G. Rinaldi

CNT Composites for Aerospace Applications

Carbon nanotubes were synthesized by thermal arc plasma process after optimization of the synthesis parameters. These samples were then analysed by scanning and transmission electron microscopes (SEM and TEM), in order to establish the morphology of the nanostructures. Atomic force microscopy (AFM) and electron diffraction studies were also carried out before using the sample for the composite material preparation. Composites of epoxy resin with curing agent as well as a mixture of graphite and carbon nanotubes were prepared with varying proportions of the mixture. The electrical resistivity of the material was studied under varying pressure and voltage conditions. Preliminary results of these studies present interesting features which are reported here.

Mechanical and electrical characterization of epoxy nanocomposites for electromagnetic shielding devices in aerospace applications

Polymer-based composites are popular in electronic applications due to their light weight, low cost, high strength and easy processing. The major part of these is used to insulate electrical circuits against atmospheric agents uniquely. Many polymeric materials are transparent to electromagnetic radiation and provide no shielding against electromagnetic interference (EMI). In electronic and communication applications, the EMI pickups by electronic components give rise to serious problems, such as noise enhancement and malfunction of electronic instruments [1]. In order to avoid such drawbacks, the developing of materials with both typical composite and EMI shielding properties is thus required.

Electrical Properties and Electromagnetic Shielding Effectiveness of Carbon Based Epoxy Nanocomposites

Designing and engineering of new kind of electromagnetic interference (EMI) shielding for electronic systems and devices is a pressing need due to the wide range of using of several electronic devices. Electromagnetic (EM) shields have to guarantee high performances and right operation of electronic systems and to prevent the electronic pollution. Electronic systems are getting faster, smaller high frequency of clock and high energy in small dimension, so they generate, as effect, thermal drawback, and mechanical, as well. They are used in several electronic equipments and it is easy to find them in common life: communications, computations, automations, biomedical, military, space and other purposes. Nanocomposites based on Carbon Nanotubes (CNTs) give powerful and multifunctional materials with very high performances: mechanical, thermal, electrical properties. It is possible to achieve lighter and cheaper EM shields than the actual ones. Examples of new materials that can come from nanotubes are many: high conductors that are multifunctional (electrical and structural), highly anisotropic insulators and high-strength, porous ceramics and others.

Studies of Carbon Nanotube Based Composites for Aerospace Applications

Carbon nanotubes are being widely studied for various applications ranging from medical to electronics and also optical devices. They are also being studied for the suitability and applications in aerospace and aeronautical field. A useful application in aerospace that we are studying is the improvement of electrical properties of composites made from carbon nanotubes and epoxy resin. Towards this end, we have studied the resistivity of composite materials with varying percentages of carbon nanotubes (CNT) added to the epoxy resin. Carbon nanotubes were synthesized by thermal arc plasma process after optimization of the synthesis parameters. These samples were then analysed by electron microscopes like scanning electron and transmission electron microscopes (SEM and TEM), in order to establish the morphology of the nanostructures. Composites of epoxy resin with curing agent as well as a mixture of graphite and carbon nanotubes were prepared with varying proportions of the mixture. The electrical resistivity of the material was studied under varying pressure and voltage conditions. The result of these studies yields interesting features which are useful in choosing the ideal composition and ratio of the composite material for use in shielding of electrical circuits of space vehicles from radiations of the outer space.Copyright

Epoxy — Nano-carbon shielding coating for super-high-frequency range

Analysis on electromagnetic (EM) response properties of Modified Bisphenol A Epoxy Resin loaded with various types of commercial fillers, Multi-Wall CNTs (MWNTs), Single-Wall CNTs (SWNT), Carbon Black was made. The EM attenuation and reflection in Ka-band (26–37 GHz) provided by resin/SWCNT were measured as a function of the functional filler content (up to 1.5wt.%) and the EM coating thickness. A high THz attenuation ability is demonstrated in the range 0.2–3 THz by the CNT-based samples The transmission at 1 THz through the sample containing 0.5 wt.% of SWNT inclusions is 12 times less than through pure resin, and 3 times less in the case of MWNT incorporation. In the far-infrared frequency range (3–18 THz) a small reflection of the THz signal was observed (up to 5%) for all types of nanocarbon inclusions. The maximal reflection is demonstrated by the net epoxy resin, which denotes a strong screening effect of the given matrix. [1, 2].

ELECTRICAL PROPERTIES AND ELECTROMAGNETIC SHIELDING EFFECTIVENESS OF EPOXY/SWCNT COMPOSITES

The non-ohmic current-voltage (I-V) characteristics and the temperature dependence of the resistance of the epoxy/SWCNTs composites in the temperature range of 2-300 K were investigated. Their electrical properties can be described in the frame of a heterogeneous model for conduction. The transmission, reflection and absorption spectra were measured in Ka-band. The epoxy/SWCNTs composites demonstrate high electromagnetic shielding effectiveness: the average power transmitted through the samples is about 30 %.

Effectiveness of microwave electromagnetic shielding in carbon based epoxy nanocomposites

We report on the comparative study of the effectiveness of electromagnetic shielding provided by different forms of nanocarbon dispersed in resin.

Stabilizing action of polymeric plasticisers in PVC

Polymeric plasticisers gained considerable success in PVC formulations in the early eighties and there are now several manufacturers of plasticising additives based on polymeric compositions in the USA. The good performance of these additives has been considered in the technical literature. For epoxy polymeric plasticisers, an improvement of heat and U.V. stability was also observed as a function of the oxirane oxygen content in formulations. In this paper we refer to some experimental tests on thermal and U.V. light stabilising action of linear low molecular polyesters, based on glycols and dibasic aliphatic acids, which possess a good plasticising effect and low toxicity. Creep tests and calculations of isochronous creep modulii were used to evaluate the stability of PVC formulations.