• Title/Summary/Keyword: polymerization degree

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COMPARISON OF MECHANICAL PROPERTIES IN 4 INDIRECT COMPOSITE RESIN (4종의 간접법용 복합 레진의 기계적 특성 비교)

  • Kim, Kil-Soo;Yoon, Tae-Ho;Song, Kwang-Yeob;Ahn, Seung-Geun
    • The Journal of Korean Academy of Prosthodontics
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    • v.45 no.1
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    • pp.21-33
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    • 2007
  • Statement of problem: The esthetic component of dental care has become increasingly more important, while new tooth-colored materials are continually marketed. Various new indirect composite materials have been developed with required advantages. The most recent development in the indirect composites has been the introduction of the second-generation laboratory composite or poly-glass materials. They are processed by different laboratory techniques based on combinations of heat, pressure, vacuum and light polymerization. Although, second generation products became available in 1995, their characteristics and clinical performance have not been adequately investigated. Purpose: The aim of this study was to measure the mechanical properties of the second generation indirect resin system and compare these with an existing universal direct composite resin. Material and method: In this study four indirect composite material (Adoro LC, BelleGlass HP, Tescera, Synfony) were tested for flexural strength, wear resistance, hardness and their degree of conversion against Z250, a light cure direct composite. Results: Within the limitations of this study, the following conclusions were drawn: 1. From the abrasion wear result, Adoro showed the least volume loss while Synfony showed the greatest volume loss. Z250 and BelleGlass HP didn't show significant difference (p>0.05), but they showed significant difference with other groups (p<0.05). From the attrition wear, BelleGlass HP showed the least volume loss and it didn’t show significant difference with Tescera (p>0.05). While Synfony showed the greatest volume loss that it showed significant difference with other groups (p>0.05). 2. Mean values of flexural strength by means of three point bending test was in the order of Z250, Adoro, Belleglass HP, Tescera and Synfony. Mean elastic modulus was in the order of Z250, BelleGlass HP, Tescera, Adoro and Synfony. 3. The result of Vicker‘s microhardness value showed that significantly higher value in Z250 (p<0.05), and is in the order of BelleGlass HP, Tescera, Adoro and Synfony. 4. The degree of conversion measured by FT-IR showed significantly higher value in BelleGlass HP (p<0.05), and is in the order of Adoro, Synfony, Tescera and Z250. Conclusion: Significant differences were found in the flexural strength, wear resistance, hardness and their degree of conversion.

A Study on Synthesis and Hydrolysis of the Maleated Polyethylene Wax (무수말레인산으로 그라프트된 폴리에틸렌 왁스의 중합과 가수분해에 대한 연구)

  • Yu, Si-Won;Choi, Joong-So;Na, Jae-Sik
    • Clean Technology
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    • v.19 no.4
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    • pp.393-400
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    • 2013
  • In this study, Polyethylene wax, which was produced in manufacturing process of high density polyethylene was grafted with maleic anhydride (MAH). The influences of reaction parameters on the graft polymerization as well as the effect of hydrolysis of the anhydride functions were investigated. The results show that the grafting degree increased and conversion of maleic anhydride decreased with an increase in MAH monomer content. This means the highest grafting efficiency for the reaction can be met when MAH monomer content is about 15 wt%. DCP (dicumyl peroxide) and DTBP (di-tert-butyl peroxide) have been used as the initiator and the highest yield of grafting was obtained when the initiator content is about 0.5 wt%. However, It can be seen that the gel content values of this polyethylene wax grafted MAH were below 2%. It was also observed that the grafting degree increased with an increase in reaction temperature and the maximum value was reached 2 hours later. Although MAH functions grafted onto polyethylene wax were mainly in the carboxylic acid forms, some anhydride form of MAH appeared in over 5% of grafting degree. As a result of hydrolysis reaction, it was observed that the conversion of anhydride group into carboxylic acid group was reached up to 10%.

