• 제목/요약/키워드: cure kinetics

검색결과 92건 처리시간 0.032초

중합조건에 따른 dual cured resin cement의 열분석적 연구 (THERMAL ANALYSIS OF THE DUAL CURED RESIN CEMENTS ACCORDING TO CURING CONDITION)

  • 이인복;정관희;엄정문
    • Restorative Dentistry and Endodontics
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    • 제24권2호
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    • pp.265-285
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    • 1999
  • The purposes of this investigation were to observe the reaction kinetics of five commercial dual cured resin cements (Bistite, Dual, Scotchbond, Duolink and Duo) when cured under varying thicknesses of porcelain inlays by chemical or light activation and to evaluate the effect of the porcelain disc on the rate of polymerization of dual cured resin cement during light exposure by using thermal analysis. Thermogravimetric analysis(TGA) was used to evaluate the weight change as a function of temperature during a thermal program from $25{\sim}800^{\circ}C$ at rate of $10^{\circ}C$/min and to measure inorganic filler weight %. Differential scanning calorimetry(DSC) was used to evaluate the heat of cure(${\Delta}H$), maximum rate of heat output and peak heat flow time in dual cured resin cement systems when the polymerization reaction occured by chemical cure only or by light exposure through 0mm, 1mm, 2mm and 4mm thickness of porcelain discs. In 4mm thickness of porcelain disc, the exposure time was varied from 40s to 60s to investigate the effect of the exposure time on polymerization reaction. To investigate the effect on the setting of dual cured resin cements of absorption of polymerizing light by porcelain materials used as inlays and onlays, the change of the intensity of the light attenuated by 1mm, 2mm and 4mm thickness of porcelain discs was measured using curing radiometer. The results were as follows 1. The heat of cure of resin cements was 34~60J/gm and significant differences were observed between brands (P<0.001). Inverse relationship was present between the heat of reaction and filler weight % the heat of cure decreased with increasing filler content (R=-0.967). The heat of reaction by light cure was greater than by chemical cure in Bistite, Scotchbond and Duolink(P<0.05), but there was no statistically significant difference in Dual and Duo(P>0.05). 2. The polymerization rate of chemical cure and light cure of five commercially available dual cured resin cements was found to vary greatly with brand. Setting time based on peak heat flow time was shortest in Duo during chemical cure, and shortest in Dual during light cure. Cure speed by light exposure was 5~20 times faster than by chemical cure in dual cured resin cements. The dual cured resin cements differed markedly in the ratio of light and chemical activated catalysts. 3. The peak heat flow time increased by 1.51, 1.87, and 3.24 times as light cure was done through 1mm, 2mm and 4mm thick porcelain discs. Exposure times recommended by the manufacturers were insufficient to compensate for the attenuation of light by the 4mm thick porcelain disc. 4. A strong inverse relationship was observed between peak heat flow and peak time in chemical cure(R=0.951), and a strong positive correlations hip was observed between peak heat flow and the heat of cure in light cure(R=0.928). There was no correlationship present between filler weight % or heat of cure and peak time. 5. The thermal decomposition of resin cements occured primarily between $300^{\circ}C$ and $480^{\circ}C$ with maximum decomposition rates at $335^{\circ}C$ and $440^{\circ}C$.

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천연 제올라이트/에폭시 복합재료의 경화반응 속도론 (Cure Kinetics of Natural Zeolite/Epoxy Composites)

  • 이재영;천인숙;심미자;김상욱
    • 공업화학
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    • 제7권2호
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    • pp.387-392
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    • 1996
  • 천연 제올라이트/에폭시 수지 복합재료의 경화반응 속도론을 연구하기 위해 DSC 분석법 중 승온적 방법을 이용하였다. 천연 제올라이트의 함량이 증가함에 따라 반응 시작온도와 발열피크의 온도가 낮아졌다. Diglycidyl ether of bisphenol A(DGEBA)/4,4'-methylene dianiline(MDA)/malononitrile(MN, 10phr)에 제올라이트를 20phr 충전한 경우에는 하나의 발열피크가 나타나며, 30phr인 경우에는 shoulder가 나타났다. 40phr의 제올라이트가 충전된 경우에는 발열피크가 두 개로 분리되며, 첫번째 발열피크의 활성화에너지, $Ea_1$은 12.30 kJ/mol이고, 두번째 발열피크의 활성화에너지, $Ea_2$는 12.70 kJ/mol이었다.

