scholarly journals Effect of a Healing Agent on the Curing Reaction Kinetics and Its Mechanism in a Self-Healing System

2018 ◽  
Vol 8 (11) ◽  
pp. 2241 ◽  
Author(s):  
Xianfeng Wang ◽  
Ming Zhang ◽  
Feng Xing ◽  
Ningxu Han
Keyword(s):  
Reaction Kinetics ◽  
Epoxy Resin ◽  
Reaction Order ◽  
Glycidyl Ether ◽  
Self Healing ◽  
Curing Reaction ◽  
Healing System ◽  
Mass Fractions ◽  
Healing Agent ◽  
Butyl Glycidyl Ether

Self-healing cementitious composites have been developed by using microcapsules. In this study, the effect of the healing agent on the crosslinking and curing reaction kinetics was analyzed. The effect of the diluent n-butyl glycidyl ether (BGE) on the reaction was investigated for five fractions, namely 10.0%, 12.5%, 15.0%, 17.5%, and 20.0% mass fractions to epoxy resin. The Kissinger and Crane equations were used to obtain the activation energy and reaction order with different mass fractions of diluent, as well as the kinetic parameters of the curing reaction. The optimal fraction of BGE was determined as 17.5%. Likewise, the effect of the curing agent MC120D on the reaction kinetics was investigated for 10%, 20%, 30%, 40%, and 50% mass fractions to the diluted epoxy resin. The optimal fraction was determined as 20%. The mechanism of the curing reaction with the healing agent was investigated. The infrared spectra of the cured products of 20% MC120D with BGE/E51 (0.0%, 12.5%, 15.0%, 20.0%, 100%) were analyzed. It is shown that not only the epoxy resin E-51 was cured, but also that the BGE was involved in the cross-linking reaction of the epoxy resin E-51 with MC120D.

scholarly journals Preparation and Characterization of Nano-CaCO3/Ceresine Wax Composite Shell Microcapsules Containing E-44 Epoxy Resin for Self-Healing of Cement-Based Materials

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 197
Author(s):  
Wei Du ◽  
Erwang Li ◽  
Runsheng Lin
Keyword(s):  
Epoxy Resin ◽  
Recovery Rate ◽  
Composite Shell ◽  
Chloride Ion ◽  
Self Healing ◽  
The Core ◽  
Core Content ◽  
Cement Based Materials ◽  
Healing Agent ◽  
Melt Condensation

As an intelligent material, microcapsules can efficiently self-heal internal microcracks and microdefects formed in cement-based materials during service and improve their durability. In this paper, microcapsules of nano-CaCO3/ceresine wax composite shell encapsulated with E-44 epoxy resin were prepared via the melt condensation method. The core content, compactness, particle size distribution, morphologies, chemical structure and micromechanical properties of microcapsules were characterized. The results showed that the encapsulation ability, mechanical properties and compactness of microcapsules were further improved by adding nano-CaCO3 to ceresine wax. The core content, elastic modulus, hardness and weight loss rate (60 days) of nano-CaCO3/ceresine wax composite shell microcapsules (WM2) were 80.6%, 2.02 GPA, 72.54 MPa and 1.6%, respectively. SEM showed that WM2 was regularly spherical with a rough surface and sufficient space inside the microcapsules to store the healing agent. The incorporation of WM2 to mortar can greatly improve the self-healing ability of mortar after pre-damage. After 14 days of self-healing, the compressive strength recovery rate, proportion of harmful pores and chloride ion diffusion coefficient recovery rate increased to 90.1%, 45.54% and 79.8%, respectively. In addition, WM2 also has good self-healing ability for mortar surface cracks, and cracks with initial width of less than 0.35 mm on the mortar surface can completely self-heal within 3 days.

scholarly journals Preparation and Characterization of Microcrystalline Wax/Epoxy Resin Microcapsules for Self-Healing of Cementitious Materials

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1725
Author(s):  
Wei Du ◽  
Quantao Liu ◽  
Runsheng Lin ◽  
Xin Su
Keyword(s):  
Epoxy Resin ◽  
Size Distribution ◽  
Weight Ratio ◽  
Cementitious Materials ◽  
Self Healing ◽  
Surface Cracks ◽  
Preparation Temperature ◽  
Core Content ◽  
Healing Agent

Self-healing of cracks in cementitious materials using healing agents encapsulated in microcapsules is an intelligent and effective method. In this study, microcapsules were prepared by the melt–dispersion–condensation method using microcrystalline wax as the shell and E-51 epoxy resin as the healing agent. The effects of preparation process parameters and microcrystalline wax/E-51 epoxy resin weight ratio on the core content, particle size distribution, thermal properties, morphology, and chemical composition of microcapsules were investigated. The results indicated that the optimal parameters of the microcapsule were microcrystalline wax/E-51 epoxy resin weight ratio of 1:1.2, stirring speed of 900 rpm, and preparation temperature of 105 °C. The effects of microcapsules on pore size distribution, pore structure, mechanical properties, permeability, and ultrasonic amplitude of mortar were determined, and the self-healing ability of mortar with different contents of microcapsules was evaluated. The optimal content of microcapsules in mortars was 4% of the cement weight, and the surface cracks of mortar containing microcapsules with an initial width of 0.28 mm were self-healed within three days, indicating that microcapsules have excellent self-healing ability for cementitious materials.

