FROM AUTHOR]

In this study, a bio-based polyarylene ether ketone (bio-PAEK) was synthesized to prepare water-based sizing agents for enhancing the interfacial adhesion between carbon fiber (CF) and matrix. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results indicated that the bio-PAEK exhibited good thermal properties. To improve the processability and reduce the processing temperature, PAEK with a low melting point (LMPAEK) was also used as the matrix resin. The glass-transition temperature (T g) of LMPAEK was slightly higher than that of polyether ether ketone (PEEK), but its melting temperature (T m) was lower 48.5 °C. A strong interface was created after introducing sizing agents onto the CF surface due to good compatibility between fibers and matrix. The interlaminar shear strength (ILSS), interfacial shear strength (IFSS) and flexural strength of CF2/LMPAEK composites increased by 54.7 %, 56.0 % and 46.6 %, respectively, compared with the untreated composites. This study provided a novel approach to prepare water-based bio-PAEK sizing agents for CF composites with a low melting point matrix to be applied in additive manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

With the development of high-density electronics, polymer-based thermal conductive composites with excellent thermal and mechanical performance are receiving great attention. For the development of polymer-based thermal conductive composites with superior properties, it is essential to reduce the agglomeration of fillers and enhance the interfacial interactions between thermal conductive fillers and the polymer matrix. Among the several thermal conductive materials, graphene nanoplatelets (GNPs) and cellulose nanofiber (CNFs) are attracting attention. However, poor interfacial interaction between GNP and CNF leads to interfacial separation, which in turn, deteriorates its properties. Herein, we synthesized a pyranine-functionalized polyether dispersant (PyPE), which can significantly improve the interfacial interactions between GNPs and CNFs. The effect of PyPE on the dispersion behavior of GNPs and the thermomechanical properties of GNP-CNF composite were monitored. Furthermore, we also performed molecular dynamics (MD) simulations to investigate the impact of applying PyPE dispersant on the interfacial interactions between the GNPs and CNF matrix. The application of PyPE significantly enhanced the dispersibility of GNPs within the CNF matrix, resulting in a 15.5 % increase in-plane thermal diffusivity and a 24.5 % enhancement in tensile strength of the composite, demonstrating their potential applications in high power density electrical equipment and electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficiently thermal management in electronic devices calls for creating polymer composites that have superior thermal transport abilities. Compared with single-filler composites, hybrid-filler composites have gained significant attention as they not only utilize the advantages of each filler individually but also allow for the potential cooperation in constructing filler networks between them. Differing from the previous research on hybrid-filler size, geometry, composition, and content and their impact on thermal conductivity (TC) in composites, this study aims to examine the spatial distribution effects of hybrid-fillers. A binary-filler strategy comprising of anisotropic 2D h- BN and 0D isotropic S–Al 2 O 3 has been proposed, with the primary h -BN filler aligned to filly utilize its anisotropy and intrinsic TC properties. Furthermore, positioning a small quantity of S–Al 2 O 3 between adjacent parallel h -BN considerably improves TC in the non-oriented direction of silicon rubber (SiR) composites. A special focus is given to the influence of the interstitial S–Al 2 O 3 filler on the individual through-plane TC (λ ⊥) and in-plane TC (λ ⫽) variation of the binary-filler hybrid SiR composites, which are perpendicular and parallel to the oriented h -BN. When incorporating 40 vol% h -BN and 5 vol% S–Al 2 O 3 , the binary SiR composites exhibit the highest concurrent λ ⫽ and λ ⊥ values of 14.581 and 2.132 W/m·K, respectively. The corresponding effects on the ductility, hardness, and dielectric properties of the SiR composites were explained. Moreover, the use of commercially available TC fillers, along with the effortless preparation method, enables the potential to produce h -BN based TIMs materials on a large scale for thermal management usage. [Display omitted] • A binary filler system consisting in-plane oriented 2D h -BN and 0D isotropic S–Al 2 O 3 is designed. • The addition of S–Al 2 O 3 filler between adjacent parallel h -BN flakes facilitates vertical heat transfer. • The binary structure of h -BN/S–Al 2 O 3 exhibits an anisotropic feature in the filler contact thermal resistances. • The binary filler strategy mitigates the trade-off between in-plane and through-plane thermal conductivity. [ABSTRACT FROM AUTHOR]

