Bidimensional nanomaterials, such as graphene, respond to the rising demand for electromagnetic interference (EMI) shielding materials, followed by the advancements in wireless technology and increased signal sensitivity in electronic devices, especially for the safety of aircraft and other structures. Lightweight nanocomposites reinforced with 2D carbonaceous nanofillers can replace metals thanks to their ability to attenuate electromagnetic waves and low susceptibility to corrosion. In this work, the EMI shielding properties in the X band (8–12 GHz) of high content graphene nanoplatelets (GNPs) nanocomposites have been investigated. Both the effect of filler content and the nanoarchitecture have been studied. For this purpose, two different configurations have been considered, compact and porous, varying the filler content (from 10 wt% to 90 wt%) and the thickness of the samples. Specifically, four different systems have been tested: thin (i) and thick (ii) compact laminates and thin (iii) and thick (iv) porous coatings. The morphology of the material significantly influences its electromagnetic response in terms of reflection and absorption capacity. Maximum effective absorption of 80% was found for disordered structures, while a maximum reflection of about 90% was found for system highly aligned structures.
Recently, biomimetic brick and mortar composites (B/M) are gathering great attention due to their outstanding properties. The use of graphene as bricks is expected to achieve good mechanical performances combined with remarkable thermal diffusivity making them optimal candidates for heat spread applications. Macroscopic composites (1 mm thick) have been manufactured at different filler content (up to 100% vol%) and their morphology have been investigated by scanning electron microscopy. Bending test have been carried out on samples for measuring the effect of the polymer amount on the composite. The thermal diffusivity has been investigated, both in plane and cross plane, by light flash analysis (LFA). Coupons showed a well aligned inner structure at each resin content, however the effective performances depends on the capability of stress transfer., 0 0 (201 MATEC Web of Conferences https://doi.org/10.
Achieving high mechanical performances in nanocomposites reinforced with lamellar fillers has been a great challenge in the last decade. Many efforts have been made to fabricate synthetic materials whose properties resemble those of the reinforcement. To achieve this, special architectures have been considered mimicking existing materials, such as nacre. However, achieving the desired performances is challenging since the mechanical response of the material is influenced by many factors, such as the filler content, the matrix molecular mobility and the compatibility between the two phases. Most importantly, the properties of a macroscopic bulk material strongly depend on the interaction at atomic levels and on their synergetic effect. In particular, the formation of highly-ordered brick-and-mortar structures depends on the interaction forces between the two phases. Consequently, poor mechanical performances of the material are associated with interface issues and low stress transfer from the matrix to the nanoparticles. Therefore, improvement of the interface at the chemical level enhances the mechanical response of the material. The purpose of this review is to give insight into the stress transfer mechanism in high filler content composites reinforced with 2D carbon nanoparticles and to describe the parameters that influence the efficiency of stress transfer and the strategies to improve it.
Although seismic isolation devices are effective in protecting structures during an earthquake, they are generally large, heavy, and expensive, making their application prohibitive for housing buildings. In the last few years, different strategies have been investigated to make seismic isolators cheaper and lighter for housing buildings in developing countries. Lower costs can be obtained at different scales: simplifying the installation process of devices, reducing energy consumption during manufacturing, and using recycled materials. Both weight and cost of isolators could be reduced by adopting flexible reinforcements in place of steel reinforcing plates, also allowing easier installation without bolted connections in unbounded configuration. Costs can be further reduced by replacing natural rubber with a recycled elastomer. It has been demonstrated that trying to give a second life to rubber is challenging, since devulcanization process, capable of breaking chemical bonds between rubber and sulphur, is highly polluting and requires high consumption of energy. In the present work, a recycled compound has been preliminary developed with mechanical properties not significantly lower than virgin rubber. Obtained parameters are satisfactory for use in unbounded isolators with flexible internal reinforcement where internal stresses are significantly reduced. In particular, a novel compound has been properly formulated in order to be lower cost in comparison to traditional one. Mechanical characterization of the material showed excellent properties including shear modulus and hardness similar to those of a soft rubber, even if a reduced ultimate deformation capacity is achieved. Furthermore, rubber adhesion with different fabrics has been investigated. Preliminary results are very promising and pave the way for the development of high-performance and low-cost rubber isolators.
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