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석조문화재 보존.복원에 적용될 에폭시 수지의 경화 시 반응열 제어 및 안정성 향상 연구 (Tuning Exothermic Curing Reaction of Hydrogenated Bisphenol A Epoxy Resins for Stone Conservation)

  • 최용석;박유진;강용수;원종옥;김정진;김사덕
    • 보존과학회지
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    • 제28권2호
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    • pp.131-139
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    • 2012
  • 석조문화재의 보존 복원 과정에 적용되는 에폭시 수지에 경화제의 혼합을 통하여 경화 시 발열 반응을 제어할 수 있는 접착 시스템을 연구하였다. 사용된 에폭시 주제는 hydrogenated bisphenol A (HBA), 경화제로는 속경화형 경화제 FH와 poly(propyleneglycol)bis(2-aminopropylether) (SH)를 사용하였으며, 무기 첨가물은 탈크를 사용하였다. 에폭시 수지와 경화제의 혼합비에 따라 경화 시 온도를 측정하고, differental scanning calorimeter (DSC)를 이용하여 경화동력학을 확인하였으며, 기계적 특성을 파악하기 위해 무기 첨가물의 함량에 따른 인장강도, 전단강도를 측정하였다. 연구 결과, 에폭시 수지의 경화제 혼합을 통하여 경화 시 반응열 상승폭 제어 및 경화 거동 제어의 가능성을 확인하였으며, 무기 첨가물 첨가를 통해 적절한 강도 조절이 가능하여 석조문화재에 적용 가능한 새로운 접착 시스템을 개발하였다.

LED 패키징용 실리콘의 경화공정 모델링 (A cure process modeling of LED encapsulant silicone)

  • 송민재;김흥규;강정진;김권희
    • Design & Manufacturing
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    • 제6권1호
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    • pp.84-89
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    • 2012
  • Silicone is recently used for LED chip encapsulment due to its good thermal stability and optical transmittance. In order to predict residual stress which causes optical briefringence and mechanical warpage of silicone, finite element analysis was conducted for both curing and cooling process during silicone molding. For analysis of curing process, a cure kinetics model was derived based on the differential scanning calorimetry(DSC) test and applied to the material properties for finite element analysis. Finite element simulation result showed that the curing as well as the cooling process should be designed carefully so as to reduce the residual stress although the cooling process plays the bigger role than curing process in determining the final residual stress state. In addition, birefringence experiment was carried out in order to observe residual stress distribution. Experimental results showed that cooling-induced birefringence was larger than curing-induced birefringence.

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MN/HQ가 첨가된 에폭시 수지계의 경화반응 연구 (Cure Reaction of Epoxy Resin System with MN/HQ)

  • 천인숙;심미자;김상욱
    • 공업화학
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    • 제5권6호
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    • pp.967-974
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    • 1994
  • DGEBA(Diglycidyl ether of bisphenol A)/MDA(4, 4' -methylene dianiline)/MN(Malononitrile)/HQ(Hydroquinone)계의 경화 반응속도론을 differential scanning calorimetry(DSC)의 승온적 방법(dynamic runs)에 의해 Barrrett method와 Integral method로 연구하였다. 활성화 에너지, pre-exponential factor와 같은 kinetic parameter들이 구하여 졌으며 반응 차수는 본계가 n차 반응 속도식에 적용된다는 가정하에 추정되었다. MN(Malononitrile)은 본 반응의 사슬 연장제로, HQ(Hydroquinone)은 반응 가속제 또는 촉매로 도입되었다.

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에폭시 수지의 경화 거동에 미치는 반응성 희석제의 영향 (Effects of Reactive Diluents on the Curing Behavior of Epoxy Resin)

  • 김완영;이대수;김형순;김정기
    • 공업화학
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    • 제5권6호
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    • pp.1030-1035
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    • 1994
  • 에폭시 수지의 성형 가공성을 조절하기 위해 반응성 희석제를 사용했을 때의 경화특성 및 경화 후 유리 전이온도의 변화를 조사하였다. 반응성 희석제로 사용한 Butyl gilcidyl ether(BGE) 및 Phenyl glycidyl ether(PGE)함량의 증가에 따라 경화에 따른 발열량과 경화 후 유리 전이온도는 낮아지는 특성이 관찰되었다. 에폭시 수지는 BGE를 사용한 경우 PGE를 사용한 경우보다 더 낮은 유리 전이온도를 보였으며, 희석제의 첨가에 따른 유리 전이온도 변화는 가교점 사이의 분자량 증가 때문으로 해석하였다. 에폭시 수지의 경화 거동을 자촉매 반응에 대한 속도론식으로 해석한 결과 속도상수 $k_1$, $k_2$는 희석제의 양에 따라 감소하였다.

