Effect Of TETA Microcapsules On Self-healing Ability Of Dual Component Epoxy System (original) (raw)
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Evaluation of the Mechanical Properties of Microcapsule-Based Self-Healing Composites
International Journal of Aerospace Engineering, 2016
Self-healing materials are beginning to be considered for applications in the field of structural materials. For this reason, in addition to self-healing efficiency, also mechanical properties such as tensile and compressive properties are beginning to become more and more important for this kind of materials. In this paper, three different systems based on epoxy-resins/ethylidene-norbornene (ENB)/Hoveyda-Grubbs 1st-generation (HG1) catalyst are investigated in terms of mechanical properties and healing efficiency. The experimental results show that the mechanical properties of the self-healing systems are mainly determined by the chemical nature of the epoxy matrix. In particular, the replacement of a conventional flexibilizer (Heloxy 71) with a reactive diluent (1,4-butanediol diglycidyl ether) allows obtaining self-healing materials with better mechanical properties and higher thermal stability. An increase in the curing temperature causes an increase in the elastic modulus and a...
Self-healing epoxy composites: preparation, characterization and healing performance
Low velocity impact damage is common in fiber reinforced composites, which leads to micro-crack and interfacial debonding, where damage is microscopic and invisible. The concept of self-healing composites can be a way of overcoming this limitation and extending the life expectancy while expanding their usage in structural applications. In the current study, extrinsic self-healing concept was adopted using urea-formaldehyde microcapsules containing room temperature curing epoxy resin system (SC-15) as the healing agent prepared by in situ polymerization. Microcapsules were characterized using Fourier transform infrared spectroscopy (FTIR) for structural analysis. Size and shape of microcapsules were studied using optical microscopy and scanning electron microscopy (SEM). Size of the microcapsules was between 30 and 100 m. Thermal characterization was carried out using thermogravimetric analysis. Microcapsules were thermally stable till 210◦C without any significant decomposition. Fiber reinforced composite fabrication was carried out in three different steps. In the first step, epoxy resin was encapsulated in urea-formaldehyde shell material, which was confirmed by FTIR analysis. In the next step, encapsulation of amine hardener was achieved by vacuum infiltration method. These two different microcapsules were added with epoxy at 10:3 ratio and composite fabrication was done with hand layup method. Finally, healing performance was measured in terms of low velocity impact test and thermoscopy analysis. Low velocity impact test with 30 J and 45 J impact loads confirmed the delamination and micro-crack in composite materials and subsequent healing recovery observed in terms of damaged area reduction and restoration of mechanical properties.
Robust synthesis of epoxy resin-filled microcapsules for application to self-healing materials
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, 2016
Mechanically and thermally robust microcapsules containing diglycidyl ether bisphenol A-based epoxy resin and a high-boiling-point organic solvent were synthesized in high yield using in situ polymerization of urea and formaldehyde in an oil-in-water emulsion. Microcapsules were characterized in terms of their size and size distribution, shell surface morphology and thermal resistance to the curing cycles of commercially used epoxy polymers. The size distribution of the capsules and characteristics such as shell thickness can be controlled by the specific parameters of microencapsulation, including concentrations of reagents, stirrer speed and sonication. Selected microcapsules, and separated core and shell materials, were analysed using thermogravimetric analysis and differential scanning calorimetry. It is demonstrated that capsules lose minimal 2.5 wt% at temperatures no higher than 120°C. These microcapsules can be applied to self-healing carbon fibre composite structural materi...
Advanced Materials Letters, 2017
The objective of this work was to study the effect of incorporating a microencapsulated healing agent in an epoxy matrix and E-glass fiber reinforced composite. Microcapsules were prepared via oil-in-water emulsion polymerization method with dicyclopentadiene as core material and poly(urea-formaldehyde) (PUF) as shell material. The suitable formulation for the epoxy matrix was selected based on the study of the rheological and mechanical properties of various chemical systems. Different amounts of microcapsules were incorporated and the most appropriate processing method (mixing, curing and postcuring cycle) was evaluated. Furthermore, flexural and fracture tests were carried out and the distribution of the capsules as well as the interfacial adhesion with the epoxy matrix were studied. Finally, the processing of fiber reinforced composites, with and without microcapsules, was carried out by compression molding and the mechanical properties of the composites were studied (modulus and maximum flexural strain) from testing three-point bending. The resulting samples with 32 wt. % of fibers and matrices with no microcapsules were compared. Compression molding technique did not affect the integrity of the microcapsules inside the composites.
