• Title/Summary/Keyword: Grafting

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Radiation-Induced Grafting of Acrylic Acid onto Cellulose : I. Graft Polymerization of Acrylic Acid onto Radiation-Peroxidized Cellulose (셀롤로오스에 아크릴산의 방사선 그라프트 반응: I. 과산화물에 의한 그라프트반응)

  • Kwon, Oh Hyun;Nho, Young Chang;Yang, Hyun Soo
    • Applied Chemistry for Engineering
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    • v.8 no.6
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    • pp.934-938
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    • 1997
  • Acrylic acid was grafted onto the peroxidized cellulose which was stored at room temperature for 20 days after ${\gamma}$-ray irradiation in air. The effect of acids and metallic salts on the grafting yields was determined. The addition of both the acid and metallic salt was found to accelerate the grafting yield much more than the only metallic salt, and the addition of $FeSO_4{\cdot}7H_2O$ led to much higher grafting yield than that of $CuSO_4{\cdot}5H_2O$. The effect of acid on the grafting yield increased by the order $H_2>SO_4>HCl>HNO_3>CH_3COOH$. With the addition of $H_2SO_4$, the grafting yield rapidly increased up to $7{\times}10^{-2}$M, and then levelled off.

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Hydrophilization of a Porous Polytetrafluoroethylene Supporter by Radiation Grafting Poly(Acrylonitrile-co-Sodium Allylsulfonate) (Acrylonitrile/Sodium Allylsulfonate 공중합체 방사선 접목을 이용한 다공성 Polytetrafluoroethylene 지지체의 친수화)

  • Park, Byeong-Hee;Sohn, Joon-Yong;Yoon, Ki-Suk;Shin, Junhwa
    • Polymer(Korea)
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    • v.38 no.3
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    • pp.293-298
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    • 2014
  • We prepared hydrophilic porous supporters for the reinforced composite fuel cell membrane by radiation grafting of acrylonitrile (AN) and hydrophilic sodium allylsulfonate (SAS) into a porous polytetrafluoroethylene (PTFE) supporter. The physicochemical properties of the supporters prepared under various reaction conditions such as molar ratio of SAS/AN, monomer concentration, and irradiation dose were evaluated. FTIR was utilized to confirm the successful introduction of SAS/AN copolymer chains into the porous PTFE. The pores of the porous PTFE film were found to be decreased with an increase in the degree of grafting by using FE-SEM and gurley number. Furthermore, by analyzing the degree of grafting, contact angle, and TBO (toluidine blue O) uptake, the hydrophilicity of the prepared supporters was found to increase with an increase in the degree of grafting.

CASES REPORT OF CLEFT ALVEOLUS REPAIR WITH PMCB GRAFT (치조골 파열환자의 자가망상골 이식을 이용한 치험례)

  • Lee, Dong-Keun;Choi, Seong-Hoon;Chung, Hyung-Bai
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.13 no.1
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    • pp.9-15
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    • 1991
  • The cleft alveolus occurs about 75% of cleft lip and palate patients. The purpose of bone grafting is improve the maxillary growth, rehabilitation of continuty of maxillary arch and providing bone for periodontal support for unerupted teeth. The bone grafting for alveolar cleft defect repair are classsified; primary bone grafting, early secondary bone grafting secondary bone grafting and late secondary bone grafting. In this article, we reported the cases of PMCB grafts for repair of the alveolar clefts showed potential benifit to the patient to induce a normal maxillary growth and providing bone foor periodontal support of unerupted teeth.

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Radiation Induced-Grafting of Acrylic Acid onto Polyvinyl Chloride Fibers

