1,721,011 research outputs found
Studio dell’organizzazione morfologica delle fasi amorfe in sistemi polipropilene-polietilene a composizione variabile.
No full textCertification challenge for self-responsive materials in aeronautics
No full textInnovation and continuous development of cutting-edge materials find robust interest of companies for using avantgarde technologies. Material research is widening toward mainly two directions: the improvement of the existing functionalities and the development of new functionalities of the materials. However, widespread applicability of materials with new functionalities and their marketing requires also efforts towards the creation and implementation of technical standards and measurement techniques. Standardization is an important stage in the development of any new material and it is based on the consensus of stakeholders including end users, businesses, standards organizations and governments.
The main function of standards is to define the qualities and technical properties of a material to ensure consistency across different manufacturers and industries. It is important to assure that a product is genuine, safe and will perform in the way it is expected. For new materials standardization will also enable easier communication between producers and consumers.
In this context, the current paper shows the activities performed within MASTRO Project – H2020, focusing on the possible strategies to reach the standardization of innovative materials in aeronautic field. In MASTRO Project self-healing, de-icing, self-sensing and self-curing materials, obtained using nanocomposite technologies, have been widely studied and tested to understand their usability in a significant environment. The purpose of the standardization activity in MASTRO project is to explore the possibility of transferring the results of research into one or more standards. The first step is to understand the research results which have not necessarily a need to be transposed into standards, and those that potentially will provide valuable support to new or existing standards through, for example, the validation of test methods or product and /or process.
The second part of this activity was the identification of needs and opportunities for standardization in the eventuality partners have developed specific procedure or protocol to overcome particular issues, which were not reported in literature. Generally, in this process the applicability of the possible standard to other bodies (research groups both academic and from industries) was considered. The use of some innovative functionalities developed in MASTRO project, such as those related to self-healing materials, has not been yet regulated with any of the available standards. For these materials, standardization need and opportunities have been identified in order to enable their widespread use. The preparation of a New Work Item Proposal on this kind of functionalities (with all relevant documentation that can help for the procedure) is in progress.
Figure 1 shows the followed approach and the applied strategy to rationalize data regarding available standard, standard needs and opportunities of the developed materials for the evaluation of possible Standardization Processes. The used algorithm for the rationalization of the information is based on the readiness level of the technology and on the relevance to improve the safety of the material
Solvent induced ordering phenomena in a segmented chain mesogenic polymer with a flexible substituent at the rigid moiety.
No full textJ. MACROMOL. SCI. PHYS
Damping assessment of new multifunctional epoxy resin for aerospace structures
No full textThe increasing demand for more advanced materials, particularly in the aerospace field, has led to the development of carbon-fiber-reinforced composite manufactured employing different kinds of nanoparticles. The reinforcement with Carbon Nanotubes (CNTs) allows the modulation of several characteristics of the composite, which becomes suitable for more extreme operating conditions. Furthermore, the incorporation of CNTs in polymeric matrices of composite materials allows them to be electrically conductive, and hence suitable for developing self-responsive/self-protective materials characterized by a combination of properties strongly requested for replacing the traditional composites. In addition, detection of specific electrical properties can be used to develop self health-monitor composites subjected to damages due to static and dynamic loads. For instance, damage detection through conductivity measurements offers many advantages when compared to traditional glass fiber optic sensors. In fact, because of their high cost, it is not possible to create a dense network of these fibers to inspect large parts of the composite and especially if the damage spreads in the material without crossing the fiber. Therefore, the use of carbon nanotubes may provide an effective solution to overcome the described limitation. As part of an intensive research activity aimed at studying the performance of innovative smart resins, in this article, the authors show the outcomes related to some of the dynamic properties of the developed resins. Relevant results related to the enhancement of dissipative phenomena have been found in formulation modified with elastomeric phase e CNTs
DYNAMIC PERFORMANCE OF A NANO-MODIFIED COMPOSITE AERONAUTICAL PANEL
