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Lightweight, flexible and low-cost electromagnetic interference (EMI) shielding materials with high shielding effectiveness (SE) have attracted considerable attention for next-generation portable and wearable electronics. In this work, high performance polymer composite-based EMI shielding materials are fabricated by utilizing highly oriented graphite frameworks (HOGFs) constructed via a facile intercalation–expansion of commercially available graphite papers to offer a simple and efficient approach for large-scale production. The obtained highly oriented conductive HOGF/polydimethylsiloxane (HOGF/PDMS) composites exhibit a remarkable conductivity of 21 000 S m−1 and a super-high EMI shielding value of over 96 dB in the X-band (8.2 to 12.4 GHZ) due to the multiple internal reflections caused by the long-range ordered stacking of graphite sheets. In consideration of the excellent conductivity and high electromagnetic shielding performance, along with ease and economy of mass production, the HOGF/PDMS composites demonstrate promising potential for next-generation EMI shielding materials. [ABSTRACT FROM AUTHOR]

Highlights: Detailed summary of current trends in the advancement of flexible EMI shielding materials. The theoretical shielding mechanisms and the latest concept of "green shielding" index (gs) are outlined. Functional applications of flexible EMI shielding materials are introduced from thermal conductivity, hydrophobicity to transparency, sensing even multiple functions. Exclusive insights in challenges and future design strategies opportunities for flexible EMI shielding materials are provided. With rapid development of 5G communication technologies, electromagnetic interference (EMI) shielding for electronic devices has become an urgent demand in recent years, where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role. Meanwhile, the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications. Hitherto, a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed. In this review, we not only introduce the recent development of flexible EMI shielding materials, but also elaborate the EMI shielding mechanisms and the index for "green EMI shielding" performance. In addition, the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized. Finally, we propose several possible research directions for flexible EMI shielding materials in near future, which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials. [ABSTRACT FROM AUTHOR]

A coupled moving beam-pulley vibration model is established for a typical serpentine belt drive system with three pulleys. Both general and explicit expressions for the eigenvalue sensitivity to the structural parameters of system are derived by perturbation analysis. Then the rule of the first-order natural frequency changes with system structural parameters is studied with the eigenvalue sensitivity verified by finite difference method. [ABSTRACT FROM AUTHOR]

Optimization design of the structures and thicknesses of the sound packages is performed for automotive interior acoustic performance and lightweight characteristics. A SEA model of the car was created, and its interior noise of the automobile was predicted and validated at speed of 120 km/h. The contributions of some major subsystems to interior noise were calculated at 120 km/h. Both of major characteristic indices including interior SPL and total weight of sound packages are selected to evaluate automotive interior acoustic performance and lightweight characteristics, and four selected optimization parameters are structures and thicknesses of the sound package of firewall and front floor. The problem of multiple performance indices is simplified into single performance index by using grey relational grade. The optimal combination of sound package parameters is determined by employing grey relational analysis method. Furthermore, the validation tests show that the values of interior SPL and overall weight of sound packages decrease by 1.31% and 60.36%, respectively. Also, the comparison of the overall SPL for automotive interior noise experiments between original and optimized structures and thicknesses of the sound packages shows that automotive interior acoustic performance is obviously improved from 200 Hz to 10,000 Hz. Therefore, it is demonstrated that it is an effective way to deal with optimization problems by using the presented approach in this research. [ABSTRACT FROM AUTHOR]

Environmentally friendly thermal interface materials (TIMs) with bidirectional high thermal conductivities have aroused considerable interests for addressing the heat dissipation issue in integrated circuits. Although graphene-based TIMs exhibit excellent in-plane thermal conductive performance, their through-plane thermal conductivity is commonly less than 3 Wm−1K−1 owing to the vast interfacial phonon scattering, significantly limiting their practical applications. In this study, a strategy aimed at building TIMs with controllable heat transfer pathways both along the in-plane and through-plane directions is proposed by incorporating micron-diamonds (MDs) in graphene nanoplatelets/nanofibrillated cellulose (GNPs/NFC) composite film via a facile and green self-assembly method. The morphology of the obtained MDs@GNPs/NFC composite film can be precisely tailored from a hierarchical structure to a 3D solid foam-like structure to tailor heat transfer paths. By adjusting the loading and particle size of MDs, a through-plane thermal conductivity of 8.85 Wm−1K−1 was achieved accompanied with a simultaneously high in-plane thermal conductivity of 32.01 Wm−1K−1. The excellent bidirectional thermal conductive performance is integrated with high-efficiency Joule heating capability, outstanding nonflammability, as well as superior electromagnetic shielding performance, showing a promising future in advanced electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

With an excellent combination of high strength, lightweight, and thermal stability, carbon fiber-reinforced polymer (CFRP) composites are ideal for applications in various demanding fields. The global consumption of CFRP composites continues to increase, and it is estimated that approximately 3000 tonnes of CFRP waste are generated annually. Mostly, the CFRP composites can be classified into two categories: thermoset composites and thermoplastic composites. However, the recycling of industrial thermoset composites is a daunting challenge due to their highly cross-linked thermosetting polymer matrix. In this study, an innovative strategy was developed for recycling amine-cured CFRP composites with a binary alkali catalytic system of monoethanolamine containing 10 wt% potassium hydroxide under facile conditions. The degradation ratio of CFRP composites reached 98.82% after processing at 160 °C in 90 min. The surface of recovered carbon fibers (CFs), as observed by SEM and AFM, appeared smooth, and there was a slight increase in the surface wettability as tested by dynamic contact angle measurements. Furthermore, the use of XPS demonstrated some surface oxidation, while single fiber filament testing suggests a small decrease in the tensile strength of 6.5%. • A binary alkali solvent system of monoethanolamine containing 10 wt% potassium hydroxide successfully degraded amine-cured CFRP composites under facile condition. • The method had the recovery yield of CFRP composites reached up to 98.82% after processing at 160 ℃ in 90 min. • The recovered CFs were clean with approximately 93% of original tensile strength. • The recovered CFs had better surface wettability than that of virgin CFs. [ABSTRACT FROM AUTHOR]

By reference to GB 15742, horn acoustic tests on thirteen passenger cars of different types are conducted, and the suitable evaluation terms of horn sound quality are determined according to the characteristics of horn sound samples. A subjective evaluation program suiting to paired comparison method is developed, and a test of the subjective preference of horn sound is carried out on 22 participants with the reliability and consistency of test data analyzed. Finally, the main psychoacoustic objective parameters of each sample are calculated, and a preference evaluation model describing the correlation between subjective preference evaluations and psychoacoustic objective parameters is established with algorithms of linear correlation and multi linear regression. The results indicate that the subjective/objective preference model is nonlinear, and the sharpness and linear sound pressure level, in particular the former, are the key factors affecting the people's favor and acceptance of horn sound quality. [ABSTRACT FROM AUTHOR]