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Article
Publication date: 3 December 2018

Elisa Calabrese, Pasquale Longo, Carlo Naddeo, Annaluisa Mariconda, Luigi Vertuccio, Marialuigia Raimondo and Liberata Guadagno

The purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.

Abstract

Purpose

The purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.

Design/methodology/approach

Here, a very detailed evaluation on the stereochemistry of two new ruthenium catalysts evidences the crucial role of the spatial orientation of phenyl groups in the N-heterocyclic carbene ligands in determining the temperature range within the curing cycles is feasible without deactivating the self-healing mechanisms (ring-opening metathesis polymerization reactions) inside the thermosetting resin. The exceptional activity and thermal stability of the HG2MesPhSyn catalyst, with the syn orientation of phenyl groups, highlight the relevant potentiality and the future perspectives of this complex for the activation of the self-healing function in aeronautical resins.

Findings

The HG2MesPhSyn complex, with the syn orientation of the phenyl groups, is able to activate metathesis reactions within the highly reactive environment of the epoxy thermosetting resins, cured up to 180°C, while the other stereoisomer, with the anti-orientation of the phenyl groups, does not preserve its catalytic activity in these conditions.

Originality/value

In this paper, a comparison between the self-healing functionality of two catalytic systems has been performed, using metathesis tests and FTIR spectroscopy. In the field of the design of catalytic systems for self-healing structural materials, a very relevant result has been found: a slight difference in the molecular stereochemistry plays a key role in the development of self-healing materials for aeronautical and aerospace applications.

Details

International Journal of Structural Integrity, vol. 9 no. 6
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 3 December 2018

Massimo Viscardi, Maurizio Arena, Liberata Guadagno, Luigi Vertuccio and Giuseppina Barra

The purpose of this paper is to evaluate the applicative potentiality of functional/self-responsive materials in aeronautics. In particular, the study aims to…

Abstract

Purpose

The purpose of this paper is to evaluate the applicative potentiality of functional/self-responsive materials in aeronautics. In particular, the study aims to experimentally validate the enhancement of structural performances of carbon fibers samples in the presence of nanofillers, as multi-walled carbon nanontubes or microcapsules for the self-healing functionality.

Design/methodology/approach

The paper opted for a mechanical study. Experimental static and dynamic tests on “blank” and modified formulations were performed in order to estimate both strength and damping parameters. A cantilever beam test set-up has been proposed. As a parallel activity, a numerical FE approach has been introduced to assess the correct modeling of the system.

Findings

The paper provides practical and empirical insights about how self-responsive materials react to mechanical solicitations. It suggests that reinforcing a sample positively affects the samples properties since they, de facto, improve the global structural performance. This work highlights that the addition of carbon nanotubes strongly improves the mechanical properties with a simultaneous slight enhancement in the damping performance. Damping properties are, instead, strongly enhanced by the addition of self-healing components. A balanced combination of both fillers could be adopted to increase electrical conductivity and to improve global performance in damping and auto-repairing properties.

Practical implications

The paper includes implications for the use of lightweight composite materials in aeronautics.

Originality/value

This paper fulfills an identified need to study new lightweight self-responsive smart materials for aeronautical structural application.

Details

International Journal of Structural Integrity, vol. 9 no. 6
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 3 October 2016

Martin Kadlec, Robin Hron and Liberata Guadagno

The purpose of this paper is to present the mechanical and morphological characterization of new multifunctional carbon fibre-reinforced composites (CFRCs) that are able…

Abstract

Purpose

The purpose of this paper is to present the mechanical and morphological characterization of new multifunctional carbon fibre-reinforced composites (CFRCs) that are able to overcome two of the main drawbacks of aeronautical composite materials: reduced electrical conductivity and poor flame resistance. Multiwall carbon nanotubes and glycidyl POSS (GPOSS) were used to simultaneously enhance electrical conductivity and flame resistance. The effect of these two combined components on the mechanical and morphological properties of the manufactured CFRCs was analysed.

Design/methodology/approach

This paper describes the mechanical test results obtained for interlaminar shear strength, three-point bending, and tensile and fracture toughness in mode I tests. Carbon fibre-reinforced epoxy resin plates were manufactured in two series with blank resin and CNT+flame retardant GPOSS-enhanced resin.

Findings

The mechanical properties were decreased by no more than 10 per cent by combined influence of CNTs and GPOSS. Agglomerates of CNTs were observed using scanning electron microscopy. The agglomerates were large enough to be visible to the naked eye as black spots on the delaminated fracture surface. The decrease of the mechanical properties could be caused by these agglomerates or by a changed fibre volume content that was affected by the difficult infusion procedure due to high resin viscosity.

Originality/value

If we consider the benefit of CNTs as a nanofiller to increase electrical conductivity and the GPOSS as a component to increase the flame resistance of the resin, the decrease of strength seems to be insignificant.

Details

International Journal of Structural Integrity, vol. 7 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 3 October 2016

Marialuigia Raimondo, Felice De Nicola, Ruggero Volponi, Wolfgang Binder, Philipp Michael, Salvatore Russo and Liberata Guadagno

The purpose of this paper is to describe the first experiments to manufacture self-healing carbon fiber reinforced panels (CFRPs) for the realization of structural…

Abstract

Purpose

The purpose of this paper is to describe the first experiments to manufacture self-healing carbon fiber reinforced panels (CFRPs) for the realization of structural aeronautic components in order to address their vulnerability to impact damage in the real service conditions.

Design/methodology/approach

The developed self-healing system is based on ring-opening metathesis polymerizations reaction of microencapsulated 5-ethylidene-2-norbornene/dicyclopentadiene cyclic olefins using Hoveyda-Grubbs’ first generation catalyst as initiator. In this work, the self-healing resin is infused into a carbon fiber dry preform using an unconventional bulk film infusion technique that has allowed to minimize the filtration effects via a better compaction and reduced resin flow paths. Infrared spectroscopy provides a useful way to identify metathesis products and therefore catalyst activity in the self-healing panel after damage. The damage resistance of the manufactured CFRPs is evaluated through hail and drop tests.

Findings

The self-healing manufactured panels show, after damage, catalyst activity with metathesis product formation, as evidenced by an infrared peak at 966 cm−1. The damage response of CFRPs, detected in accord to the requirements of hail impact for the design of a fuselage in composite material, is very good. The results are very encouraging and can constitute a solid basis for bringing this new technology to the self-healable fiber reinforced resins for aerospace applications.

Originality/value

In this paper, autonomically healing CFRPs with damage resistance and self-healing function are proposed. In the development of self-healing aeronautic materials it is critical that self-healing activity functions in adverse weather conditions and at low working temperatures which can reach values as low as −50°C.

Details

International Journal of Structural Integrity, vol. 7 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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