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Article
Publication date: 7 October 2021

Dibyendu Adak, Donkupar Francis Marbaniang and Subhrajit Dutta

Self-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete…

Abstract

Purpose

Self-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete structure would contribute to a longer service life of the concrete and would make the material more durable and more sustainable. The cementitious mortar with/without incorporating encapsulates at different percentages of slag replacement with the cement mix improves autogenous healing at different ages. Therefore, this study’s aim is to develop a self-healing cementitious matrix for repair and retrofitting of concrete structures.

Design/methodology/approach

In the present work, waste straw pipes are used as a capsule, filled with the solution of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and colloidal nano-silica as self-healing activators. An artificial micro-crack on the control and blended mortar specimens at different percentages of slag replacement with cement (with/without encapsulation) is developed by applying a compressive load of 50% of its ultimate load-carrying capacity. The mechanical strength and ultrasonic pulse velocity, water absorption and chloride ion penetration test are conducted on the concrete specimen before and after the healing period. Finally, the self-healing activity of mortar mixes with/without encapsulation is analysed at different ages.

Findings

The encapsulated mortar mix with 10% of slag content has better self-healing potential than all other mixes considering mechanical strength and durability. The enhancement of the self-healing potential of such mortar mix is mainly due to hydration of anhydrous slag on the crack surface and transformation of amorphous slag to the crystalline phase in presence of encapsulated fluid.

Research limitations/implications

The self-healing activities of the slag-based cementitious composite are studied for a healing period of 90 days only. The strength and durability performance of the cracked specimen may be increased after a long healing period.

Practical implications

The outcome of the work will help repair the cracks in the concrete structure and enhances the service life.

Originality/value

This study identifies the addition encapsulates with a self-healing activator fluid that can recover its strength after minor damage.

Details

International Journal of Structural Integrity, vol. 12 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 3 December 2018

Panagiota Polydoropoulou, Christos Vasilios Katsiropoulos, Andreas Loukopoulos and Spiros Pantelakis

Over the last decades, self-healing materials based on polymers are attracting increasing interest due to their potential for detecting and “autonomically” healing damage…

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Abstract

Purpose

Over the last decades, self-healing materials based on polymers are attracting increasing interest due to their potential for detecting and “autonomically” healing damage. The use of embedded self-healing microcapsules represents one of the most popular self-healing concepts. Yet, extensive investigations are still needed to convince on the efficiency of the above concept. The paper aims to discuss these issues.

Design/methodology/approach

In the present work, the effect of embedded self-healing microcapsules on the ILSS behavior of carbon fiber reinforced composite materials has been studied. Moreover, the self-healing efficiency has been assessed. The results of the mechanical tests were discussed supported by scanning electron microscope (SEM) as well as by Attenuated Total Reflection–Fourier-transform infrared spectroscopy (ATR–FTIR) analyses.

Findings

The results indicate a general trend of a degraded mechanical behavior of the enhanced materials, as the microcapsules exhibit a non-uniform dispersion and form agglomerations which act as internal defects. A remarkable value of the self-healing efficiency has been found for materials with limited damage, e.g. matrix micro-cracks. However, for significant damage, in terms of large matrix cracks and delaminations as well as fiber breakages, the self-healing efficiency is limited.

Originality/value

The results obtained by SEM analysis as well as by ATR–FTIR spectroscopy constitute a strong indication that the self-healing mechanism has been activated. However, further investigation should be conducted in order to provide definite evidence.

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

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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Article
Publication date: 21 May 2020

Nitin Kumar Gupta, Gananath Doulat Thakre and Manoj Kumar

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for…

Abstract

Purpose

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for enhanced tribo-performance of the developed material.

Design/methodology/approach

A unique procedure has been adopted to convert the sand casted Al6061 into self-healing material by piercing a low melting point solder material with and without MoS2. Taguchi-based L9 orthogonal array has been used to optimize the number of experiments and analyze the influence of operating parameters such as speed, sliding distance and load on material wear.

Findings

The results reveal that the paper shows the self-healing and self-repair is possible in metal through piercing low melting point alloy. Then, the load has a significant influence over other input parameters in predicting the wear behavior of developed material. Moreover, addition of MoS2 does not affect the tribo-performance of the developed material. The study concludes that the developed self-healing Al6061 has huge potential to be used in mechanical industry.

Research limitations/implications

The concept of self-healing in metals are very challenging task due to very slow diffusion rate of atoms at room temperature. Therefore, researchers are encouraged to explore the other new techniques to create self-healing in metals.