This study focuses on enhancing thermal properties of aramid copolymer nanocomposites by integrating hexagonal boron nitride (hBN). Pristine hBN (P -hBN) is first subjected to oxidative heat treatment at 900 °C, producing thermally treated hBN (T-hBN), which significantly improves thermal conductivity while also increasing the tensile properties of composites. The study further explores the effect of different diamine co-monomers, 3,4′- and 4,4′-oxydianiline (ODA), on the nanocomposite properties. Both types of ODA-based composite films show improvement in various properties containing T-hBN. With 20 wt% of T-hBN, the 3,4′-ODA and 4,4′-ODA-based films exhibit 33.2 % and 290 % increase in tensile strength and thermal conductivity, respectively. The functionalization of hBN by heat treatment enhances the interaction between aramid copolymer and hBN and prevents the aggregation of hBN. The rough interface was shown in fractured images for films with T-hBN, suggesting that the composite films with T-hBN withstand higher external forces. In addition, it was observed that T-hBN exhibits better dispersion compared to P -hBN. This is supported by molecular dynamics (MD) simulation, and, in addition, it also provides the underlying mechanism for the property differences between both types of co-monomers. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs) are vital to dissipate excess heat generated by electronic components with ever-growing power density to ensure their reliability and performance. However, the limited dispersibility of nano-sized thermal conductive fillers hinders further enhancement of thermal conductivity in TIMs. It remains challenging to manufacture high-performance TIMs with simultaneous high thermal conductivity, low cost, and capability of large-scale production. Herein, a solvent-free and scalable approach was adopted to fabricate asphalt/graphite nanoplatelets (GNPs) composites by in situ exfoliating graphite in asphalt melt using a three-roll mill. During exfoliation, asphalt was adsorbed onto the surface of GNPs via π-π interaction and improved their dispersibility. Hence, GNPs formed integrated thermal conductive pathways with reduced interfacial thermal resistance, which significantly improved the thermal conductivity of asphalt/GNP composites. At 25 vol% loading, the asphalt/GNP composite displayed a thermal conductivity of 1.95 W m−1 K−1, showing a 114 % increase compared to the asphalt/commercial GNP (c-GNP) composite prepared by conventional mechanical mixing. Moreover, the heat-resistant and mechanical properties of the asphalt/GNP composites were also enhanced due to the improved filler dispersion and filler-matrix interactions. Thus, the asphalt/GNP composites fabricated by in situ three-roll milling possessed remarkable advantages as TIMs compared with asphalt/c-GNP composites and commercial silicone rubber thermal pads. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer laminates' weak interlaminar properties limit application in high load-bearing structural components. Interleaving electrospun polymer veils or nanofillers between layers has been shown to improve laminate interlaminar fracture toughness (ILFT). In this work, we constructed a "core-sheath" reinforced veil based on a bionic principle inspired by the "tree-root system" by combining ZnO nanowires with electrospun nanofibres to achieve uniform nanocomponent distribution and directional modulation. The effect of "core" structures with different thermal properties and "sheath" structures with different dimensions on the mode I and mode II interlaminar fracture toughness were investigated. It was found that mode I and mode II ILFTs impose different requirements on the interlaminar reinforcement structure due to the different loading modes. The intact nanofiber morphology and longer ZnO nanowires are more advantageous for mode I ILFT. Mode II ILFT, however, is more dependent on the adhesion of the reinforcing veil to the matrix. Mode I and mode II ILFTs values increased by up to 75.6 % and 118 %, respectively, when enhanced with suitable reinforcement veils. "Core-sheath" structures of various heat-resistant grades were constructed, enabling uniform distribution and orientation regulation of nanoparticles. The interlaminar mechanical properties of the laminates were improved and functionalization potential was given. Reinforcement mechanisms were mainly analyzed to provide new ideas for the design of laminated laminates with interlaminar reinforcement structures. [Display omitted] [ABSTRACT FROM AUTHOR]