Preparation of Glycidylmethacrylate-Divinylbenzene Copolymers Containing Phosphoric Acid Groups and Adsorption Characteristics of Uranium(I) - Preparation of Glycidylmethacrylate-Divinylbenzene Copolymers Containing Phosphoric Acid Groups and Their Adsorption Characteristics of Uranium - (인산기를 함유한 Glycidylmethacrylate-Divinylbenzene 공중합체의 제조와 우라늄 흡착특성(제1보) - 인산기를 함유한 GMA-DVB 공중합체의 제조와 물성 -)

  • Huh, Kwang-Sun;Sin, Se-Geun
    • Applied Chemistry for Engineering
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    • v.9 no.5
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    • pp.680-688
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    • 1998
  • The macroreticular (MR) type glycidylmethacrylate (GMA)-divinylbenzene (DVB) copolymer (polyglycidylmethacrylate) beads (RG) were prepared by a suspension polymerization using 0~100 vol % of 2,2,4-trimethylpentane (TMP) as a diluent. Macroreticular type cation exchange resins containing phosphoric acid groups (RGP) were prepared by the reaction of GMA-DVB copolymer and poly (glycidyl methacrylate) bead (RG) with phosphoric acid in the presence of benzene. In this study, the effect of degree of crosslinking and the amount of the diluent on physical properties and adsorbability of uranium of RGP resins were investigated respectively. The chemical and physical properties of RGP resins were affected by both of the amount of the diluent and the degree of crosslinking. The effect of degree of crosslinking on the adsorbed amount of uranium for RGP resins were decreased in the order of $$RGP-10(50){\sim_=}RGP-1(50)>RGP-2(50)>RGP-5(50)>RGP-0$$. The effect of the diluent amount were as follows RGP-2(100)>RGP-2(75)>RGP-2(50)>RGP-2(30)>RGP-2(0). The crosslinking degree effect on uranium adsorbability depended on pore structure, cation exchange capability and swelling ratio. On the other hand, the effect of the diluent amount were relied on surface area and pore structure raher than cation exchange capability.

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A STUDY OF PHYSICAL PROPERTIES OF COMPOSITE RESIN POLYMERIZATION WITH ARGON LASER (아르곤 레이저에 의한 복합레진의 중합시 물성 변화에 관한 연구)

  • Kim, Deok;Min, Byung-Soon;Choi, Ho-Young;Park, Sang-Jin;Choi, Gi-Woon
    • Restorative Dentistry and Endodontics
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    • v.23 no.1
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    • pp.1-19
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    • 1998
  • After polymerizing composite resin with argon laser and visible light, four test, to be concretely, measurement of compressive strength using Instron testing machine, surface microhardness using Rockwell hardness tester, quantitative analysis of residual monomer using HPLC and analysis of degree of conversion using FTIR, were accomplished. Test groups were a sort of specimen with 3mm diameter, 4mm thickness for measuring compressive strength, two sort of specimen with 7mm diameter, 2mm and 3mm thickness for measuring surface microhardness, quantitative analysing of residual monomer after curing and measuring the degree of conversion, each were divided by six groups according to the condition of light exposure. In case of argon laser, in 1.0W and 0.5W output, the exposure time for specimen were 5 sec, 10 sec respectiyely. In case of visible light, the exposure time for specimen were 20 sec, 40 sec respectively. The test were accomplished and following results were obtained. 1. Compressive strength of composite resin was the highest in the group of 1 W output, exposing for 10 sec with argon laser, followed by the group of 0.5W, exposing for 10 sec with argon laser, the group of exposing for 40 sec with visible light. But there were statistically no significant difference between these three groups(p>0.05). 2. Surface microhardness of composite resin wasn't significantly affected by light curing conditions. 3. BIS-GMA within residual monomer was least detected in the group of exposing for 40 sec. TEGDMA was least detected in the group of 1 W output, exposing for 10 sec with argon laseboth 2mm and 3mm thickness specimen. 4. The degree of conversion of all groups in the 2mm thickness specimen were more than 50%, similar to each other but in the group of 1W, exposing 10 sec with argon laser the degree of conversion was highest in the 3mm thickness specimen. 5. Argon laser could make composite resin to has similar properties with 25% lesser exposure time than visible light.

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Effect of Milling Degree on the Physicochemical and Sensory Quality of Sogokju (도정도에 따른 소곡주의 품질 및 기호도 변이)

