Evaluation of the Mechanical Properties of Microcapsule-Based Self-Healing Composites

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 slight reduction of the healing efficiency. These results can constitute the basis to design systems with high regenerative ability and appropriate mechanical performance.

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Mechanical Properties Assessment of Low-Content Capsule-Based Self-Healing Structural Composites

Applied Sciences ◽

10.3390/app10175739 ◽

2020 ◽

Vol 10 (17) ◽

pp. 5739

Author(s):

Xenia Tsilimigkra ◽

Dimitrios Bekas ◽

Maria Kosarli ◽

Stavros Tsantzalis ◽

Alkiviadis Paipetis ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Flexural Strength ◽

Mechanical Performance ◽

Urea Formaldehyde ◽

Healing Process ◽

Experimental Results ◽

Self Healing ◽

Healing Efficiency ◽

A Minor

Microcapsule-based carbon fiber reinforced composites were manufactured by wet layup, in order to assess their mechanical properties and determine their healing efficiency. Microcapsules at 10%wt. containing bisphenol-A epoxy, encapsulated in a urea formaldehyde (UF) shell, were employed with Scandium (III) Triflate (Sc (OTf)3) as the catalyst. The investigation was deployed with two main directions. The first monitored changes to the mechanical performance due to the presence of the healing agent within the composite. More precisely, a minor decrease in interlaminar fracture toughness (GIIC) (−14%), flexural strength (−12%) and modulus (−4%) compared to the reference material was reported. The second direction evaluated the healing efficiency. The experimental results showed significant recovery in fracture toughness up to 84% after the healing process, while flexural strength and modulus healing rates reached up to 14% and 23%, respectively. The Acoustic Emission technique was used to support the experimental results by the onsite monitoring.

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Recyclable Self-Healing Polyurethane Cross-Linked by Alkyl Diselenide with Enhanced Mechanical Properties

Polymers ◽

10.3390/polym11050773 ◽

2019 ◽

Vol 11 (5) ◽

pp. 773 ◽

Cited By ~ 3

Author(s):

Yuqing Qian ◽

Xiaowei An ◽

Xiaofei Huang ◽

Xiangqiang Pan ◽

Jian Zhu ◽

...

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Amide Bond ◽

Self Healing ◽

Healing Efficiency ◽

Polyurethane Networks ◽

Combined Action ◽

Cross Linker ◽

Dynamic Structures ◽

External Interventions

Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.

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Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

Advances in Materials Science and Engineering ◽

10.1155/2016/8271214 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Haoliang Huang ◽

Guang Ye

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Elastic Modulus ◽

Cementitious Materials ◽

Self Healing ◽

Negative Effects ◽

Numerical Studies ◽

Healing Efficiency ◽

The Impact ◽

Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

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Dynamic Mussel-Inspired Chitin Nanocomposite Hydrogels for Wearable Strain Sensors

Polymers ◽

10.3390/polym12061416 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1416 ◽

Cited By ~ 3

Author(s):

Pejman Heidarian ◽

Abbas Z. Kouzani ◽

Akif Kaynak ◽

Ali Zolfagharian ◽

Hossein Yousefi

Keyword(s):

Mechanical Properties ◽

Polyacrylic Acid ◽

Strain Sensors ◽

Self Healing ◽

Network Stability ◽

Ferric Ions ◽

Trade Off ◽

Nanocomposite Hydrogels ◽

Healing Efficiency ◽

Hydrogel Network

It is an ongoing challenge to fabricate an electroconductive and tough hydrogel with autonomous self-healing and self-recovery (SELF) for wearable strain sensors. Current electroconductive hydrogels often show a trade-off between static crosslinks for mechanical strength and dynamic crosslinks for SELF properties. In this work, a facile procedure was developed to synthesize a dynamic electroconductive hydrogel with excellent SELF and mechanical properties from starch/polyacrylic acid (St/PAA) by simply loading ferric ions (Fe3+) and tannic acid-coated chitin nanofibers (TA-ChNFs) into the hydrogel network. Based on our findings, the highest toughness was observed for the 1 wt.% TA-ChNF-reinforced hydrogel (1.43 MJ/m3), which is 10.5-fold higher than the unreinforced counterpart. Moreover, the 1 wt.% TA-ChNF-reinforced hydrogel showed the highest resistance against crack propagation and a 96.5% healing efficiency after 40 min. Therefore, it was chosen as the optimized hydrogel to pursue the remaining experiments. Due to its unique SELF performance, network stability, superior mechanical, and self-adhesiveness properties, this hydrogel demonstrates potential for applications in self-wearable strain sensors.

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Adaptable Eu-containing polymeric films with dynamic control of mechanical properties in response to moisture

Soft Matter ◽

10.1039/c9sm02440a ◽

2020 ◽

Vol 16 (9) ◽

pp. 2276-2284 ◽

Cited By ~ 7

Author(s):

Zichao Wei ◽

Srinivas Thanneeru ◽

Elena Margaret Rodriguez ◽

Gengsheng Weng ◽

Jie He

Keyword(s):

Mechanical Properties ◽

Optical Properties ◽

Polymer Films ◽

Dynamic Control ◽

Polymeric Films ◽

Self Healing ◽

Healing Efficiency

Moisture that competes with dipicolylamine to bind Eu dynamically controls the mechanical and optical properties of polymer films, as well as their self-healing efficiency.

