• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.190-193
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• 2004

Two different diene monomers [dicyclopentadiene (DCPD) and 5-ethylidene-2-norbomene (ENB)] as self­healing agent for polymeric composites were microencapsuled by in-situ polymerization of urea and formaldehyde. The healing agents were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Exothermic reaction and glass transition temperature from DSC and storage modulus (G') and tan $\delta$ from DMA curves were analyzed for the samples cured for 5 min and 24 h in the presence of different amounts of catalyst. Micorcapsules were successfully formed for both diene monomers. Microcapsules containing the healing agent were manufactured and its thermal properties were characterized by thermo gravimetric analysis (TGA). Optical microscope (OM) and particle size analyzer (PSA) were employed to observe morphology and size distribution of microcapsules, respectively. Comparison of the two self-healing agents and their microcapsules with the two was made in this study.

• Elastomers and Composites
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• 제50권3호
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• pp.167-174
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• 2015

Anionic epoxy compound was synthesized and added to asphalt aiming to prepare self-healing asphalt. Epoxy-modified asphalt showed excellent modification effect and healing effect as well. The results revealed that with 5% addition of polymer the tensile strength, impact strength and complex shear modulus of the polymer-modified asphalt increased by 65%. 64% and 35%, respectively. It seems that high interaction occurs between polymer and asphalt matrix. Self-healing efficiency of the polymer-modified asphalt based on tensile strength showed 100%, comparing to 79% of straight asphalt. In impact experiment the polymer-modified asphalt showed 99% of healing efficiency, comparing to 77% of straight asphalt. In rheological experiment the polymer-modified asphalt showed 103% of healing efficiency, comparing to 72% of straight asphalt. It appears that the ionic bonding existing in epoxy polymers contributed to high values of self-healing efficiency. The polymer which has high intermolecular force fills the crack of the asphalt, pulling the opponent side each other, and so the original properties were restored.

• 한국정밀공학회지
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• 제18권4호
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• pp.135-141
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• 2001

An experimental study to find the effect of processing parameters for self-healing microcapules is performed. These microcapsules can be applied to accomplish the healing of delamination damage in woven E-glass/epoxy composites. This paper introduces the self-healing concept and presents a method for solving the microcapsule size and shape. Additionally, processing parameters are varied during the formation of microcapsules and these capsules are observed through optical microscope. To obtain thermogravimetric(TG) curve for the manufactured microcapsules, TGA tests are executed. From these results, the best processing conditions for the formation of capsules are found as follows: (1) temperature of solution $ 50^{\circ}C$, (2) potential of hytdrogen(pH) 3.5ppm, and (3) agitation 500~600rpm.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.262-265
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• 2004

This study focused on the introduction of the self-healing technique for polymeric composites and evaluated the healing efficiency through the interlainar fracture toughness tests. The DCPD and ENB were used for a healing agent and the Grubbs' catalyst as a catalyst. The healing efficiency was evaluated by the use of mode I and the mode n fracture toughnesses. According to the results, the DCPD-ENB mixture with a suitable ratio revealed better healing efficiency than DCPD only.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.119-126
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• 2015

Among the various human growth factors, epidermal growth factor (hEGF, consisting of 53 amino acids) has various effects on cell regeneration, stimulation of proliferation, migration of keratinocytes, formation of granulation tissues, and stimulation of fibroblast motility, which are important for wound healing. Owing to their multiple activities, EGFs are used as pharmaceutical and cosmetic agents. However, their low productivity, limited target specificity, and short half-life inhibit their application as therapeutic agents. To overcome these obstacles, we fused the collagen-binding domain (CBD) of Vibrio mimicus metalloprotease to EGF protein. About 18 or 12 amino acids (aa) (of the 33 total amino acids), which were essential for collagen-binding activity, were combined with the N- and C-termini of EGF. We constructed, expressed, and purified EGF (53 aa)-CBD (18 aa), EGF (53 aa)-CBD (12 aa), CBD (18 aa)-EGF (53 aa), and CBD (12 aa)-EGF (53 aa). These purified recombinant proteins increased the numbers of cells in treated specimens compared with non-treated specimens and control hEGF samples. The collagen-binding activities were also evaluated. Furthermore, CBD-hybridized hEGF induced phosphorylation of the EGF receptor. These results suggested that these fusion proteins could be applicable as small therapeutic agents in wound tissue healing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.166-167
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• 2015

The purpose of this study is to examine the effect on drying shrinkage of self-healing epoxy-modified mortars(EPMMs) using expansive admixtures. The EPMMs are prepared with polymer-binder ratios of 0 and 10%, and tested for drying shrinkage and pore structure analysis. As a result, regardless of the expansion and swelling agent content, the drying shrinkage of the EPMMs is remarkably decreased than that of unmodified mortars. Also, the pore size distribution of the EPMMs is moved to smaller size in comparison with unmodified mortars. In this study, the EPMM with expansive agent 7.5% and swelling agent 2.5% is recommended as a optimal mix proportion for reduction of drying shrinkage.