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Azomethine 기를 가지는 신소재 액정 에폭시 (LCE)와 지방족 아민의 경화반응 (Curing Reaction of Noble Liquid Crystalline Epoxy (LCE) with Azomethine/Aliphatic Amine)

  • 김상욱
    • 한국재료학회지
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    • 제11권9호
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    • pp.786-791
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    • 2001
  • $\alpha$,$\omega$-Bis(4-glycidyloxybenzylidene-4-aminophenyl)methane (BGBAM) was synthesized from the initial materials, 4-hydroxylbenzaldehyde (HBA), 4,4'-methylenedianiline (MDA) and epichlorohydrin. The DSC trace for BGBAM shows two endotherms associated with the liquid crystalline phase transition around $104.2^{\circ}C$ and the isotropic transition around $171.2^{\circ}C$, and it also has a broad exotherm in the range of $178~300^{\circ}C$ due to the anionic homopolymerization of BGBAM. DSC curve for the curing of BGBAM with hexamethylene diamine (HMD) shows an endothermic peak around $93^{\circ}C$ attributed to the melting of BGBAM. It also has three exothermic peaks around $128.4^{\circ}C$ and $180.2^{\circ}C$ associated with the epoxide-amine reaction and weak peak in the range of $200~263^{\circ}C$ related to the anionic homopolymerization between the unreacted epoxide groups. The activation energy values of cure reaction by Kissinger method are 66.5, 67.3 and 90.6 kJ/mol for $T_{pl},\; T_{p2}\; and \;T_{p3},\; respectively$. The kinetic parameters by isoconverional method are similar value to those from Kissinger method.

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Effect of Cross-Linking Characteristic on the Physical Properties and Storage Stability of Acrylic Rubber

  • Seong-Guk Bae;Min-Jun Gim;Woong Kim;Min-Keun Oh;Ju-Ho Yun;Jung-Soo Kim
    • Elastomers and Composites
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    • 제58권3호
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    • pp.136-141
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    • 2023
  • Polyacrylic rubber (ACM) is well known for its excellent heat resistance and chemical stability. Additionally, its performance can be readily manipulated by modifying its functional groups, rendering it highly attractive to various industries. However, extreme climate changes have necessitated an expansion of the operating temperature range and lifespan of ACM products. This requires the optimization of both the compounding process and functional-group design. Hence, we investigated the relationship between the cross-linking system and mechanical properties of an ACM with a carboxylic cure site. The crosslink density is determined by chemical kinetics according to the structure of additives, such as diamine crosslinkers and guanidine accelerators. This interaction enables the manipulation of the scotch time and mechanical properties of the compound. This fundamental study on the correlation analysis between cross-linking systems, physical properties, and storage stability can provide a foundation for material research aimed at satisfying the increasingly demanding service conditions of rubber products.

초고압 절연 스페이서의 자동가압 겔화 성형 공정을 위한 경화 보압의 최적화 (Optimization of Curing Pressure for Automatic Pressure Gelation Molding Process of Ultra High Voltage Insulating Spacers )

  • 이찬용;조한구;이재형
    • 한국전기전자재료학회논문지
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    • 제37권1호
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    • pp.56-62
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    • 2024
  • By introducing curing kinetics and chemo-rheology for the epoxy resin formulation for ultra-high voltage gas insulated switchgear (GIS) Insulating Spacers, a study was conducted to simulate the curing behavior, flow and warpage analysis for optimization of the molding process in automatic pressure gelation. The curing rate equation and chemo-rheology equation were set as fixed values for various factors and other physical property values, and the APG molding process conditions were entered into the Moldflow software to perform optimization numerical simulations of the three-phase insulating spacer. Changes in curing shrinkage according to pack pressure were observed under the optimized process conditions. As a result, it was confirmed that the residence time in the solid state was shortened due to the lowest curing reaction when the curing holding pressure was 3 bar, and the occurrence of deformation due to internal residual stress was minimized.

2관능성 에폭시/생분해성 폴리부틸렌 숙시네이트 블렌드의 유변학적 특성 및 경화거동에 관한 연구 (Studies on Rheological Properties and Cure Behaviors of Difunctional Epoxy/Biodegradable Poly(butylene succinate) Blends)

  • 박수진;김승학;이재락;민병각
    • Composites Research
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    • 제15권6호
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    • pp.8-15
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    • 2002
  • 본 실험에서는 2관능성 에폭시 수지(2EP)와 생분해성 poly(butylene succinate)(PBS) 블렌드의 유변학적 특성, 경화거동, 열안정성 그리고 기계적 특성을 살펴보았다. 유변학적 특성은 레오미터를 이용하여 등온 조건 하에서 검토하였고, 겔화시간과 경화 온도를 이용한 Arrhenius 방정식을 적용하여 가교 활성화 에너지($\textrm{E}_c$)를 구하였다. $\textrm{E}_c$는 2EP에 대한 PBS의 비율이 10 wt%로 증가함에 따라 증가하였다. DSC 측정 결과, 경화 활성화 에너지($\textrm{E}_a$)는 $\textrm{E}_c$와 유사만 경향을 나타내었는데 이는 2EP와 PBS 사이의 분자상호작용이 증가하였기 때문으로 사료된다. 그리고 열안정성과 관련하이 분해 활성화에너지($\textrm{E}_t$)는 Horowitz-Metzger식을 이용한 적분법을 사용하여 구하였는데 PBS 10 wt%에서 증가하였다. 그리고 20 wt% PBS일 때 가장 높은 임계응력세기 인자를 보이는데, 이는 2EP/PBS 블렌드 시스템의 파괴인성이 증가하였기 때문으로 사료된다.