  • Park, Jae-Ho;Lee, Chong-Kwang
    • Nuclear Engineering and Technology
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    • v.8 no.2
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    • pp.89-99
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    • 1976
  • The grafting of acrylic acid in aqueous solution to polyvinyl chloride fibers tab been studied in the presence of ferrous, ferric, and cupric salts, The mutual irradiation technique was adopted using a Co-60 source or a Van do Graaff accelerator. The grafting and homopolymerization were suppressed by the cations. Particularly the grafting was suppressed by the cations in the following order of effectiveness : $Cu^{2+}$>$Fe^{2+}$>$Cu^{3+}$. The rate of grafting (in %/hr) was proportional to the 0.76th power of the dose rate over the range from 8.5f $10^3$ rad/hr to $1.4\times10^5$ rad/dr. The apparent activation energy for the grafting was determined to be 6.1 Kcal/mole between $25^{\circ}$ and $75^{\circ}C$ for the mixture of AA-HaO-$(CH_2Cl)_2$, containing Mohr's salt, $4\times10^{-3}$ mole/l. The increase of the grafting was observed when total dose and dose intensity were raised, or when ethylene dichloride as a swelling agent was saturated in the monomer mixture. The grafted polyvinyl chloride fibers showed considerable improvement in moisture regain, heat shrinkage, and melting properties, but tensile properties were not significantly affected by grafting.

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Development of an Automatic Grafting Robot for Fruit Vegetables using Image Recognition (영상인식 기술 이용 과채류 접목로봇 개발)

  • Kang, Dong Hyeon;Lee, Si Young;Kim, Jong Koo;Park, Min Jung;Son, Jin Kwan;Yun, Sung-Wook
    • Journal of Bio-Environment Control
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    • v.28 no.4
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    • pp.322-327
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    • 2019
  • This study was conducted to improve the performance of automatic grafting robot using image recognition technique. The stem diameters of tomatoes and cucumber at the time of grafting were $2.5{\pm}0.3mm$ and $2.2{\pm}0.2mm$ for scions and $3.1{\pm}0.7mm$ and $3.6{\pm}0.3mm$ for rootstocks, respectively. The grafting failure was occurred when the different height between scions and rootstocks were over 4 mm and below 2 mm due to the small contact area of both cutting surface. Therefore, it was found that the height difference at the cutting surface of 3 mm is appropriate. This study also found that grafting failure was occurred when the stem diameters of both scions and rootstocks were thin. Therefore, it was suggested to use at least one stem with thicker than the average stem diameter. Field survey on the cutting angle of stems by hand were ranged from 13 to 55 degree for scions and 15 to 67 degree for rootstocks, respectively, which indicates that this could cause the grafting failure problem. However, the automatic grafting robot developed in this study rotates the seedlings 90 degree and then the stems are cut using a cutting blade. The control part of robot use all images taken from grafting process to determine the distance between a center of both ends of stem and a gripper center and then control the rotation angle of a gripper. Overall, this study found that The performance of automatic grafting robot using image recognition technique was superior with the grafting success rates of cucumber and tomato as $96{\pm}3.2%$ and $95{\pm}4%$, respectively.

Studies on the Graft Polymerization of Polyethyleneglycol Monomethacrylate onto Chitosan and Drug(Vitamin B12) Permeation Behavior (키토산과 폴리에틸렌글리콜 모노메타크릴레이트의 그라프트중합과 약물(Vitamin B12)방출에 관한 연구)

  • Chung, Joo-Eun;Chung, Byung-Ok;Chang, Byung-Kwon;Choi, Kyu-Suk
    • Applied Chemistry for Engineering
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    • v.5 no.3
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    • pp.524-536
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    • 1994
  • Chitosan is known to be a good biocompatible natural polymer. Polyethyleneglycol monomethacrylates(PEGM) were grafted onto chitosan and their reaction conditions and properties of the graft polymers obtained were estimated. Using ceric ammonium nitrate(CAN) as the initiator, the optimum condition for graft polymerization was determined amount of the initiator and monomer concentrations and reaction time. Grafting yields such as total conversion, the percentage of grafting and the efficiency of grafting were calculated and examined the optimum reaction condition for high grafting yields. The percentage of grafting and total conversion were maximum at condition that the concentration of initiator was $4{\sim}5{\times}10^{-3}M$, the concentration of monomer was 0.5~0.6M, the reaction time was 2~3 hours and the reaction temperature was about $40^{\circ}C$. Thermal characteristics, solubility for chitosan solvents and inherent viscosity of synthesized graft copolymers were investigated. In high initiator concentration, characteristics of chitosan were greatly diminshed. In case of inherent viscosities, chitosan-g-PE-90 was 2.81 dl/g, chitosan-g-PE-200, 3.01dl/g and chitosan-g-PE-350, 4.93dl/g. And a tendency of viscosity increase depending on the length of ethylene oxide residue was confirmed. Degree of swelling, tensile strength, elongation of membrane prepared from graft copolymers were determined. Properties of graft copolymers were affected by percentage of grafting and length of ethylene oxides residue in polyethylene glycol monomethacrylates. Tensile strength, elongation and degree of swelling of graft copolymers were remarkably improved than chitosan. As percentage of grafting increased, the amount of drug permeation was also increased.