No full textThe adoption of composite materials is becoming increasingly attractive in many aeronautical applications. The improved endurance and corrosion resistance are few of the advantages they can offer, compared to the conventional alloy solutions. Due to the extraordinary mechanical property of carbon nanotubes (CNTs), they can be considered as an effective reinforcement treatment for composites. Multifunctional materials are designed so as to meet specific requirements through tailored properties. These materials, employed both for general aviation and very light class, allow to be readily modified with extra upgrading treatments during the lay-up manufacturing phase, thanks to their physical constitution. Particularly, in aerospace applications, the potential implementations of these advanced materials have been predicted to have a large impact on future aircraft vehicles, mainly due to their distinct features, which include greater mechanical, thermal and electrical characteristics. In such framework, different vibro-acoustic tests have been performed on a fiber-reinforced panel, representative of an aeronautical shell, for the characterization of the damping as well as the transmission loss properties related to such micro-handling treatment. The spectral excitation has been provided by an acoustic source, simulating in such a way the aerodynamic pressure load agent on the structure. Significant studies have been carried out to investigate and improve the vibro-acoustic properties of filled or reinforced polymer composites: the authors showed that the use of nano-particles such as CNTs can really improve the dynamic performance of standard laminates
Tuning The Interaction Between Carbon Nanoparticles And Epoxy Matrix For Improving Multi-Functionality Performance Of Structural Nanocomposites
No full textThe recent ability of material scientists in the control of matter behaviour at nanoscale level can be exploited to design a
new generation of emerging materials able to simultaneously satisfy several structural and functional requirements. Very
low content of electrical conductive nanoparticles embedded in epoxy resin, or introduced between-lamina interfaces, can
help for example to address limitations related to the electrical and thermal insulating properties which negatively impact
on the design of anti-lightning properties, anti-icing systems and thermal dissipation phenomena. Recent developments,
in the field of structural composites, highlight the relevant property of carbon nanoparticles in providing a very effective
strategy to fulfill industrial requirements related to the damping control. It is well known that vibrations must be
minimized by appropriate design features through active and/or passive damping treatments in order to improve aircraft
performance and reliability levels of structures and systems. Passive damping treatments in composites as a result of the
application of embedded viscoelastic materials (which possess an intrinsic capacity of dissipating mechanical energy)
reveal greater advantages in terms of energy efficiency and reliability of machines/structures compared to active systems.
Recent developments on nanotechnology have shown that the addiction of CNT in epoxy resins modify the stiffness and
damping properties as a consequence of variation of the epoxy 3D network structure. This phenomena, called damping
enhancement via stick-slip mechanism, is strictly related to the non-ability of the CNT to fully adhere to epoxy matrices
and to the load transfer from epoxy to nanotubes. A lack of adhesion and load transfer causes slippage of CNT which
results in enhanced damping characteristics. The work hereby described regards the design of multifunctional epoxy
mixtures, based on carbon nanoparticles, with enhanced damping features. Dynamical-mechanical analysis (DMA)
highlights that the inclusion of the nanofiller in the resin causes a variation in the phase composition of the epoxy matrix.
In particular, the impossibility to extend the tri-dimensional network in the space filled by the nanoparticles is
responsible of a more mobile phase responsible of a better behaviour in the damping performance. The effectiveness of
this strategy can be further improved by suitable control of the resin chemical composition. A deep control of
composition and interactions between carbon nanoparticles and matrix can provide an effective strategy to enhance the
damping performance of nanofilled composites
The influence of different dispersion methods on the size of the aggregate of CNTs in epoxy resin for the manufacturing of carbon fiber reinforced composites
No full textDifferent industrial mixing methods and some of their combinations (1) ultrasound; (2) stirring; (3) (4) by roller machine, (5) by gears machine (6) Ultrasound radiation + high stirring were investigated for incorporating Multi walled Carbon nanotubes (MWCNT) into a resin based on an aeronautical epoxy precursor, cured with 4,4′ diamine-dibenzylsulfone (DDS). The effect of different parameters, ultrasound intensity, number of cycles, type of blade, gears speed on the nanofiller dispersion were analyzed. The inclusion of the nanofiller in the resin causes a drastic increase in the viscosity, preventing the homogenization of the resin and a drastic increase in temperature in the zones closest to the ultrasound probe. To overcome these challenges, the application of high speed agitation simultaneously with the application of ultrasonic radiation was used. This allows on the one hand a homogeneous dispersion, on the other hand an improvement of the dissipation of heat generated by ultrasonic radiation. A comprehensive study with parameters like viscosity and temperature was performed. It is necessary a balance between viscosity and temperature. Viscosity must be low enough to facilitate the dispersion and homogenization of the nanofillers, whereas the temperature cannot be too high because of re-agglomeration
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