• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.05a
• /
• pp.65-68
• /
• 2002

This study dealt with autonomic microcapsules with the healing agent for damage repair of the composite structures. Autonomic microcapsules were made of a urea-formaldehyde resin for shell of microcapsule and a DCPD for the healing agent. Thermal analysis was conducted by using a DSC and a TGA for the healing agent, microcapsules without the healing agent, and microcapsules with the healing agent. According to the results, autonomic microcapsules were verified to be so thermally stable that the healing agent was kept inside the microcapsule until the shell of microcapsules were burned out.

• Composites Research
• /
• v.15 no.2
• /
• pp.32-39
• /
• 2002

This study focused on the introduction of processing procedure for microcapsules loaded with the healing agent and then microcapsules with the healing agent were manufactured by experiments. The DCPD (dicyclopentadiene) was used for the healing agent and the shell of microcapsules was consisted of urea-formaldehyde resin. The magnitude and the site distribution of microcapsules were measured by a particle size analyzer using laser diffraction technique. Thermal analysis was conducted by using a DSC fur the healing agent, microcapsules without the healing agent, and microcapsules with the healing agent. Also thermal stability was investigated by using a TGA under continuous and isothermal heating conditions far the healing agent, microcapsules without the healing agent, microcapsules with the healing agent. According to the results. microcapsules with the healing agent were verified to be so thermally stable that the healing agent could not evaporate until the shell of microcapsules were burned.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.309-314
• /
• 2004

This study focused on the introduction of damage repair for polymeric composite carbody. called selfing tech-healinique. using microcapsules loaded with the healing agent The manufacturing process for microcapsules with the healing agent was introduced and tile characteristics of microcapsules manufactured by varying with various manufacturing process variables were evaluated. The DCPD was used for the healing agent and microcapsules were made of urea-formaldehyde resin. The magnitude and the size distribution of microcapsules were measured by a particle size analyzer using laser diffraction technique. Thermal stability was investigated by using a TGA under continuous and isothermal heating conditions for the healing agent. microcapsules without the healing agent. microcapsules with the healing agent.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.626-629
• /
• 2004

Recently, the self-healing technique is being investigated to repair the damaged polymeric composites by the use of microcapsules with the healing agent. This technique can obtains both the damage detection and the damage repair simultaneously over the converntional repairing techniques. In this study, the effects of the catalyst ratio to the healing agent and thermal characteristics to the mixtures of healing agent are investigated through single lap shear tests and DSC. The Healing agents such as DCPD, ENB, and their mixtures are considered and Grubb's catalyst is used as a catalst.

• Journal of the Korean Ceramic Society
• /
• v.54 no.6
• /
• pp.492-498
• /
• 2017

A thermal barrier coating (TBC) with self-healing property for cracks was proposed to improve reliability during gas turbine operation, including structural design. Effect of healing agent on crack propagation behavior in TBCs with and without buffer layer was investigated through furnace cyclic test (FCT). Molybdenum disilicide ($MoSi_2$) was used as the healing agent; it was encapsulated using a mixture of tetraethyl orthosilicate and sodium methoxide. Buffer layers with composition ratios of 90 : 10 and 80 : 20 wt%, using yttria stabilized zirconia and $MoSi_2$, respectively, were prepared by air plasma spray process. After generating artificial cracks in TBC samples by using Vickers indentation, FCTs were conducted at $1100^{\circ}C$ for a dwell time of 40 min., followed by natural air cooling for 20 min. at room temperature. The cracks were healed in the buffer layer with the healing agent of $MoSi_2$, and it was found that the thermal reliability of TBC can be enhanced by introducing the buffer layer with healing agent in the top coat.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.93-96
• /
• 2001

Structural polymer composites are susceptible to damage in the form of cracks, which form deep within the structure where detection is difficult and repair is almost impossible. A recent methodology for the damage repair of polymer composites using the self-healing technique is reported. The polymerization of the healing agent is triggered by contact with an embedded catalyst, being necessary to damage repair of polymer composites. For this purpose, the self-healing concept is introduced and the manufacturing process of microcapsule with the healing agent is briefly described. The polymerization between the healing agent and the catalyst is verified by the use of ESEM and IR spectroscopy. Finally the efficiency of the self-healing technique is investigated by measuring the critical load of TDCB specimen.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.435-436
• /
• 2006

This study focused on the introduction of the self healing technique for polymeric composites and evaluated the healing efficiency by the use of the interlaminar toughness fracture test. The DCPD (dicyclopentadiene) and ENB (5-ethylidene-2-norbornene) were used for the healing agent and the Grubbs' catalyst was used for the catalyst. According to the results, healing efficiency was found to be 37.9%, 22.3%, 26.3%, 22.8%, 30.8%, 30.8%, 33.0%, 33.4% for mode II fraction of 0%, 20%, 35%, 50%, 65%, 80%, 90%, 100%, respectively.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.340.1-340.1
• /
• 2002

Centella asiatica is an herbal plant used on different continents by diverse ancient cultures and tribal groups. Historically. the extract has been used as a wound healing agent, The extract has three different triterpenoid ingredients: asiaticoside. asiatic acid, and madecassic acid. It has been reported that its wound healing activity is associated with the modulation of collagen synthesis in the skin dermis. The wound healing property of the extract has led to its commercial introduction under the trade name, Madecrlssol. As part of our program toward the development of new wound healing agents. structere activity relationship (SAR) studies have been performed by modifying asiatic acid. In this communication. the SAR study of esiatic acid for the development of an efficient woind healing agent is reported.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.6
• /
• pp.138-143
• /
• 2023

In this study, the crack healing performance of each crack healing agent manufacturing method was analyzed by adding crack healing agents in the form of alginate gel and spore suspension inoculated with endospores of calcium carbonate-forming bacteria to mortar. In addition, by applying it to an full-scale structure in the form of a box-type culvert, we attempted to create an environment in which the developed crack healing agent can be applied not only to a laboratory environment but also to an actual field. The crack healing agent using the dry heat drying method showed crack healing performance, but in the case of the freeze drying method, many spores were killed by freeze hardening and therefore the crack healing performance was lost. As a result of SEM and XRD pattern analysis of the presumed crack healing material extracted from the crack of a full-scale structure, it was found to be calcite, one of the calcium carbonate crystals produced by microorganisms applied to the crack healing agent. In conclusion, it was found that the crack healing by microorganisms can be implemented in a real structure.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.6
• /
• pp.579-587
• /
• 2015

In this paper, microencapsulated healing agent was embedded in the polymer matrix to obtain self healing properties. Microencapsulation of methacrylate using polyurea-formaldehyde as a shell material and studied the effect of agitation rate on capsule characteristics such as size, shell thickness, and surface morphology. The formation of microcapsules was confirmed by FTIR and TGA, and capsule characteristics were studied by optical microscopy and SEM. The self-healing effect was evaluated using permeability measurements and further confirmed by surface analytical tools including optical microscope. According to the experimental results, the microencapsulated healing system has the self-heaing ability for artificial cracks.