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The Clinical Study on Shrinkage Rate of Graft Following Connective Tissue Autografts (결합조직 이식술후 이식편의 수축률에 관한 임상적 연구)

  • Kim, Young-Jun;Lim, Sung-Bin;Chung, Chin-Hyung
    • Journal of Periodontal and Implant Science
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    • v.30 no.3
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    • pp.639-650
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    • 2000
  • The purpose of this study was to evaluate clinical changes in graft size after treatment with connective tissue autograft in human. 40 premolar teeth in 23 patients having the following mucogingival problemswere selected. The width of extension, attached gingiva including free marginal gingiva, width of transplant and clinical sulcus depth were measured at the initial examination, 2, 12 and 24 weeks following the connective tissue autograft and free gingival autograft. The change of width of extension, attached gingiva including free marginal gingiva, width of transplant and clinical sulcus depth according to healing process in both graft procedures was statistically analyzed by ANOVA test and independent ttest using SPSS program. The results were as follows : 1. The change of keratinized gingiva in both grafting procedures was increased significantly at 24 weeks post-op. 2. The clinical sulcus depth exhibited no marked changes throughoutthe entire investigation in both grafting procedures. 3 . After 12 weeks, no dimensional variation was seen in graft size in both grafting procedures. 4. Shrinkage differs significantly in both grafting procedures. From the day of graft to 24 weeks after surgery the percentages of shrinkage were connective tissue autograft 55% and free gingival autograft 29%.

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Synthesis and Their Properties of PP Graft Copolymers by E-beam Radiation and Vapor Phase Reaction (전자선 조사 기상 반응에 의한 PP 기재 공중합체의 합성과 특성)

  • 황택성;박진원;이재천
    • Polymer(Korea)
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    • v.26 no.3
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    • pp.287-292
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    • 2002
  • Graft copolymerization of styrene and glycidyl methacrylate (GMA) to the peroxidized polypropylene (PP) fabric with E-beam in $O_2$ atmosphere was carried out in vapor phase with benzoyl peroxide (BPO) as an initiator. The degree of grafting of copolymers was increased with the increase of the reaction temperature and the highest degree of grafting was obtained at $70^{\circ}C$ with styrene, and at $80^{\circ}C$ with GMA. The highest degree of grafting of styrene grafted PP according to reaction time was higher than that of GMA grafted PP. In vapor phase graft polymerization, the degree of grafting of copolymers according to water composition in monomer mixture was effected by the boiling temperature of monomers.

An investigation on anode electrocatalysts using grafting method for improvement of DMFC performances (Grafting 방법을 이용한 직접메탄올연료전지 애노드 촉매의 성능향상에 관한 연구)

  • Park, Jung-Bae;Han, Kook-Il;Kim, Ha-Suck
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.413-416
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    • 2006
  • PtRu catalyst is most widely used as anode catalyst for a direct methanol fuel cell(DMFC). To promote the efficiency of the catalysts, it Is important to increase the triple phase boundary. In this study, we have tried to increase the triple phase boundaries in preparing electrocatalysts of the fuel cells, based on the process of grafting a proton-conducting agent onto the catalyst This grafted proton-conducting agent can act as an ionomer like Nafion, currently widely used ionomer. First, we have prepared the 80wt% PtRu/Ketjen Black electrocatalyst by an improved colloidal method. And, we have grafted methylsulfonate groups $(-CH_2SO_3H)$ into the catalyst as proton-conducting agents. As results of cyclic voltammety and single cell test of the membrane electrode assembly (MEA), we can conclude that the activity of the grafted electrocatalysts is superior to that of conventional ones, in performance of DMFCs. For our further study, we will investigate the optimum ratio of catalyst/grafted proton conduct Ing agent with maximum performance of a DMFC.

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