With the advancement of semiconductor technology, advanced electronic devices have become increasingly efficient, highly integrated and multifunctional, producing a large amount of heat during operation, thus decreasing the device efficiency and increasing the requirements for thermal interface materials. The use of a magnetic field to prepare pitch-based carbon fibers (CFs) with ultrahigh axial thermal conductivities and aspect ratios is a promising method for preparing thermal interface materials. However, past methods are not adequately simple or effective. Herein, we propose a simple, efficient method for preparing a novel thermally conductive CF interface material with a superoriented and closely arranged structure. The thermal conductivity of the vertical plane can reach 82.026 W m-1 K-1, which is higher than that of many other alloys. During the experiment, we prove that the torsional vibration of the vibrating plate can greatly resolve the issue of powder bridging generated during preparation. In addition, we discover and explain the heat return conduction phenomenon through numerical simulation. Our innovative preparation process and our analysis of thermal conduction can provide a new method and unique view for the design of thermal interface materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Modern integrated electronics are in great demand for high-performance electromagnetic interference (EMI) shielding materials with exceptional mechanical properties. Liquid metal (LM) has demonstrated great potential in EMI shielding by its superior electrical conductivity. However, its real-world EMI application is limited by the poor compatibility, insulating oxide shells, and unpredictable leakage. Here, graphene oxide (GO) is used to encapsulate LM to form LM@GO microdroplets dispersion, and bacterial cellulose (BC) is applied to construct a biocompatible fabric network. Moreover, GO is in-situ reduced by hydrazine vapor, which generates synergistic LM/reduced graphene oxide (rGO) conductive pathways with the aid of roll-in process, obtaining flexible LM/rGO/BC (LGB) composite film with outstanding electrical conductivity of 4.5 × 104 S/m and exceptional shielding effectiveness of 64.0 dB. The rGO sheets and BC network demonstrate layered structure after roll-in process, effectively impeding the leakage and oxidation of LM and achieving a tensile strength up to 62.9 MPa of LGB films. Meanwhile, the LGB films exhibit exceptional Joule heating performance, and the stable surface temperature reaches 110 °C with high stability and reliability when the applied voltage is 4 V. This work provides a feasible engineering approach to prepare LM-based films for applications in EMI shielding and wearable electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

To develop thermal interface materials with both high thermal conductivity and electromagnetic interference shielding, the polyvinylidene fluoride (PVDF) composite film was prepared by electrospinning and hot-pressing, using strategies of multi-layered structure and two fillers synergy of nickel modified carbon nanotube (Ni-CNT) and Al 2 O 3 microspheres. The composite film consisted of a Ni-CNT filled PVDF electrospun fiber film as the top and bottom surface layers, and a PVDF electrospun fiber film electrostatically adsorbing Al 2 O 3 microspheres and surface-sprayed with Ni-CNT as the middle layer. At a 20 wt% Ni-CNT in the surface layers and a 16.7 wt% Al 2 O 3 and 5 wt% Ni-CNT in the middle layer, the composite film with a thickness of 0.1 mm exhibited optimal performances with electromagnetic wave shielding efficiency of 65 dB in the frequency range of 8.2–12.4 GHz, with 86% of the electromagnetic waves being absorbed. At the same time, the composite film had a high in-plane thermal conductivity of 4.02 W m−1 K−1, while maintaining a tensile strength of 25 MPa and flexibility. Using strategies of multi-layered structure and two fillers synergy of nickel modified carbon nanotube (Ni-CNT) and Al 2 O 3 microspheres, the as-prepared composite film with a thickness of 0.1 mm exhibited total electromagnetic wave shielding efficiency (SE T) of 65 dB and electromagnetic wave absorption efficiency (SE A) of 56 dB in the frequency range of 8.2–12.4 GHz, and a high in-plane thermal conductivity of 4.02 W m−1 K−1. [Display omitted] [ABSTRACT FROM AUTHOR]