Al-Azhar Dental Journal for Girls, 2018
Purpose: The present study aimed to investigate the effect of incorporation of the new Triethylene glycoldimethacrylate and N,N-Bis(2-hydroxyethyl)-p-toluidine (TEGDMA)-(DHEPT) in polyurea formaldehyde (PUF) micro-capsules into an experimental dental resin composite on the flexural strength and fracture toughness and the evaluation of its self-healing efficacy. Materials and Methods: Polyurea formaldehyde microcapsules were synthesized by insitu polymerization technique, encapsulating a triethylene glycol dimethacrylate and dihydroxy ethyl para toluidine (TEGDMA-DHEPT) as a healing liquid, then experimental composite resin is prepared. Microcapsules are incorporated in the resin composite with concentrations 0%, 2.5%, 5%, 7.5% and 10%, then experimental resin composite specimens were fabricated. Fracture toughness and flexural strength were examined by three point loading using universal testing machine till fracture. The fracture toughness was evaluated by using single edge V-notched beam method, self healing efficacy is evaluated as the ratio between the healed fracture toughness and the virgin fracture toughness. Results: Regarding flexural strength results, it was found that the 0% group has the highest flexural strength while the 10% group had the lowest flexural strength. On the other hand, on evaluating the results, of 7.5% group it was found that this concentration did not affect the flexural strength remarkably. Regarding the virgin fracture toughness results, 0% group has the highest flexural strength, while the 10% group the lowest flexural strength, specimens were fractured and healed, then fractured again to measure the healed fracture toughness, on examining the results of the healed fracture toughness, it was found that no significant difference between 0% and 2.5% as no healing occur at such specimen, Also the results showed that the highest healed fracture toughness was in 5%, followed by 7.5%, followed by 10%. The self-healing efficacy increased to Codex : 66/1810
Preparation and Property Investigation of Epoxy/Amine Micro/Nanocapsule Based Self-healing Coatings
International Polymer Processing, No. 5, 2018
Autonomous self-healing was achieved by synthesizing epoxy coatings which contain dual micro/nanocapsules; epoxy and amine. Epoxy micro/nanocapsules were prepared by an in situ polymerization process and amine microcapsules were fabricated by vacuum infiltration of diethylenetriamine into nanoporous hollow glass microspheres. Both types of capsules were embedded into epoxy matrix. When cracks were created and started to grow in the coating, the micro/nano-capsules near the crack were ruptured and released their contents. As a result of curing reaction between released curing agents (epoxy and amine), healing of the cracked sites was completed. In this work, some properties of epoxy/amine micro/nanocapsule based self-healing coatings such as morphology of micro/nanocapsule and coating, healing and corrosion properties were studied. Also thermal stability and adhesion properties of this kind of coating were evaluated comprehensively. It was found out that optimum mass ratio of epoxy/amine capsules ratio is 1 : 1 and the highest healing efficiency was achieved for a total micro/nanocapsule concentration of 15 wt.%. Regarding thermal and adhesion behavior of coatings, it was observed that adding micro/nano-capsules to epoxy matrix did not change these properties significantly which means self-healing characteristics were achievable without deteriorating other properties.
Healing efficiency of epoxy-based materials for structural application
AIP Conference Proceedings, 2012
Several systems to develop self-repairing epoxy resins have recently been formulated. In this paper the effect of matrix nature and curing cycle on the healing efficiency and dynamic mechanical properties of self-healing epoxy resins were investigated. We discuss several aspects by transferring self-healing systems from the laboratory scale to real applications in the aeronautic field, such as the possibility to choose systems with increased glass transition temperature, high storage modulus and high values in the healing functionality under real working conditions.
Applications of Microcapsules in Self-Healing Polymeric Materials
Microencapsulation - Processes, Technologies and Industrial Applications [Working Title]
Self-healing polymeric materials have a great potential to be explored and utilized in many applications such as engineering and surface coating. Various smart materials with self-healing ability and unique self-healing mechanisms have been reported in recent publications. Currently, the most widely employed technique is by embedding microcapsules that contain a healing agent into the bulk polymer matrix. When cracks develop in the polymer matrix, the curing agent is released from the microcapsules to cross-link and repair the cracks. Microencapsulation of the healing agent in the core can be achieved by in situ polymerizing of shell material. This chapter presents a general review on self-healing materials, and particularly, self-healing of epoxy matrices that includes epoxy composite and epoxy coating by microencapsulation technique. Microencapsulation processes, including types of resin used, processing parameters such as core/shell ratio, concentration of emulsifiers, viscosities of aqueous and organic phases and stirring rate are discussed.
Cure behavior and mechanical properties of structural self-healing epoxy resins
Journal of Polymer Science Part B-polymer Physics, 2010
Advances in the growing use of polymer composites in aerospace applications explore the possibility in the development of smart materials capable of self-repair. In this article, we have formulated and characterized a multifunctional autonomically healing composite inspired by the design of White et al. Microcapsules containing dicyclopentadiene (DCPD) and powders of Grubbs first generation catalyst were embedded in an epoxy formulation and both the epoxy precursor and the composite were cured up to the temperature of 120 C that preserves the activity of the catalyst. The results on the cure behavior of an epoxy matrix for self-healing material and the influence of the components related to self-healing func-tion on the dynamic-mechanical properties are investigated. The presence of catalyst powder causes a slight decrease in the elastic modulus value with respect to the epoxy matrix. At variance, a large recovery in this parameter is gained for the self-healing specimen, proving that well-distributed microcapsules contribute to improve the mechanical properties. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000-000, 2010