Practical implications

The self-healing materials had shown huge potential to be used in mechanical industry. The current investigation established a structural fabrication and testing procedure to understand the effects of various parameters on wear. The conclusion from the experimentation and optimization helps researchers to developed and create self-healing in metals.

Originality/value

The previous research works were not focused on the study of tribological property of self-healing metal composite. With the best of author’s knowledge, no one has reported tribological study, as well as optimization of parameters such as speed, load and sliding distance on wear in self-healing metals composite.

Details

Journal of Engineering, Design and Technology , vol. 18 no. 5
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 6 March 2017

Mehdi Shahidi Zandi and Majdeh Hasanzadeh

The aim of this work is to investigate the self-healing performance of epoxy coatings containing microcapsules. The microcapsule-based coatings were applied on AA6061 Al…

Abstract

Purpose

The aim of this work is to investigate the self-healing performance of epoxy coatings containing microcapsules. The microcapsule-based coatings were applied on AA6061 Al alloy and immersed in 3.5 per cent NaCl solution.

Design/methodology/approach

Microcapsules with urea–formaldehyde as the shell and linseed oil as the healing agent were prepared by in situ polymerization in an oil-in-water emulsion. For the sake of an optimum self-healing system, some coating samples were prepared by using different microcapsule concentrations: 0, 5, 10 and 20 Wt.%. The scratch-filling efficiency as the theoretical estimate of the self-healing performance was calculated for the coating samples with different microcapsule concentrations. The scratch-sealing efficiency (SSE) as a particularly crucial parameter in the self-healing evaluation of coatings was measured by both electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques.

Findings

According to EIS and EN results, the coating samples containing 5 and 10 per cent microcapsules provided the insignificant self-healing performance, while the coating sample containing 20 per cent microcapsules exhibited the acceptable self-healing performance to AA6061 alloy in the NaCl solution. The measured SSE values confirmed the good agreement of EN data with electrochemical parameters obtained from the EIS technique.

Originality/value

This work is an attempt to evaluate the self-healing performance of microcapsule-based epoxy coatings applied on AA6061 Al alloy in sea water.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 2 January 2018

Hongsheng Luo, Xingdong Zhou, Yuncheng Xu, Huaquan Wang, Yongtao Yao, Guobin Yi and Zhifeng Hao

This paper aims to exploit shape-memory polymers as self-healable materials. The underlying mechanism involved the thermal transitions as well as the enrichment of the…

Abstract

Purpose

This paper aims to exploit shape-memory polymers as self-healable materials. The underlying mechanism involved the thermal transitions as well as the enrichment of the healing reagents and the closure of the crack surfaces due to shape recovery. The multi-stimuli-triggered shape memory composite was capable of self-healing under not only direct thermal but also electrical stimulations.

Design/methodology/approach

The shape memory epoxy polymer composites comprising the AgNWs and poly (ε-caprolactone) were fabricated by dry transfer process. The morphologies of the composites were investigated by the optical microscope and scanning electron microscopy (SEM). The electrical conduction and the Joule heating effect were measured. Furthermore, the healing efficiency under the different stimuli was calculated, whose dependence on the compositions was also discussed.

Findings

The AgNWs network maintained most of the pathways for the electrons transportation after the dry transfer process, leading to a superior conduction and flexibility. Consequently, the composites could trigger the healing within several minutes, as applied with relatively low voltages. It was found that the composites having more the AgNWs content had better electrically triggered performance, while 50 per cent poly (ε-caprolactone) content endowed the materials with max healing efficiency under thermal or electrical stimuli.

Research limitations/implications

The findings may greatly benefit the application of the intelligent polymers in the fields of the multifunctional flexible electronics.

Originality/value

Most studies have by far emphasized on the direct thermal triggered cases. Herein, a novel, flexible and conductive shape memory-based composite, which was capable of self-healing under the thermal or electrical stimulations, has been proposed.

Details

Pigment & Resin Technology, vol. 47 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 7 March 2016

Pooneh Kardar

– The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings.

Abstract

Purpose

The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings.

Design/methodology/approach

In this research, microcapsule with isophorone diisocyanate (IDPI) core and polyurethane shell were prepared and used in self-healing coatings. Microcapsules synthesised were characterised by thermal gravimeter and infrared spectra. The microcapsules were dispersed in an acrylic-melamine clearcoat, and the scratch resistance was evaluated.

