scholarly journals Preparation and Self-Repairing Properties of Urea Formaldehyde-Coated Epoxy Resin Microcapsules

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yijuan Chang ◽  
Xingyu Qian
Keyword(s):  
Epoxy Resin ◽  
Deposition Time ◽  
Urea Formaldehyde ◽  
Coverage Rate ◽  
Core Material ◽  
Self Healing ◽  
Mass Ratio ◽  
Repair Rate ◽  
The Core ◽  
Five Factors

Urea formaldehyde resin-coated epoxy resin microcapsules were prepared by two-step in situ polymerization. The effects of five factors on the yield, coverage rate, repair rate, and morphology of the microcapsules were investigated by five factors and four levels of orthogonal test. These five factors were the mass ratio of the core to the wall material (Wcore:Wwall), the mass ratio of the emulsifier to the core material (Wemulsifier:Wcore), stirring rate, deposition time, and mass ratio of the emulsifier solution to the core material (Wemulsifier solution:Wcore). The ideal technological level of microcapsule synthesis was determined. According to the results of the range and variance of yield, coverage rate, and repair rate, the comprehensive properties of microcapsules became ideal. At this time, the Wcore:Wwall was 0.8 : 1, Wemulsifier:Wcore was 1 : 100, stirring rate was 600 r/min, deposition time was 32 h, and Wemulsifier solution:Wcore was 8 : 1. When the concentration of microcapsules in the epoxy resin was 10.0%, the self-repair rate was the best and the repair rate was 114.77%. This study is expected to provide a reference value for the preparation of a microcapsule self-healing technology and lay a foundation for the subsequent development of self-healing materials.

scholarly journals Development and Performance Evaluation of Corrosion Resistance Self-Healing Coating

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Akshya Kumar Guin ◽  
Suryakanta Nayak ◽  
Manish Kumar Bhadu ◽  
Veena Singh ◽  
Tapan Kumar Rout
Keyword(s):  
Corrosion Resistance ◽  
Performance Evaluation ◽  
Urea Formaldehyde ◽  
Sol Gel ◽  
Core Material ◽  
Self Healing ◽  
Nacl Solution ◽  
The Core ◽  
Steel Protection ◽  
And Performance

Polymer based nanocapsule was developed using core-cell approach, where the core material was methyl diphenyl diisocyanate and the cell material was urea-formaldehyde. The synthesized capsules of 100 to 800 nm size were incorporated into sol-gel matrix to prepare a final coating for steel protection. This coating was found protecting the steel at the damage or crack locations in 3.5% NaCl solution. SEM micrographs confirmed healing of the coating at the damage or crack points.

scholarly journals Effect of Microcapsules with Waterborne Coating as Core Material on Properties of Coating for Tilia Europaea and Comparison with Other Microcapsules

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3167
Author(s):  
Xiaoxing Yan ◽  
Yu Tao ◽  
Xingyu Qian
Keyword(s):  
Performance Enhancement ◽  
Urea Formaldehyde ◽  
Impact Resistance ◽  
Core Material ◽  
Wall Material ◽  
Waterborne Coating ◽  
Self Healing ◽  
Mass Ratio ◽  
Waterborne Coatings ◽  
New Research

Urea formaldehyde was used as wall material and waterborne coatings as a core material to prepare microcapsules. So as to explore the influence of mass ratio of core to shell, reaction temperature and standing time on the performance of microcapsules, the orthogonal test of three factors and two levels was put into effect. The orthogonal experimental results showed the mass ratio of core to shell was the most important factor. With the increase of the mass ratio of core to shell, the output and clad ratio of microcapsules increased first and then decreased. The microcapsule with the mass ratio of core to shell of 0.67:1 had better appearance, output, and encapsulation performance. The optical properties of waterborne wood coating with the microcapsules of waterborne coating as core materials did not decrease significantly, while the hardness, impact resistance, and toughness were improved. At the same time, the microcapsules have a certain self-repairing effect on coating micro-cracks. Compared with the properties of waterborne coatings with other microcapsules, the coating with waterborne coating as core material has better comprehensive performance. The results provide a new research idea for the performance enhancement and self-healing of wood waterborne coating.

Study on the Curing Kinetics of Epoxy Resin in Self-Healing Microcapsules with Different Shell Material

2011 ◽  
Vol 306-307 ◽  
pp. 658-662 ◽  
Author(s):  
Xiao Mei Tong ◽  
Min Zhang ◽  
Ming Zheng Yang
Keyword(s):  
Epoxy Resin ◽  
Urea Formaldehyde ◽  
Curing Kinetics ◽  
Core Material ◽  
Self Healing ◽  
Curing Process ◽  
Shell Material ◽  
Decomposition Products ◽  
The Stability ◽  
Kinetics Of