Fatigue response of a solid state self-healing resin

2020 ◽  
pp. 096739112095509
Author(s):  
Mohd Suzeren Md Jamil ◽  
Noor Nabilah Muhamad ◽  
Wan Naqiuddin Wan Zulrushdi
Keyword(s):  
Fatigue Life ◽  
Solid State ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Healing Process ◽  
Fatigue Tests ◽  
Self Healing ◽  
Healing System ◽  
Healing Agent ◽  
Modified Epoxy

The present work verified the capability of a solid state self-healing system for retarding or arresting fatigue cracks in epoxy materials subjected to cyclic loading at room temperature. A solid state self-healing material is demonstrated using a thermosetting epoxy polymer which was modified by incorporating a linear thermoplastic polydiglycidyl ether bisphenol-A (PDGEBA) as a healing agent. The stress-controlled constant amplitude (CA) tensile fatigue behavior at stress ratio, R = 0.1 and frequency 10 Hz for both the neat and the modified epoxy was investigated. Fatigue life and residual strength degradation were continuously monitored during the fatigue tests. The modified epoxy fatigue life was shown to be increased by ∼50% after healing periods. The fatigue-healing process was proven through the surface and cross-section resin morphology analyses using microscopy optic and scanning electron microscope (SEM). On the whole, the solid state self-healing system has proven to be very effective in obstructing fatigue crack propagation, effectively improved the self-healing polymeric material to achieve higher endurance limits.

Microscopic Tests on Evaluation of Self-Healing Efficiency in Cementitious Materials with a Novel Self-Healing System

2020 ◽  
Vol 996 ◽  
pp. 104-109 ◽  
Author(s):  
Zhen Hong Yang ◽  
Xian Feng Wang ◽  
Ning Xu Han ◽  
Feng Xing
Keyword(s):  
Joint Action ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Self Healing ◽  
Test Results ◽  
Expansive Agent ◽  
Healing System ◽  
Healing Efficiency ◽  
Healing Agent

In this study, Na2CO3 solution as a self-healing agent was impregnated in LWA for autonomic self-healing on cracked cementitious material. The results showed that under the joint action of expansive agent, crystalline additive, phosphate and carbonate, the crack area showed a high self-healing efficiency (close to 70%) after curing in the still water 28d. SEM-EDS test results showed that in addition to ettringite and C-S-H/C-A-S-H, there was also a large amount of CaCO3 crystal in the depths of the crack.

scholarly journals Preparation and Characterization of Microencapsulated Ethylenediamine with Epoxy Resin for Self-healing Composites

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Liye Yuan ◽  
Tongqing Sun ◽  
Honglin Hu ◽  
Shuxia Yuan ◽  
Yu Yang ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Interfacial Polymerization ◽  
Silicone Oil ◽  
Optical Microscope ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Oil Emulsion ◽  
Factors Affecting ◽  
Healing Agent ◽  
Water In Oil Emulsion

AbstractHealing agent microcapsules have been used to realize self-healing for polymeric composites. In this work a novel kind of microcapsules encapsulating ethylenediamine (EDA) with epoxy resin as shell material were prepared by interfacial polymerization technology. The oil phase was epoxy resin prepolymer and carbon tetrachloride, and the water phase was EDA and deionized water. Under the action of emulsifier, a stable water-in-oil emulsion was formed. Then the emulsion was added to dimethyl silicone oil, stirred and dispersed, to prepare microcapsules. In addition, the factors affecting the preparation of microcapsules were studied. In this study, Fourier transform infrared(FTIR) was carried out to demonstrate the chemical structure of ethylenediamine microcapsules. Optical microscope(OM) and scanning electron microscope(SEM) were used to observe the morphology of microcapsules. Thermogravimetric analysis and differential scanning calorimetry were done to investigate the thermal properties of microcapsules. Permeability experiment and isothermal aging test were executed to verify the environment resistance of microcapsules. Results showed that EDA was successfully coated in epoxy resin and the microcapsule size was in the range of 50~630 μm. The synthesized microcapsules were thermally stable below 75 °C and perfect permeability resistance to ethanol solvent.

scholarly journals Dual Monitoring of Cracking and Healing in Self-healing Coatings using Microcapsules Loaded with Two Fluorescent Dyes

2019 ◽  
Author(s):  
Young Kyu Song ◽  
Tae Hee Lee ◽  
Jin Chul Kim ◽  
Kyu Cheol Lee ◽  
Sang Ho Lee ◽  
...  
Keyword(s):  
Solid State ◽  
Fluorescent Dyes ◽  
Urea Formaldehyde ◽  
Uv Curing ◽  
Coating System ◽  
Self Healing ◽  
Matrix Resin ◽  
Healing System ◽  
Fluorescence Color ◽  
Healing Agent

We report the development of an extrinsic self-healing coating system that shows no fluorescence from the intact coating, yellowish fluorescence in cracked regions, and greenish fluorescence in healed regions, thus allowing the separate monitoring of cracking and healing of coatings. This fluorescence monitoring self-healing system consisted of a top coating, an epoxy matrix resin containing mixed dye-loaded in single microcapsule. The dye-loaded microcapsules consisted of a poly(urea-formaldehyde) shell encapsulating a healing agent containing MAT-PDMS and styrene, a photo-initiator and a mixture of two dyes, one that fluoresces only in the solid state (DCM) and a second that fluoresces dramatically increased in the solid than solution state (4-TPAE). A mixture of the healing agent, photo-initiator and the two dyes was yellow due to fluorescence from DCM. On UV curing of this mixture, however, the color changed from yellow to green and the fluorescence intensity increased due to fluorescence from 4-TPAE in the solid state. When a self-healing coating embedded with microcapsules containing the DCM/4-TPAE dye mixture was scratched, the damaged region exhibited a yellowish color that changed to green after healing. Thus, the self-healing system reported here allows the separate monitoring of cracking and healing based on changes in fluorescence color.

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