Passive daytime radiative cooling (PDRC) is an efficient strategy to achieve cooling through spectrally selective emission and high solar spectrum reflection. Current preparation strategies for PDRC materials mainly involve doping inorganic micro-nanoparticles into polymers, but their solar reflectance is usually insufficient. Here, we designed a super-white inorganic coating on different substrates based on natural halloysite nanotubes (HNTs) through the doctor blade method. Polyvinyl alcohol (PVA) and water-based acrylic resin (AR) were introduced to increase the adhesion for obtaining robust inorganic coating. HNTs/PVA/AR composite coating shows excellent water resistance, wear resistance, and environmental tolerance, which is mainly due to the strong interfacial interactions between HNTs, PVA, and AR. Compared with the uncoated transparent plastic, the coated plastic exhibits a super-white appearance (whiteness of ∼95%) and maximum solar reflectance of ∼97%. The maximum temperature difference of the HNTs/PVA/AR coated and pristine copper sheet is 15 °C under simulated sunlight. The PDRC property is related to the high surface roughness of the coating composed of disordered high-aspect ratio nanotubes and the high whiteness of the raw halloysite materials. The composite coating can tolerate pH from 1–13, temperature change (−60∼250 °C), and different salt environments. The composite coating increases thermal stability, flame retardancy, and giving protective effect of dye against UV degradation. In addition, the HNTs/PVA/AR coated plastic as packaging materials can maintain good freshness of different fruits under strong solar irradiation. The robust HNTs/PVA/AR composite coating with high PDRC properties shows promising application in food packaging, building energy conservation, metal anticorrosive coating, and sunscreen products. [Display omitted] • HNTs/PVA/AR composite coating was prepared by the doctor-blade method. • The coated plastic exhibited an ultra-white appearance (whiteness ∼95%). • Composite coating offered UV resistance and high solar reflectivity (∼97%). • The composite coating had excellent wear, water, and environmental resistance. • The composite material showed a good effect on maintaining the freshness of fruits. [ABSTRACT FROM AUTHOR]

The determination of the thermoelastic properties of polyimide (PI) fibers is important for their applications, however, these properties are difficult to measure directly, especially the transverse thermoelastic properties. Here, the transverse thermoelastic properties of PI fibers, including transverse Young's modulus (2.12 GPa), shear modulus (0.94 GPa), Poisson's ratio (0.05), and coefficient of thermal expansion (45.68 μm/m°C), were estimated by combining dynamic and static thermo-mechanical techniques, as well as various relevant micromechanical models. The transverse Young's modulus of PI fibers was only 1/46th of the longitudinal one, and the transverse coefficient of thermal expansion of PI fibers was positive, unlike the longitudinal one, which was negative, showing the typical anisotropy of PI fibers. Finally, the thermoelastic properties of the PI fibers were in turn used to predict the thermoelastic behavior of the PI fiber-reinforced composites, thus validating their effectiveness. [Display omitted] [ABSTRACT FROM AUTHOR]

Rubbers combine the flexibility with mechanical strength, supporting myriad applications, but suffer from inherent flammability. Formulation and production of flame-retardant rubber composites (FRRCs) have intensively been practiced over years, but not comprehensively reviewed. This necessity has outlined collecting, analyzing, screening, classifying, and interpreting the literature with the aim of classifying the FRRCs. We quantified and visualized the flame retardancy of natural and synthetic FRRCs by grouping FRRCs based on their flame retardants (FRs) among green, mineral, phosphorus-based, nitrogen-based, carbonaceous, and hybrids of two or more types. Available data on cone calorimetry, limited oxygen index (LOI), and UL-94 of FRRCs were carefully extracted and plotted. Flame Retardancy Index (FRI) was used to specify the Poor , Good , or Excellent classes of flame retardancy in association with the chemistry and concentration of FRs to broaden the future innovation avenues. Machine Learning (ML) modeling enabled visualization of flame retardancy landscapes of natural and synthetic rubbers in terms of the chemistry and concentration of FRs. Overall, a downward trend in mechanical properties of FRRCSs against FRs amount was oxplored. This study proposed a general guideline for recognizing gaps in previous investigations and mechanistic interpretations. In conclusion, we highlight that the future FRRCs should take advantage of hybridizing FRs in order to meet the fire safety requirements, which would be possible by the innovative colorful checkered flame retardancy chart presented in this survey. [Display omitted] • Reviewed and classified flame-retardant natural and synthetic rubber composites (FRRCs). • Visualized the effect of chemistry of rubbers and flame retardants (type, amount and number). • Took chemical fingerprint of FRRCs by Machine Learning (ML) and discussed mechanistically. • Proposed an inventory map to systematically select the flame retardants for rubber composites. [ABSTRACT FROM AUTHOR]