• Composites Research
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• 제16권2호
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• pp.54-61
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• 2003

본 연구에서는 자가치료제가 저장된 마이크로캡슐의 제조공법을 소개하였으며 제조공정변수를 달리하여 제조된 마이크로캡슐의 특성을 입도분석기, 광학현미경, TGA 등을 통해 평가하였다. 이때 자가치료용 마이크로캡슐은 요소-포름알데히드 수지로 구성된 박막으로 되어 있으며 마이크로캡슐의 내부에는 자가치료제인 DCPD가 충전되어 있는 경우를 고려하였다. 마이크로캡슐의 제조공정변수로는 (1) 24시간. 40시간. 48시간, 60시간의 EMA copolymer 용해시간, (2) pH3.5, pH4.0, pH4.5의 수소이온농도, (3) 400rpm, 500rpm, 600rpm. 1000rpm의 교반속도, (4) $50^{\circ}$, $55^{\circ}$, $60^{\circ}$의 반응온도 등을 고려하였다. 연구결과에 따르면 마이크로캡슐의 입도분포는 교반속도에 따라 달라지며, EMA copolymer의 용해시간, 수용액에서의 수소이온농도 및 반응온도 등은 마이크로캡슐의 열안정성에 큰 영향을 미친다. 따라서 마이크로캡슐의 내부에 저장된 자가치료제의 증발을 억제할 수 있는 우수한 열안정성을 갖는 마이크로캡슐을 제조하기 위해서는 적절한 제조공정변수가 적용되어야 한다.

• Toxicological Research
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• 제16권3호
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• pp.211-219
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• 2000

The therapeutic effect of AS2-006A, a derivative of asiaticoside, has been studied and is being developed as a new wound-healing agent. In the present study, the general pharmacological effects on 1) central nervous system, 2) autonomic nervous system, 3) respiratory system, 4) gastrointestinal system. 5) cardiovascular system. and 6) urinary system were assessed in experimental animals and in in vitro models. 1. In vivo animal study: External applications of the 1 % gel ointment of AS2-006A to rats at the doses of 200. 600 or 2000 mg/kg body weight showed no observable pharmacological effects. The effects on the central nervous system were assessed by observation of behavior, hexobarbital-induced sleeping time, pentetrazole-induced convulsion assay, body temperature measurements, and observations on spontaneous activity and catalepsy. The gel ointment exhibited no effects on the cardiovascular system (i.e. blood pressure and heart rate), renal physiology (i.e. urine volume and electrolytes excretion) and gas-trointestinal physiology (i.e. intestinal charcoal propulsion and gastric mucosal irritation). 2. In vitro experiments: The effects of AS2-006A on the physiology of smooth and cardiac muscles were assessed. Muscle contractions were isotonically and isometrically measured in organ chambers using a physiograph. Cumulative additions of AS2-006A (10$^{-9}$ -10$^{-5}$ M) induced no changes in the tension of isolated guinea pig ileum and tracheal muscles. AS2-006A only slightly increased contractility of rat atrial and papillary muscles at 10$^{-2}$ M, which was not statistically different from control. These data showed that the gel ointment of AS2-006A could be externally applied as a wound-healing agent with no potential side effects.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.577-583
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• 2022

본 연구에서는 고로슬래그 미분말, 팽창재 및 무수석고로 이루어진 무기계 자기치유 소재를 사용하여 제조한 자기치유 모르타르의 특성을 조사하였다. 무기계 치유재료의 사용량이 다른 3종류의 자기치유 모르타르를 대상으로 압축강도를 측정하고 정수위 투수시험를 통하여 치유성능을 평가하였다. 치유성능 평가지표로 균열유도재령애 따른 치유율과 등가균열폭을 활용하였다. 자기치유 모르타르의 압축강도 발현, 치유재령에 따른 치유율 변화와 경제성을 고려하여 무기계 혼합재의 최적 사용량을 시멘트 질량 대비 20 %로 제안하였다.

• Toxicological Research
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• 제34권2호
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• pp.97-102
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• 2018

The objective of this study was to determine the oral wound healing effects of acai berry water extracts (ABWE) in rat oral mucosa. To estimate the anti-oxidative effects of ABWE, the contents of phenolic compounds, and DPPH (1,1-diphenyl-2-picryl hydrazyl) and ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) abilities were evaluated. Wound healing effects of ABWE were tested following 6-day exposure after induction of wound by applying 50% acetic acid to oral mucosa of Sprague-Dawley rats. Macroscopic and histopathological analyses were performed to determine wound healing effects of ABWE. Sodium fusidate (20 mg/g) was used as positive control. ABWE showed significantly high antioxidant effects in all assays, although its potency was weaker than the positive control. From day 3 after treatment, wound healing effects of ABWE were observed in oral mucosa. These wound healing effects were also consistent with histopathological evaluation results. Taken together, these results indicate that ABWE might have potential as an oral wound healing agent in the future.