The curing process of self-healing microcapsules containing epoxy resin was studied with different shell material such as Poly (urea-formaldehyde), poly (melamine-urea-formaldehyde), Poly (urea-formaldehyde) modified by polyvinyl alcohol, and Poly (urea-formaldehyde) modified by phenol, respectively. The activation energy (ΔE) and the reaction order (n) have been obtained based on Kissinger method, Crane theory and Arrhenius equation. The results showed that: the curing process of epoxy resin as core material in self-healing microcapsules becomes more difficult compared with non-microencapsulated. The stability of shell material impacts on the cure process of core material. The resulting decomposition products of shell materials may participate in the curing reaction. So choosing suitable shell material is particularly important to self-healing microcapsules.

scholarly journals Fibers Networks as a New Type of Core Material. Processing and Mechanical Properties

2009 ◽  
Vol 1188 ◽  
Author(s):  
Laurent Mezeix ◽  
Christophe Bouvet ◽  
Serge Crézé ◽  
Dominique Poquillon
Keyword(s):  
Epoxy Resin ◽  
Carbon Fibers ◽  
Sandwich Panels ◽  
Open Architecture ◽  
Core Material ◽  
Cross Linking ◽  
Damping Capacity ◽  
The Core ◽  
Water Accumulation ◽  
Core Materials

AbstractMany different sandwich panels are used for aeronautical applications. Open and closed cell structured foam, balsa wood or honeycomb are often used as core materials. When the core material contains closed cells, water accumulation into the cell has to be taken into account. This phenomenon occurs when in service conditions lead to operate in humidity atmosphere. Then, water vapor from air naturally condenses on cold surfaces when the sandwich panel temperature decreases. This water accumulation might increase significantly the weight of the core material. Core with a ventilated structure helps to prevent this phenomenon. Periodic cellular metal (PCM) has been motivated by potential multifunctional applications that exploit their open architecture as well as their apparent superior strength and stiffness: pyramidal, lattice, Kagome truss or woven. One of the drawbacks of these materials is the expensive cost of the manufacturing. Recently, a novel type of sandwich has been developed with bonded metallic fibers as core material. This material presents attractive combination of properties like high specific stiffness, good damping capacity and energy absorption. Metal fibers bonded with a polymeric adhesive or fabricated in a mat-like form consolidated by solid state sintering. Entangled cross-linked carbon fibers have been also studied for using as core material by Laurent Mezeix. In the present study, ventilated core materials are elaborated from networks fibers. The simplicity of elaboration is one of the main advantages of this material. Multifunctional properties are given by mixing different sorts of fibers, by example adding fibers with good electrical conduction to give electrical conductivity properties. In this study network fibers as core material are elaborated using carbon fibers, glass fibers and stainless steel fibers. In aeronautical skins of sandwich panels used are often carbon/epoxy prepreg, so epoxy resin was used to cross-link fibers. The core thickness was chosen at 30 mm and fibers length was chosen at 40 mm. Entanglement, separation of filaments and cross-linking are obtained in a specific blower room. Fibers are introduced in the blower room, compressed air is applied and in same time epoxy resin is sprayed. Indeed one of the sandwich core material properties required is low density, so yarns size need to be decreased by separating filaments. Network fibers are introduced in a specific mould and then are compressed. The density obtained before epoxy spaying is 150 kg/m3. Finally samples are polymerized at 80°C for 2 hours in a furnace under laboratory air. Compressive behavior is study to determinate the influence of fibers natures and the effect of cross-linking. Reproducibility is also checked.

scholarly journals Preparation and Optimization of Waterborne Acrylic Core Microcapsules for Waterborne Wood Coatings and Comparison with Epoxy Resin Core

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2366 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yu Tao ◽  
Xingyu Qian
Keyword(s):  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Paint Film ◽  
Bath Temperature ◽  
Water Bath ◽  
Core Material ◽  
Wall Material ◽  
Formaldehyde Resin ◽  
The Core ◽  
Resin Core

Microcapsules were prepared by in situ polymerization with urea formaldehyde resin as the wall material and Dulux waterborne acrylic acid as the core material. The effects of the core–wall ratio, water bath temperature and depositing time on the morphology, particle size, yield and encapsulation ratio of microcapsules were investigated by orthogonal experiment of three factors and two levels. The results showed that the core–wall ratio had the greatest influence on the performance of microcapsules. When the core–wall ratio was 0.58:1, the water bath temperature was 70 °C, and the depositing time was 5 d, the microcapsule performance was the best. With the increase in depositing time, the yield of microcapsule particles increased gradually, and the microcapsules appeared to show an adhesive phenomenon. However, the long-term depositing time did not lead to complete deposition and agglomeration of microcapsules. When 10.0% concentration of the waterborne acrylic microcapsules with 0.58:1 of core–wall ratio was added to the coatings, the mechanical and optical properties of the coatings did not decrease significantly, but the elongation at break increased significantly. Therefore, this study offers a new prospect for using waterborne acrylic microcapsules to improve the toughness of waterborne paint film which can be cured at room temperature on a wood surface.