Polyimide (PI) has been extensively used in 5G microelectronics however the relatively high dielectric constant (∼3.5) and moisture adsorption have greatly limit its practical applications in high-frequency region. Here hydrophobic PI/SiO 2 composite films with low dielectric constant and excellent thermal stability were synthesized by dispersing methyl modified hollow silica nanospheres (MHS) into polyamic acid solution prior to imidization treatment. Comparing with unmodified hollow silica nanospheres (HS), the MHS obtained through methyl modification can disperse uniformly in the PI matrix. Thus, the relaxation and orientation polarization of the PI chains as well as their electron migration are suppressed, resulting in a significant decrease in dielectric constant. The PI/MHS-10% film exhibits a stable low dielectric constant (1.9–2.3) in the high-frequency range (8.2 GHz–12.4 GHz), meanwhile maintains a high breakdown voltage (192 kV/mm), mechanical properties (64 MPa) and an excellent thermal stability (T d5% = 546.5 °C; T max = 589.0 °C). Moreover. PI/MHS demonstrates much lower linear expansion coefficient of 25.0 ppm/K that better matches the substrate. The surface contact angle of PI/MHS increases from 73° to 110° and the water absorption rate decreases from 3.1% to 1.6%, effectively avoiding the moisture adsorption. This work provides a simple method to prepare high-performance composite films for 5G practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The study contributes to the understanding of potassium hexatitanate whisker (PHW) reinforced EPDM composites with superior ablation resistance, which can facilitate the development of high-performance EHSMs for advanced spacecraft. To achieve this, ablative materials with varying PHW content were prepared, and their thermal stability and ablation characteristics were analyzed using thermogravimetric analysis, oxyacetylene ablation test, scanning electron microscope, and other analytical methods. The study unveiled the internal mechanism through which PHW enhances the ablation performance of ablative materials by reducing thermal conductivity and forming carbon fixation centers. Furthermore, micro-morphology analysis revealed that ablative materials containing PHW exhibit a denser surface char layer, thereby enhancing its resistance against erosion. Additionally, the pyrolysis mechanism of EPDM and the formation process of amorphous carbon on TiO 2 surface were simulated using molecular dynamics. [Display omitted] [ABSTRACT FROM AUTHOR]

The prediction of the prevailing self-heat transfer parameters of a glass/epoxy composite coupon during fatigue testing in general and the distinction between viscoelastic- and frictional crack growth-related energy dissipation in particular, are not trivial problems. This work investigates the feasibility of predicting the convective film coefficient, the total work loss as well as the ratio between viscoelastic and fracture-induced damping from thermal images using Bayesian optimization in conjunction with 3D FE thermal analysis. To this end, glass fiber/epoxy biax coupons are pre-damaged by means of a drop weight impact machine and subsequently tested under uniaxial tension-tension high cycle fatigue conditions. IR images are taken of the self-heating thermal profile at steady-state conditions. Synthetic surface thermal images are generated by numerical thermal analysis of the damage distribution obtained by μ -CT scanning prior to testing. Bayesian optimization of the aforementioned parameters is conducted by minimizing the loss function between the as-measured and the synthetic IR image. The predicted work-loss is consequently validated against the measured hysteretic response, from which a very good agreement is found. [Display omitted] • Thermal heat transfer parameters are predicted via Bayesian optimization (BO). • FEM and BO are combined to find physically meaningful parameters. • The method efficiently handles 3D parameters compared to other approaches. [ABSTRACT FROM AUTHOR]

