• 공업화학
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• 제16권5호
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• pp.672-676
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• 2005

치아수복용 고분자 복합체(polymeric dental restorative composite, PDRC)의 전치부와 구치부에의 응용 가능성을 높이고자 PDRC를 구성하는 실리카 충진재를 다양한 온도에서 열처리시켜 siloxane 기로 연결된 구조의 개질된 실리카를 제조하고 이를 PDRC 제조에 사용하였다. 제조된 PDRC의 중합 특성을 중합전환률, 중합깊이, 그리고 체적 중합수축률 등을 분석하여 고찰하였다. 실험 결과, 사용된 실리카의 열처리 온도가 높아짐에 따라 제조된 PDRC의 중합깊이는 감소하였고 체적 중합수축률과 중합전환률 값은 실리카 입자의 평균크기 감소에 따른 PDRC 내 resin matrix의 상대적 양의 증가로 인해 일정하게 증가함을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.234-236
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• 1993

Dielectric properties of low viscous silicone oils have been investigated as a function of frequency and The increase of polymerization degree was attributed to presence of Si-O-Si bonds and their increased dissociation factor. The application of the Clausius-Mosotti equation on the low viscous silicone oils, it has been previously assumed that the oils were dilute solutions of polar molecules. In the silicone oil the Si-o and O-Si bonds give dipole polarization. Simple relations have been found which dipole moment and activation energy as a function of number of Si atoms in the low viscous silicone oils.

• 한국식품영양과학회지
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• 제26권3호
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• pp.436-442
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• 1997

Corn starch was extruded under relatively low shear, high moisture, and low temperature. Puffing of corn starch dough was induced by injecting $CO_2$gas in the range from 0MPa to 0.09MPa. Piece density and compressive modulus for puffed corn starch were decreased by increasing the injection pressure to 0.07MPa, and increased above 0.07MPa. the microstructure of corn starch puffed with $CO_2$gas showed thick cell size, compared with those puffed with steam. RVA paste viscosity curves of corn starch puffed with $CO_2$had different patterns from those puffed with steam, probably resulted from partial gelatinization of starch. Water absorption and solubility were not significantly changed by $CO_2$injection pressure, but the average degree of polymerization was reduced by higher $CO_2$injection. The water absorption, water solubility, and the average degree of polymerization for corn starch puffed with $CO_2$were significantly lower than those puffed with steam.

• 대한가정학회지
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• 제19권2호
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• pp.213-221
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• 1981

This theiss deals with the effects of addition of silicone oil to the polymerization and oxidation of frying oil in the practical deep fat frying process. The measurement of frying oil stability was carried out under various silicone oil content and compared with controlled frying process. In controlled frying process A.V., C.O.V., TBA, and contents of petroleumether insoluble fatty acids were increased as time was increased. It means thermal oxidized polymerization and hydrolysis of frying oil was occurred. When silicone oil was added to frying oil, it's thermal stability was better than that of the controlled oil and the degree of thermal stability was changed according to the contents of silicone oil. We obtained the highest degree of thermal stability when silicone oil was added 1ppm.

• Macromolecular Research
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• 제17권1호
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• pp.26-30
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• 2009

To modify and strengthen the properties of PHEMA hydrogel, composite hydrogels containing varying amounts of a Pluronic (PEO-PPO-PEO) component were synthesized by bulk polymerization of HEMA in the presence of Pluronic dimethacrylate under mild photo initiating conditions. The effects of the Pluronic component on gel properties were investigated by measuring the degree of swelling with its temperature responsive behavior, the mechanical properties, and the morphology of the composite hydrogels. With increased Pluronic content, the modified PHEMA hydrogels exhibited an increase in the degree of swelling, and the swelling showed an enhanced thermo-responsive behavior that was completely reversible. In addition, improved mechanical strength and the development of a microporous gel morphology were observed in hydrogels containing Pluronic.

• 대한화학회지
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• 제13권4호
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• pp.379-386
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• 1969

Polyethylene maleate (PEM) and epoxy resin cinnamate (BEC) were prepared to investigate their photosensitivity. Various samples coated on glass plate were exposed to light under various conditions and steeped in the same solvent as used for coating, and then the yield of residual film (W/$W_0$) was calculated. The yield (W/$W_0$), which was closely related to the sensitivity of the film, was affected by the degree of polymerization of the film, light source, sensitizers land their concentration. In polymer homologs, the sensitivity depended upon degree of polymerization. Most effective sensitizers for PEM and BEC among those used here were benzanthrone and 2,6-dichloro-4-nitroaniline.

• 한국염색가공학회지
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• 제15권3호
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• pp.154-160
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• 2003

Polypropylene nonwoven fabrics were grafted with acrylic acid by a preirradiation method by using electron beam accelerator. The effect of irradiation dose, storage time, concentration of acrylic acid, reaction temperature, reaction time and Mohr's salt concentration on the degree of grafting were investigated in detail. The grafted Polypropylene nonwoven fabrics were characterized using IR spectroscopy and SEM. The results showed that the degree of grafting increased with increasing absorbed dose and the Mohr's salt in the acrylic acid solution promoted grafting efficiency.

• Journal of the Korean Wood Science and Technology
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• 제25권4호
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• pp.45-50
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• 1997

This research was studied for dissolving pulp preparation as the raw material of viscose rayon from woody biomass by solvolysis pretreatment. In the change of pulp characteristic after solvolysis pretreatment, the following results were obtained. In the case of solvolysis pretreatment, we have obtained pulp that high purity cellulose, and degree of polymerization was inclined to decrease less than 440 on the phosphoric acid as catalyst. Comparing phosphoric acid and formic acid as catalyst in the solvolysis pretreatment, using on formic acid catalyst is superior to phosphoric acid catalyst for making dissolving pulp.

• 펄프종이기술
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• 제29권3호
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• pp.51-59
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• 1997

Dissolving pulp is a low yield(30∼35%) bleached chemical pulp that has a high cellulose content (95% or higher) suitable for use in cellulose derivatives such as rayon, cellulose acetate. This research was studied for dissolving pulp preparation as the raw material of viscose rayon from commertial pulps. (TMP, CP, DIP) In the change of pulp(cellulose) characteristics after sodium hypochlorite and solvolysis treatment. the following results were obtained In the case of sodium hypochlorite pretreatment, we have obtained pulp that high purity cellulose, but degree of polymerization was inclined to decrease less than 170∼240. Comparing sodium hypochlorite pretreatment and solvolysis pretreatment, solvolysis pretreatment is superior to sodium hypochlorite process for making dissolving pulp. We think that the low degree of polymerization of cellulose because of increasing degradation of cellulose during delignification treatment.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.565-566
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• 2003

The clinical performance of light polymerized composite resins is greatly influenced by the quality of the light curing unit used. Commonly used halogen light curing units(LCUs) have some specific drawbacks such as decreasing light output with time. To overcome this, the blue LED LCUs are newly developed and introduced. The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue LED LCUs compared with conventional halogen LCUs.(omitted)