  • Chun, A-Reum;Kim, Dae-Jung;Yoon, Mi-Ra;Oh, Sea-Kwan;Choi, Im-Soo;Hong, Ha-Cheol;Kim, Yeon-Gyu
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.41 no.1
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    • pp.136-142
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    • 2012
  • Sogokju, a Korean glutinous rice wine and one of the oldest Korean traditional wines, is famous for its unique taste acquired from a 100-day incomplete fermentation process. This study investigated the effects of the degree of rice milling on the physicochemical and sensory characteristics of Sogokju. It evaluated the physicochemical characteristics, pasting and color properties, and structural properties of starch using four different degrees of milled rice (Oryza sativa L.) cultivar Dongjinchalbyeo. Samples of brown rice with milling yields of 92%, 84%, 76%, and 68% were produced using both abrasive and friction whiteners. This study showed that the protein, lipid, and ash content of milled rice decreased as the degree of milling increased. The lower hardness of the kernel below milling yield 92% suggested that milling may be related to the lower protein content of the kernel. The pasting curve showed a significant increase in viscosity properties as the degree of milling increased. This is due to the decrease in protein and lipid content, the increase in starch content, and the difference in amylopectin chain-length distribution. Further milling of white rice, based on 92% milling yield, had an effect on the amylopectin chain-length distribution due to the degree of polymerization (DPn) of 37~60. The long chain of amylopectin also contributed to the viscosity. The increase in the degree of milling decreased the glucose and total sugar content of Sogokju. However, it increased the total acidity of Sogokju. Moreover, the lightness of Sogokju decreased while its yellowness increased. These results indicate that the degree of milling can alter the taste and color of Sogokju. The sensory evaluation showed that the increase in the degree of milling decreased consumer preference for Sogokju. The sensory score for Sogokju was positively correlated with its brix degree, glucose content, pH, and protein content of raw rice.

SURFACE HARDNESS OF THE DENTAL COMPOSITE CURED BY LIGHT THAT PENETRATE TOOTH STRUCTURE ACCORDING TO THICKNESS OF TOOTH STRUCTURE, LIGHT INTENSITY AND CURING TIME (치질을 투과한 조사광에 의한 복합레진 중합시 치질의 두께, 광세기 및 조사 시간이 복합레진의 표면 경도에 미치는 영향)

  • Cho, Soo-Kyung;Kim, Dong-Jun;Hwang, Yun-Chan;Oh, Won-Mann;Hwang, In-Nam
    • Restorative Dentistry and Endodontics
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    • v.30 no.2
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    • pp.128-137
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    • 2005
  • In this study we measured the amount of light energy that was projected through the tooth material and analyzed the degree of polymerization by measuring the surface hardness of composites. For polymerization, Optilux 501 (Demetron, USA) with two types of light guide was used: a 12 mm diameter light guide with 840 nW/cm2 light intensity and a 7 mm diameter turbo light guide with 1100 nW/cm2. Specimens were divided into three groups according to thickness of penetrating tooth (1 mm, 2 mm, 0 mm). Each group was further divided into four subgroups according to type of light guide and curing time (20 seconds, 40 seconds). Vickers' hardness was measured by using a microhardness tester. In 0 mm and 1 mm penetrating tooth group, which were polymerized by a turbo light guide for 40 seconds, showed the highest hardness values. The specimens from 2 mm penetrating tooth group, which were polymerized for 20 seconds, demonstrated the lowest hardness regardless of the types of light guides (p < 0.05). The results of this study suggest that, when projecting tooth material over a specified thickness, the increase of polymerization will be limited even if light intensity or curing time is increased.

Physicochemical Properties and Gel-forming Properties of corn & Red bean crude Starches (옥수수와 팥 조전분의 이화학적 특성 및 겔 형성)

  • 노정해;이혜수
    • Korean journal of food and cookery science
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    • v.4 no.1
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    • pp.1-8
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    • 1988
  • The physicochemical properties and gel-forming properties of corn & red bean crude starches were investigated. The results were as follows: 1. The shape of corn crude starch granule was polygonal and the mean value of minor axis and major axis were 11.5μm and 14.9μm, respectively. In the meantime, the shape of red bean crude starch granule was oval and the mean value of minor axis and major axis were 22.3μm and 31.4μm. 2. Amylose content of corn and red bean refined starch were 16.52 and 43.61% respectively. 3. Blue value of corn and red bean crude starch were 0.099 and 0.842, respectively. 4. Amylose of corn had molecular weight of 107,000 and degree of polymerization of 660. Amylopectin had degree of branching of 6.9 per 100 glucose units and glucose units of 14.6 persegment of amylopectin. Amylose of red bean had molecular weight of 118,000 and amylopectin had degree of branching of 5.2. 5. Water binding capacities of corn and red bean starch were 238.5 and 284.8. 6. Both swelling powers of corn and red bean starch were increased rapidly from 70C to 90C. 7, Gelatinization of corn and red bean were 75.6 and 61.8C. 8. Brabender hot-paste viscosities of corn at 6% and 8% showed the similar amylogrm patterns with peak viscosity. And red bean had no peak viscosity. 9. The difference of sensory characteristics for ‘Mook’ and kidney bean & red bean starch gels was significant.