Drawing inspiration from the robustness and resilience of spider silk, this study harnessed a combination of polydopamine (PDA), cellulose nanofibers (CNFs), polyvinyl alcohol (PVA), and aminated carbon nanotubes (CNTs) to create a synergistic network through hydrogen and covalent bonding on the surface of carbon fibers (CFs). This strategy significantly bolstered the interfacial properties of the resulting composites. The enhancements in flexural strength, flexural modulus, interlaminar shear strength (ILSS), tensile strength, and interfacial shear strength (IFSS) were measured at 47.8 %, 75.2 %, 54.3 %, 55.6 %, and 51.8 %, respectively. These improvements are attributed to the formation of robust covalent and hydrogen bonds among PDA, CNF, PVA, and aminated CNTs. Furthermore, the thermal conductivity of the CF composites saw a 59.7 % increase, owing to the CNFs and CNTs. These nanofillers are instrumental in forming an efficient thermal conductivity pathway within the resin matrix, which contributes to the improved thermal conductivity. This study introduces a straightforward, eco-friendly, and innovative approach for the production of high-performance CF composites. [Display omitted] [ABSTRACT FROM AUTHOR]

This work reported a novel preparation of waxberry-like calcined alumina/poly diallyldimethylammonium chloride/diamond (AO*@ND) via a facile self-assembly of cationic polymer, electrostatic adsorption of nano-sized diamonds and calcination process. The incorporation of hybrid particles into an epoxy matrix significantly enhanced the thermal conductivity and dielectric properties. For example, the thermal conductivity of epoxy composite with 10 wt% calcined AO*@ND in air at 500 °C soars to a remarkable level of 0.70 W/(m·K) and 1.83 W/(m·K) at room temperature and 100 °C, respectively. In addition, its dielectric breakdown strength was 59.6 kV/mm, only showing a decrease of 11 % compared to that of epoxy. More importantly, the epoxy composites with the calcined AO*@ND showed an ultralow dielectric loss. The modification strategy of hybrid filler provides a new insight on the development of thermally conductive yet electrically insulating materials for future power modules and electrical equipment. The epoxy matrix composites with high thermal conductivity and sufficient dielectric breakdown strength were prepared via introduced a calcined AO*@ND filler to utilize the small size effect of nano-sized diamond and the forming lattice structure between alumina and diamond. [Display omitted] [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanosheets, such as graphene and hexagonal boron nitride, are considered as the most promising fillers for enhancing thermal conductivity of polymers and phase-change materials. Nevertheless, the effect of various 2D nanosheets on the effective thermal conductivity of composites is not fully understood, and the corresponding prediction model is still lacking, since numerous influence factors and complex thermal transfer networks are involved. This paper aims to study the macroscopically effective thermal conductivity of the nanosheets-reinforced composites in a systematical way, and develop a robust machine learning based prediction model. To this end, a series of representative volume elements are reconstructed based on the SEM observations of experimental samples, and high-throughput simulations are performed via the updated lattice Boltzmann scheme proposed in our recent work. The effects of shape, size, orientation, intrinsic thermal conductivity, interface thermal resistance, surface coating, and hybrid filling of the 2D nanosheets are clarified. This work could provide a deep insight into the effective thermal conductivity of the nanosheets-reinforced composites, and may offer important guidelines for the custom-design of polymer and phase-change composites with targeted thermal performances. [Display omitted] [ABSTRACT FROM AUTHOR]

In view of the diversified demands for thermal management materials in soaring developments of electrical systems, the high thermally conductive composites often suffer from their poor mechanical properties and electrical insulation. Targeting at enhancing simultaneous thermal conductivity, dielectric and mechanical properties, the fibers reinforced gradient structured polyethylene-based composites consisting of ultrahigh molecular weight polyethylene (UHMWPE) fiber layer and hybrid-filled layer are proposed and successfully prepared by simple overlapping-hot pressing. The fibers collaborated with gradient arrangement of hybrid-filled layer in modulating the temperature, electric and stress field distribution. The resultant as-designed composites exhibit excellent thermal conductivity of 0.91 W/(m·K), ultrahigh tensile strength of 104.7 MPa and superior breakdown strength of 161.5 kV/mm, which are increased by 18%, 1374% and 37% than those of the homogeneous composites, respectively. This work provides a new strategy for manufacturing high-performance polymer-based composites. [Display omitted] • A new strategy was proposed to design PE-based composites with high thermal-dielectric-mechanical performances. • The UHMWPE fibers reinforced gradient structure was constructed through simple overlapping-hot pressing. • The structured composites have ultrahigh tensile strength, superior breakdown strength and high thermal conductivity. • The fibers collaborated with hybrid-filled layer in modulating the temperature, electric and stress field distribution. [ABSTRACT FROM AUTHOR]

