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This study attempts to investigate the thermal conductivity behavior of epoxy nanocomposites containing different types of nanofillers, such as 1-D Multiwall Carbon Nanotubes (MWCNTs) and 2-D predominant shape of Exfoliated Graphite nanoparticles (EG) at loading level from 0.25 to 3% wt. For all the analyzed epoxy nanocomposites calorimetric investigation shows that EG nanoparticles accelerate the curing process of the epoxy resin. Thermal conductivity measurements show that this acceleration is directly related to the better heat conduction obtained through the incorporation of EG in the epoxy matrix. The thermal conductivity of epoxy nanocomposites filled with EG, unlike of epoxy nanocomposites containing MWCNTs, increases significantly with increasing content of nanofiller. An increase in thermal conductivity of ~ 300% has been detected for a filler percentage of only 3%wt of EG. The application of Deng-Zheng micromechanical model has proven to be very effective in predicting analytically the thermal conductivity of the analyzed nanocomposites., INTRODUCTION In the last few years many researchers have focused their activities on the incorporation of nanosized fillers into the epoxy matrix in order to develop light-weight composites characterized by [...]

Polymer-matrix composites containing conductive nanoparticles are a potential means for achieving an appealing combination of multifunctional properties for their use as structural parts in the aerospace field. Carbon nanofibers (CNFs) have been being looked forward to as the next generation of new and avant-garde aircraft structures because they are exceptionally coveted competitor materials to replace traditional metal components for lightning strike protection. In this regard, nanocomposites at low concentration of CNFs ranging from 0.05% up to 2% by wt to impart electron conduction in tetrafunctional epoxy resin have been prepared and characterized. The aim of this work concerns the use of Tunneling AFM (TUNA) as revolutionary tool able to correlate the electrical current map with the correspondent local morphology of CNF/resins. TUNA technique has proven to play a leading role in the identification of current paths and electrical interconnections, even without altering the morphology with usual treatments employed to create electrical contacts to the ground. Summing up, the good electrical performance together with the high mechanical properties due to a conductive cross-linked network of CNFs inside the resin demonstrate a charming applicative potential for the formulated nanocomposites as structural materials capable to provide a safe conductive path on the exterior skin, preventing serious damage to the aircraft.

Functionalized multi-wall carbon nanotubes (MWCNTs) have been embedded in a rubber-toughened epoxy formulation in order to explore the possibility to impart an auto-repair function to the epoxy matrix. The nanofiller has been covalently functionalized with hydrogen bonding moieties able to act as donor and acceptor of hydrogen bondings. Healing efficiencies have been evaluated for nano charged epoxy formulations at a loading of 0.5% wt/wt of functionalized MWCNTs bearing barbituric acid and thymine-based ligands. For both the performed functionalizations, a self-healing efficiency higher than 50% has been found. Dynamic Mechanical Analysis (DMA) highlights that the inclusion of nanofiller increases the storage moduli. Furthermore, DMA analysis evidences the presence of a phase characterized by a greater mobility of the epoxy chains, which promotes the activation of self-healing mechanisms.

Epoxy nanocomposites fulfill tight and compelling industrial requirements in the field of structural material for aeronautical applications. In this paper the development and characterization of nanocomposites obtained by filling tetrafunctional epoxy resin (tetraglycidyl methylene dianiline cured with the aromatic diamine 4,4’-diaminodiphenylsulfone, named T20BD) with carbon nanofibers (CNF) is discussed. A filler amount ranging from 0.05% to 2%wt is considered. The DC volume conductivity and the dielectric characteristics (ϵ’) of the nanocomposites in the frequency range 100Hz-1MHz are analyzed and compared with those of the pure resin. Atomic force microscopy, mapping the local topography by means of tunneling effect, is used for recording the electrical percolation path for nanocomposites. In particular, the case 1.3wt% of CNF filled nanocomposites that exhibits a stable behavior of the conductivity in the full investigated frequency range, is here reported. The developed filled epoxy used in carbon fiber reinforced composites, shows enhanced electrical properties leading to better electromagnetic (EM) performances in EM coatings, EM shields and filters or radar absorber materials (RAMs).

Crystallinity and mechanical properties of blends with different amounts of semicrystalline poly(aryl/ether ether ketone) (PEEK) and amorphous poly(ether imide) (PEI) polymers have been studied. The blends, prepared by melt mixing, have been investigated by differential scanning calorimeter (DSC) to analyze the miscibility between the components and the final crystalline content. Moreover, for the 20/80 PEEK/PEI blend, crystallization in dynamic and isothermal conditions has been carefully investigated in order to find proper conditions for maximum development of crystallinity. Mechanical tests (static and dynamic) have been performed to evaluate the properties of the as-molded and crystallized blends and to compare them with those of crystalline PEEK and amorphous PEI neat resins. Finally, a few SEM observations have been performed to compare the fractured surface of the blend with those of the pure constituents., INTRODUCTION Significant progress has been made over the last several years in the development of advanced composites, especially for structural applications in aircraft. The majority of the work has focused [...]