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Studies on the Syndiotactic Poly(vinyl alcohol) Polarizing Film -Iodine Desorption Behavior of High Molecular Weight Syndiotactic Poly(vinyl alcohol)/Iodine Complex Film- (신디오탁틱 폴리비닐알코올 편광필름에 관한 연구 - 고분자량 신디오탁틱 폴리비닐알코올/요오드 복합체 필름의 요오드 탈착 거동 -)

  • Lyoo, Won-Seok;Yeum, Jeong-Hyun;Choi, Jin-Hyun;Ji, Byung-Chul;Yoon, Won-Sik;Noh, Tae-Hwan;Ghim, Han-Do;Kim, Jae-Pil
    • Polymer(Korea)
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    • v.25 no.1
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    • pp.115-121
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    • 2001
  • High molecular weight syndiotactic poly(vinyl alcohol)(HMW s-PVA) with number-average degree of polymerization of 10000 and syndiotactic diad content of 61.5%/iodine complex film was prepared. Its adsorption and desorption behaviors of iodine in hot water were investigated. In comparison with atactic PVA film or low molecular weight s-PVA film, the degree of solubility of s-PVA film and the iodine desorption of HMW s-PVA/iodine film in hot water were limited to an extremely lower level. As the soaking time increased, the iodine desorption in hot water was increased. This reason might be explained by the fact that as the soaking time increased, so the iodine adsorption increased not by the stable molecular complex between PVA and iodine but by the simple physical adsorption of iodine.

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Spectroscopic Characterization and Seasonal Distribution of Aquatic Humic Substances Isolated from Han River Water (한강원수로부터 분리된 수중휴믹물질의 계절적 분포와 분광학적 특성분석)

  • Kim, Hyun-Chul;Lee, Seock-Heon;Kim, Kyung-Ju;Yu, Myong-Jin
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.5
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    • pp.540-547
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    • 2007
  • Humic substances(HS) from Han River water was physic-chemically isolated by fractionational methods to investigate the seasonal distribution and to characterize the properties compared with intrinsic humic materials. Various HS samples were analyzed by element, Fourier transform infrared(FT-IR), proton nuclear magnetic resonance(1HNMR) and fluorescence analyzers. The portion of HS from Han River water(HRHS) was 47.0% on the average, however it appeared that rainfall event brought about higher fraction of HS in Han River water by the periodic investigation. Aromaticity and humification degree of the HRHS were relatively lower than those of intrinsic humic materials originated from decomposing vegetation. FT-IR, 1HNMR and fluorescence spectroscopy showed the distinct differences between HRHS and intrinsic humic materials. Commercial humic materials could not represent structural and functional characteristics of local HS. The fluorescence spectroscopy, a relatively simple measurement, was found most useful tool to estimate humification degree for humic materials from particular sources.

Starch characteristics of foxtail millet and sorghum cultivars grown in Korea (국내 육성 조 및 수수 전분의 이화학적 특성)

  • Kim, Hyun-Joo;Woo, Koan Sik;Lee, Byong Won;Lee, Jin Young;Lee, Yu-Young;Kim, Min Young;Kim, Mihyang;Lee, Byoungkyu
    • Korean Journal of Food Science and Technology
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    • v.52 no.3
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    • pp.220-225
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    • 2020
  • In this study, we investigated the starch characteristics of foxtail millet (FM) and sorghum (SG) cultivars grown in Korea. The amylose contents were 29.42 and 6.42% in the Daname and Samdachal FM cultivars, and 9.09 and 11.11% in the Nampungchal and Sodamchal SG cultivars, respectively. The amylopectin polymerization analysis showed that the highest degree of polymerization (DP) was in the range of DP13-24 for all samples, at approximately 60%. The resistant starch content was very low (<0.10%) among the FM and SG cultivars. The starch gelatinization analysis showed low setback values in the Samdachal and Nampungchal cultivars. The gelatinization enthalpy, calculated based on an endothermic reaction, did not differ significantly between the SG cultivars but was significantly higher in the Samdachal FM cultivars than in the Daname FM cultivars. The results of this study might be used as basic data for the development of FM and SG products.