The demand for biopolymer-based green packaging has attracted growing attention because of its outstanding properties and consistency with clean environmental principle, unfortunately, its slow crystallization rate and narrow processing window are challenging. Inspired by combined functions in nanocellulose-based conductive hybrids, this work developed high-performance polylactic acid (PLA) composites using conductive cellulose nanofiber (CNFene). Interestingly, CNFene has multiple functions as highly graphitized carbon and abundant hydroxyl groups, delivering stimulating properties to PLA composites. As nucleating agents, 3 wt% CNFene has a carbon layer on the surface combined with a hydrogen bonding network synergistically enhancing the tensile and crystallization properties of PLA-C3, with a tensile strength of ∼ 53.7 MPa, crystallinity of ∼ 33.9 %, and 6.6 °C decrease in the cold crystallization temperature. Additionally, the compatibility between CNFene and PLA can form a multi-level "reinforcement" network structure, further improving thermal stability and barrier properties. The resultant PLA-C3 showed higher thermal decomposition onset temperature (T 0), wider melt-processing window (197.6 °C) and extremely lower overall migration levels in ethanol (68.6 μg/kg) and isooctane (16.3 μg/kg), due to that improved interaction between CNFene and PLA positively affects crystallization ability and kinetic/mechanism of PLA to meet the requirements of industrial and green biopackaging applications. [Display omitted] [ABSTRACT FROM AUTHOR]

For polymer foams, a high expansion rate is often required to obtain a low thermal conductivity. However, polymer foams with high expansion ratio faces a difficulty of shape recovery. In this work, polystyrene (PS)/polymethyl methacrylate (PMMA)/carbon nanotubes (CNTs) composite foams were prepared by the synergy of ultrasound and H 2 O in supercritical carbon dioxide (scCO 2) foaming. The introduction of ultrasound and H 2 O is beneficial to improving expansion ratio. CNTs can enhance the melt strength of PS/PMMA, which also absorb part of the thermal radiation. Therefore, the PS/PMMA/CNTs foams with 0.5 wt% CNTs exhibits the high expansion ratio (80.7 times), low thermal conductivity (25.98 mW/mK) and 100% compression recovery in water at 85 °C after one compression. In addition, with the increasing of filler contents, the reusability of the foam is further improved. After ten compressions, the PS/PMMA/CNTs foams with 2 wt% CNTs still achieve the 99% recovery. This work provides a new way to prepare polymer foams with super-insulation and reusability. [Display omitted] [ABSTRACT FROM AUTHOR]

Needle-punched fabric reinforced nanoporous phenolic composite (NPC) is a kind of promising ablative thermal protection material for spaceflight. However, in practical applications, typically anisotropic microstructure of NPC may lead to different performances and damage mechanisms under various directional mechanical or thermal loads. Herein, NPC is prepared and cut into specimens along three typical plane directions including XY -plane (0°), Z -plane (90°), and transitional-plane (45°), and their mechanical, thermal insulation, and ablation behaviors are systematically investigated. Benefiting from the woven fabric in XY -plane, NPC in 0°-plane direction exhibits highest tensile strength (169.2 ± 12.6 MPa), and CT image-based simulation further verifies that woven fabrics are primary load-bearing structure. Meanwhile, NPC in 45°-plane direction shows highest compressive strength (443.1 ± 18.2 MPa) but low compressive stress at low strain, demonstrating a weak bonding between two layers of woven fabrics. Moreover, the heat transfer simulation indicates that horizontally stacked woven fabrics effectively protect the internal material from thermal erosion, thus NPC in 0°-plane direction exhibits optimal thermal insulation. The ablation testing and micro-CT observations further demonstrate that the angle between woven fabric and thermal load significantly influences the ablation mechanism. The present work will further promote the structural reliability and optimization of needle-punched composites. [Display omitted] [ABSTRACT FROM AUTHOR]