JEC COMPOSITES MAGAZINE - Issue #62 - January/February 2011 - 43

Multiscale hybrid carbon reinforcement for polymeric-matrix composites
The role of reinforcements and their interface with the matrix is known to be crucial in determining the performance of a polymeric composite material. The mechanical properties of composites can be improved by enhancing the load transfer at the reinforcement/matrix interface, e.g. by tailoring the interfacial shear strength. A novel, multiscale hybrid reinforcement has been developed to this end. The reinforcement consists of microsized commercial carbon-fibre yarns and fabrics coated with carbon nanostructures. This type of hybrid reinforcement is expected to have great potential for polymeric-matrix composite applications, because it combines microscaled and nanoscaled materials.
vary fibres architectures, and consequently to tailor the composite’s mechanical properties, widens the spectrum of applications. The fibre-matrix interface plays an essential role in the performance of fibrous polymer composites. Good interfacial adhesion determines structural integrity and efficient load transfer from fibre to matrix. The mechanical properties of composites can be improved by enhancing the load transfer at the reinforcement/matrix interface by tailoring the interfacial shear strength. A variety of chemical and physical surface treatments – such as fibre whiskerization and surface roughening – can be performed to this end. Unfortunately, these treatments inevitably induce defects or additional phases that could be detrimental to the final composite performance. To overcome this drawback, some research efforts have been devoted to the combination of microscaled (i.e. carbon fibres commonly used in traditional fibrous polymer-matrix composites) and nanoscaled (i.e. carbon nanotubes) materials. As a matter of fact, carbon nanotubes (CNTs) have been attracting great interest since their discovery, due to their outstanding mechanical, thermal and electrical properties, which can exceed those of many other known materials. CNTs have proved to be an extremely strong reinforcement for polymeric-matrix nanocomposites, but they unfortunately tend to aggregate and float, which complicates things. Coating carbon-fibre bundles and fabrics with CNTs in an attempt to distribute nanotubes uniformly across the composite also resulted in a combination of microand nano-reinforcements. Because CNTs fill in any micropores at the interface between polymer and carbon fibre, the final mechanical properties of traditional fibrous composites are expected to be enhanced.

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ENEA-ITALIAN NATIONAL AGENCY FOR NEW TECHNOLOGIES, ENERGY AND SUSTAINABLE ECONOMIC DEVELOPMENT (1) R. GIORGI, SURFACES TECHNOLOGIES LABORATORY-HEAD, (2) E.SALERNITANO, (3) TH.DIKONIMOS, (4) N.LISI, SURFACES TECHNOLOGIES LABORATORY (5) M.F. DE RICCARDIS, UNIT FOR MATERIAL TECHNOLOGIES (6) V. MARTINA, (7) D. CARBONE, COMPOSITES AND NANOSTRUCTURED MATERIALS LABORATORY

The new multiscale hybrid reinforcement is made of carbon nanostructures (carbon nanotubes, carbon nanofibres, etc.) grown directly on commercial carbon-fibre yarns and fabrics with a uniform three-dimensional distribution. The direct growth on the fibres eliminates the problems associated with the orientation of carbon nanostructures within the polymer matrix. Among the techniques used to grow carbon nanomaterials (arc discharge, laser ablation, etc.), only chemical vapour deposition (CVD) methods – based on the olymer-matrix composites reinforced with carbon fibre dissociation of hydrocarbon molecules catalyzed by transition are one of the most commonly used advanced materials metals at high temperature and the dissolution of carbon in a number of sectors, such as aerospace, automotive atoms in the metal catalyst nanoparticles – are capable of industry, energy production, sports, etc. The possibility to growing CNTs directly onto carbon fibres.

No62 January - February 2011 / jec composites magazine
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Research & development

JEC COMPOSITES MAGAZINE - Issue #62 - January/February 2011

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #62 - January/February 2011