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Effect of Kenaf Alkalization Treatment on Morphological and Mechanical Properties of Epoxy/Silica/Kenaf Composite

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.35.22743 ◽

2018 ◽

Vol 7 (4.35) ◽

pp. 258 ◽

Cited By ~ 9

Author(s):

Che Nor Aiza Jaafar ◽

Muhammad Asyraf Muhammad Rizal ◽

Ismail Zainol

Keyword(s):

Mechanical Properties ◽

Sodium Hydroxide ◽

Mechanical Performance ◽

Flexural Modulus ◽

Charpy Impact ◽

Charpy Impact Test ◽

Curing Temperature ◽

Curing Process ◽

Scanning Calorimetry ◽

Kenaf Fiber

The mechanical performance of silica modified epoxy at various concentration of sodium hydroxide for surface treatment of multi-axial kenaf has been analyzed. Epoxy resin with amine hardener was modified with silica powder at 20 phr and toughened by treated kenaf fiber that immerses in various concentrations of sodium hydroxide (NaOH) ranging from 0% to 9% of weight. The composite was analyzed through differential scanning calorimetry (DSC) to ensure complete curing process. The mechanical properties of the composites were analyzed through flexural test, Charpy impact test and DSC to ensure the complete curing process. DSC analysis results show epoxy sample was completely cured at above 73°C that verifies the curing temperature for preparation for the composite. Hence, 3% NaOH treated composite exhibits the best mechanical properties, with 10.6 kJ/m2 of impact strength, 54.1 MPa of flexural strength and 3.5 GPa of flexural modulus. It is due to the improvement of fiber-matrix compatibility. Analysis by SEM also revealed that a cleaner surface of kenaf fiber treated at 3% NaOH shown cleaner surface, thus, in turn, improve surface interaction between fiber and matrix of the composite. The composites produced in this work has high potential to be used in automotive and domestics appliances.

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A Preliminary Study on Cryogenic Mechanical Properties of Epoxy Blend Matrices and SiO2/Epoxy Nanocomposites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.312.211 ◽

2006 ◽

Vol 312 ◽

pp. 211-216 ◽

Cited By ~ 15

Author(s):

Shao Yun Fu ◽

Qin-Yan Pan ◽

Chuan Jun Huang ◽

Guo Yang ◽

Xin-Hou Liu ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Room Temperature ◽

Sol Gel ◽

Sio2 Nanoparticles ◽

Diglycidyl Ether ◽

Slight Reduction ◽

Epoxy Nanocomposites ◽

Sol Gel Process ◽

Cryogenic Mechanical Properties

Epoxy blend matrices were prepared by incorporating polyurethane-epoxy into diglycidyl ether of bisphenol-F (DGEBF) type epoxy while SiO2/epoxy nanocomposites were made using DGEBF type epoxy and tetraethylorthosilicate (TEOS) via a sol-gel process. The mechanical properties including tensile and impact properties at 77 K of the matrices and nanocomposites were studied. The mechanical properties at room temperature were also given for the purpose of comparison with the cryogenic mechanical properties. The results showed that the incorporation of polyurethane-epoxy with a proper content into DGEBF type epoxy enhanced the mechanical properties at both room and cryogenic temperatures. Addition of SiO2 nanoparticles to DGEBF type epoxy led to significant increase in tensile strength at cryogenic temperature (77 K) while no evident change in tensile strength at room temperature. In addition, a slight enhancement by the addition of 2 wt % silica while a slight reduction by the addition of 4 wt % silica were observed in impact energy.

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Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete

MRS Proceedings ◽

10.1557/opl.2016.7 ◽

2016 ◽

Vol 1813 ◽

Author(s):

L. E. Rendon Diaz Miron ◽

M. E. Lara Magaña

Keyword(s):

Mechanical Properties ◽

Crack Formation ◽

Healing Process ◽

Self Healing ◽

Reaction Products ◽

Calcium Carbonate Precipitation ◽

Broad Perspective ◽

Healing Efficiency ◽

Tensile Forces ◽

Solubility Ratio

ABSTRACTTensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.

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Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

Materials ◽

10.3390/ma13184164 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4164 ◽

Cited By ~ 1

Author(s):

Hayeon Kim ◽

Hyeongmin Son ◽

Joonho Seo ◽

H. K. Lee

Keyword(s):

Mechanical Properties ◽

Mercury Intrusion Porosimetry ◽

Tap Water ◽

Bottom Ash ◽

Self Healing ◽

Mixing Process ◽

Mercury Intrusion ◽

Healing Efficiency ◽

Cement Based Materials ◽

Healing Agent

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

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