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Napoli, Italy

Branca C.,CNR Institute for Research on Combustion | Di Blasi C.,University of Naples Federico II | Galgano A.,CNR Institute for Research on Combustion | Milella E.,IMAST Scarl
Thermochimica Acta | Year: 2011

The oxidation behavior of a composite material (Cycom 977-2/Priform by Cytec), based on a toughened epoxy resin reinforced with carbon fibers, is studied in the kinetic regime and a mixed thermal-diffusive regime. Thermogravimetric measurements for the composite material and the two single components support the existence of three main reaction stages. The first is the oxidative decomposition of the resin taking place at temperatures between 496 and 730 K that can be described by a reaction with an activation energy of 82 kJ/mol. The second and third reaction stages correspond to the oxidation of the resin char, that terminates at about 850 K, and at higher temperatures the oxidation of the carbon fibers, described by global kinetics with activation energies of 105 and 184 kJ/mol, respectively. The thermal history of thick samples burning in a furnace depends on the heating temperature, in nitrogen, and/or the maximum temperature, in air, caused by the reaction exothermicity. After an inert heating stage, when maximum sample heating rates are achieved, the process dynamics again show the existence of three main reaction stages whose characteristic times and temperatures are determined. © 2011 Elsevier B.V. All rights reserved. Source


Toscano C.,Cira Italian Aerospace Research Center | Lenzi F.,IMAST Scarl
Civil-Comp Proceedings | Year: 2010

In this work, specific viscoelastic materials characterized by different complex modulus have been selected, embedded and co-cured into the graphite/epoxy structure composites in order to study the impact behaviour of the obtained structures. Therefore, an impact test campaign at the same energy has been performed on the embedded panels as well as on simple graphite/epoxy laminates. The effects of the impact have been examined via Non Destructive Testing (NDT) using the Ultrasound Pulse-Echo technique, and by optical microscopy analysis, then the results have been compared. The presented work allows to establish that the impact behaviour of graphite/epoxy laminates could be highly influenced by the presence of damping layers. In particular the damping layers seems to strongly limit the damaged area, effectively reducing the inter-lamina damage propagation. © Civil-Comp Press, 2010. Source


Iannone M.,Alenia Aermacchi | Esposito F.,Alenia Aermacchi | Cammarano A.,IMAST Scarl
AIP Conference Proceedings | Year: 2014

Blends obtained by mixing high temperature applications thermoplastics have been investigated. Namely the blends considered in this work are made by semi-crystalline thermoplastics PEEK with amorphous PEI. The final goal is to analyse the mechanical, chemical-physical and environmental resistance characteristics of these blends to evaluate their suitability as matrices of carbon reinforced composites for aeronautical structural applications. The first collected results are very promising. © 2014 AIP Publishing LLC. Source


Galgano A.,University of Naples Federico II | Di Blasi C.,University of Naples Federico II | Milella E.,IMAST Scarl
Polymer Degradation and Stability | Year: 2010

A sensitivity analysis to assumptions and input variables is carried out for a predictive model previously developed [1] for the fire response of a glass-fibre/polyester panel and a glass-fibre/polyester-Vermiculux sandwich. It is an unsteady, one-dimensional model using the porous medium approximation and a constant gas pressure with two-step, finite rate kinetics for the thermal decomposition and combustion of the polymeric resin, moisture evaporation described by an Arrhenius rate law, heat and mass transfer by convection, heat conduction and radiation described by effective thermal conductivities, variation of the volumetric fractions of the polymeric resin and the moisture with the conversion degree, effective specific heats, external heat transfer resistances and surface ablation. The strongest impact on the model predictions is exerted by the imposed external heat flux with variations on the characteristic process times between 49 and 774%. An important role in sample heating/conversion is also played by surface ablation and/or external heat transfer resistance with variations up to 30-72% or, when ablation is disregarded, with temperatures along the core layer well below those of the degrading skin. These are also significantly affected by surface heat losses, with the assumption of adiabatic bottom surface leading to heterogeneous ignition of the lower skin, and evaporation of moisture with variations in the characteristic times up to 35%. The model for the effective thermal conductivity of the fibre-reinforced skin (the Parallel, the Maxwell-Eucken and the Effective Medium Theory models versus the Series model) is also important resulting in characteristic time variations up to 35%. The absence of local thermal equilibrium between the condensed and the gas/vapour phase and the kinetic details of the polymer reactions are comparatively less important (maximum diminution in the characteristic times of 16%). Moreover, although over-pressures, modelled by the Darcy law, become quite high especially during the moisture evaporation stage (up to ten times the atmospheric value), their effects on the thermal response of the structure are completely negligible when structural changes are not modelled. Finally, a sensitivity analysis is also carried out to input parameters.© 2010 Elsevier Ltd. All rights reserved. Source


Volponi R.,Italian Aerospace Research Center | Spena P.,IMAST Scarl | De Nicola F.,Italian Aerospace Research Center | Grilli A.,IMAST Scarl
16th European Conference on Composite Materials, ECCM 2014 | Year: 2014

In this work piezo-resisitive proprieties epoxy resins charged with carbon nanotubes are been verified. An efficient solution to integrate nanocharged matrix into a carbon fiber composites are been developed, achieving a multiscale carbon fiber composite. Finally mechanical and health-monitoring capabilities of multiscale composites are been evaluated. Source

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