Synthesis and Self-Healing Mechanism of Self-Healing Epoxy Microcapsule Materials

2020 ◽  
Vol 842 ◽  
pp. 3-9
Author(s):  
Zhuo Ni ◽  
Zhen Guo ◽  
Yu Hao Lin
Keyword(s):  
Epoxy Resin ◽  
Interfacial Polymerization ◽  
Curing Temperature ◽  
Future Research ◽  
Self Healing ◽  
Practical Applications ◽  
The Core ◽  
Good Surface ◽  
Core Content ◽  
Wall Materials

Self-healing epoxy resin microcapsules are prepared by interfacial polymerization, in which the core materials are epoxy resin, the wall materials are constructed with triethylenetetramine and the epoxy resin. The orthogonal experimental L9(34) are designed to investigate the influence of emulsifier dosage, hardener dosage, curing temperature and hardener adding rate on the core content and storage life of epoxy resin microcapsule. Scanning electron microscope is used to characterize surface topography and distribution. Fourier transform infrared spectroscopy is used to study reaction mechanism of the microcapsule wall materials, respectively. The results indicate that when the dosage of emulsifier is 1.2%, the dosage of hardener is 1.2%, the hardener droplets adding rate is 1.2 g/h and the curing temperature is 50°C, the prepared microcapsules with a high level of core content are spherical in shape with good surface compactness and dispersibility. Future research may focus on improving microcapsule storage stability and the obstacles encountered in practical applications.

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.

Influence of synthetic conditions on the performance of melamine–phenol–formaldehyde resin microcapsules

2018 ◽  
Vol 31 (2) ◽  
pp. 197-210 ◽  
Author(s):  
Zun-Xiang Hu ◽  
Xiang-Ming Hu ◽  
Wei-Min Cheng ◽  
Wei Lu
Keyword(s):  
Particle Size ◽  
Epoxy Resin ◽  
Phenol Formaldehyde ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Average Particle ◽  
Mass Ratio ◽  
Shell Mass ◽  
The Core ◽  
Resin Core

Melamine (M), phenol (P) and formaldehyde (F) were used as raw materials to synthesize a melamine–phenol–formaldehyde resin (MPF) which was used as shell material to prepare a self-healing microcapsule with E-51 epoxy resin as the core, via in situ polymerization. Fourier transform infrared spectroscopy, environmental scanning electron microscopy and laser particle size analysis were used to characterize the surface morphology, structure and properties of the microcapsule. The influence of the reaction conditions on the properties of the microcapsule was investigated by orthogonal testing. The mass ratio between the MPF shell and the epoxy resin core was found to be 1.2:1.0, optimum pH for shell formation was found to be 3, the emulsification speed was 800 r/min, the acidification speed was 400 r/min and the acidification temperature was 60°C. Under these conditions, the prepared microcapsules are regular and spherical with a smooth, dense surface and uniform particle size with a normal distribution. The microcapsules remained well dispersed and did not aggregate. The orthogonal test revealed that the average particle size and yield of the microcapsules are mainly determined by the core/shell mass ratio, whereas the reaction temperature had a greater impact on the core content of the microcapsules. Although the best microcapsule samples showed poor anti-permeability in ethanol, they exhibited good thermal, isothermal and storage stabilities. This indicates that they may be stored at a constant temperature.

Preparation and Repeated Repairability Evaluation of Sunflower Oil-Type Microencapsulated Filling Materials

2020 ◽  
Vol 20 (3) ◽  
pp. 1554-1566 ◽  
Author(s):  
Xiaoyong Tan ◽  
Jiupeng Zhang ◽  
Dong Guo ◽  
Guoqing Sun ◽  
Yingying Zhou ◽  
...  
Keyword(s):  
Particle Size ◽  
Sunflower Oil ◽  
Urea Formaldehyde ◽  
Core Material ◽  
Wall Material ◽  
Formaldehyde Resin ◽  
Particle Sizes ◽  
Self Healing ◽  
Filling Materials ◽  
Oil Type

Cracks are the main challenges for asphalt pavement, which should be timely repaired. One of the most commonly used repairing methods is to fill the binding materials into cracks, but the repeated repairing ability is insufficient. The self-healing microcapsule technologies provide the potentials for enhancing the repeated repairing ability of filling materials. Therefore, the microcapsule core material was selected from sunflower oil in this study, and the capsular wall material was selected from melamine-urea-formaldehyde resin, which was used to prepare the microcapsule by using in-situ polymerization method. Three kinds of microcapsules with different particle sizes were prepared by adjusting the emulsifier dosage and core wall ratio. The microstructure, molecular structure, thermal stability, and dispersion features were further studied, and the effects of microcapsules with different particle sizes on the repeated repairability of the filling materials were evaluated via the fatiguerepair-fatigue test. In addition, the traditional regenerative microcapsules were compared to determine the optimal particle size range for sunflower oil microcapsules. According to the experimental research, it was thus concluded that the emulsion droplet size distribution was most concentrated when the emulsifier content was 0.7%; and when the core-wall ratio was 1.3:1, the microcapsules had uniform particle size and good dispersion effect. When the microcapsule emulsification rate was 900 rpm and microcapsule content was 2%, then the repeated repair effect for the microcapsule crack filling materials was optimal. The sunflower oil type microcapsule therefore meets the filling temperature requirement for the filler.

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