Findings

The triplex product and the formed polyurethane bonds were confirmed by thermal gravimeter and infrared spectra. In addition, smooth spherical particles with a diameter of 1.5 to 1.7 micronmeters were observed by a scanning electron microscope. The microcapsules dispersed in an acrylic-melamine clearcoat increased the scratch resistance of coatings. Also, the self-healing feature of those coatings was proved.

Research limitations/implications

The size of microcapsules can affect its dispersion in the clearcoat and consequently affect the properties of the cured films.

Practical implications

The self-healing coatings are interested for many industries such as building and automotive industries. The reported data can be used by the formulators working in the R & D departments.

Social implications

Self-healing systems are considered as one of the smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications.

Originality/value

The application of microcapsules in the coating as healing agents is a great challenge, which has been hardly investigated so far. In the current research, the effect of polyurethane-IDPI microcapsules in an automotive clearcoat as a self-healing coating was investigated.

Details

Pigment & Resin Technology, vol. 45 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

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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: 6 April 2021

Raj Kumar Pittala, Satish Ben B., Syam Kumar Chokka and Niranjan Prasad

Microcapsule-embedded autonomic healing materials have the ability to repair microcracks when they come into contact with the crack by releasing the healing agent. The…

Abstract

Purpose

Microcapsule-embedded autonomic healing materials have the ability to repair microcracks when they come into contact with the crack by releasing the healing agent. The microcapsules with specific shape and thickness effect in releasing healing agent to the cracked surfaces. Thus, the purpose of this paper is to know the load bearing capacity of the self-healing microcapsules and the stresses developed in the material.

Design/methodology/approach

In the present study, self-healing microcapsule is modelled and integrated with the polymer matrix composite. The aim of the present study is to investigate failure criteria of Poly (methyl methacrylate) microcapsules by varying the shell thickness, capsule diameter and loading conditions. The strength of the capsule is evaluated by keeping the shell thickness as constant and varying the capsule diameter. Uniformly distributed pressure loads were applied on the capsule-reinforced polymer matrix composite to assess the failure strength of capsules and composite.

Findings

It is observed from the results that the load required to break the capsules is increasing with the increase in capsule diameter. The failure strength of microcapsule with 100 µm diameter and 5 µm thickness is observed as 255 MPa. For an applied load range of 40–160 N/mm2 on the capsules embedded composite, the maximum stress developed in the capsules is observed as 308 MPa.

Originality/value

Failure strengths of microcapsules and stresses developed in the microcapsule-reinforced polymer composites were evaluated.

Details

World Journal of Engineering, vol. 18 no. 3
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 March 2013

G.C. Kordas, A.C. Balaskas, I.A. Kartsonakis and E.K. Efthimiadou

The purpose of this paper is to study the release of corrosion inhibitor from nanocontainers and to show that it can be released due to reaction with the substrate induced…

Abstract

Purpose

The purpose of this paper is to study the release of corrosion inhibitor from nanocontainers and to show that it can be released due to reaction with the substrate induced by corrosion. This is called self‐healing of corrosion. Raman spectroscopy was used to show that reaction after scratching of the surface and corrosion of the substrate.

Design/methodology/approach

TiO2 nanocontainers loaded with 8‐hydroxyquinoline (8‐HQ) were placed onto a copper substrate and wetted with in 0.05 M NaCl solution. The Raman spectrum of the modified copper surface was attributed to the Cu(8‐Q)2 compound. The incorporation of loaded nanocontainers into epoxy coatings showed enhanced protection against corrosion. Artificial defects were formed on the coatings in order to evaluate the corrosion process and the possible self‐healing effect. The Raman spectra in the scratch tentatively assigned to Cu(8‐Q)2 compound. This result shows that the enhanced anti‐corrosive properties of the films with loaded nanocontainers can be attributed to the released inhibitor from the nanocontainer.

Findings

The authors found that the corrosion of copper substrate induces the release of hydroxyquinoline and formation of a chelate. This is the self‐healing phenomenon.

Practical implications

This can be employed for self‐healing in all structures, such as mechanical properties of bridges, etc.

Social implications

Damage occurs in all structures: the cost is immense – millions of dollars. Damage also occurs after an earthquake, accidents, etc. Self‐repairing is the key issue in modern science, therefore this article is of great importance.

Originality/value

The originality is that the authors showed, with Raman spectroscopy, that the chemicals in the nanocontainers in the coatings are released by the corrosion induced in the metal. This is the first spectroscopic proof of self‐healing.

Details

International Journal of Structural Integrity, vol. 4 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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