• 제목, 요약, 키워드: cure kinetics

검색결과 93건 처리시간 0.043초

일정온도 상승률 열분석법을 이용한 수지 경화 모델 개발 (A New Cure Kinetic Model Using Dynamic Differential Scanning Calorimetry)

  • 엄문광;황병선
    • 연구논문집
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    • pp.151-162
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    • 1999
  • In general, manufacturing processes of thermosetting composites consist of mold filling and resin cure. The important parameters used in modeling and designing mold filling are the permeability of the fibrous preform and the viscosity of the resin. To consolidate a composite, resin cure or chemical reaction plays an essential role. Cure kinetics. Therefore, is necessary to quantify the extent of chemical reaction or degree of cure. It is also important to predict resin viscosity which can change due to chemical reaction during mold filling. There exists a heat transfer between the mold and the composite during mold filling and resin cure. Cure kinetics is also used to predict a temperature profile inside composite. In this study, a new scheme which can determine cure kinetics from dynamic temperature scaning was proposed. The method was applied to epoxy resin system and was verified by comparing measurements and predictions.

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Photostabilization and Cure Kinetics of UV-Curable Optical Resins Containing Photostabilizers

  • Cho, Jung-Dae;Kim, Sung-Hwa;Chang, In-Cheol;Kim, Kwon-Seok;Hong, Jin-Who
    • Macromolecular research
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    • v.15 no.6
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    • pp.560-564
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    • 2007
  • The photostabilization and cure kinetics of UV-curable, optical resins containing various formulations of photostabilizers were investigated to determine the system with the highest cure conversion and durability. Photo-DSC analysis revealed that increasing the concentration of a UV absorber (UVA) decreased both the crosslink density and the cure rate due to competition for the incident photons between the photoinitiator and the UVA, whereas including a hindered amine light stabilizer (HALS) hardly affected either the cure conversion or the cure rate due to its very low absorption of 365 nm. This result was confirmed by FTIR-ATR spectroscopy and UV-visible spectroscopy analyses. QUV ageing experiments showed that the cure conversion and durability were the highest for the UVA/HALS formulation at a ratio of 1 : 2, which is due to their synergistic action.

Investigation of Cure Kinetics and Storage Stability of the o-Cresol Novolac Epoxy Nanocomposites with Pre-intercalated Phenolic Hardeners

  • Hwang, Tae-Yong;Lee, Jae-Wook;Lee, Sang-Min;Nam, Gi-Joon
    • Macromolecular research
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    • v.17 no.2
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    • pp.121-127
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    • 2009
  • The cure kinetics of the epoxy-layered, silicate nanocomposites were studied by differential scanning calorimetry under isothermal and dynamic conditions. The materials used in this study were o-cresol novolac epoxy resin and phenol novolac hardener, with organically modified layered silicates. Various kinetic parameters, including the reaction order, activation energy, and kinetic rate constants, were investigated, and the storage stability of the epoxy-layered silicate nanocomposites was measured. To synthesize the epoxy-layered silicate nanocomposites, the phenolic hardener underwent pre-intercalation by layered silicate. From the cure kinetics analyses, the organically modified layered silicate decreased the activation energy during cure reaction in the epoxy/phenolic hardener system. In addition, the storage stability of the nanocomposite with the pre-intercalated phenolic hardener was significantly increased compared to that of the nanocomposite with direct mixing of epoxy, phenolic hardener, and layered silicate. This was due to the protective effect of the reaction between onium ions and epoxide groups.

열경화성 수지의 온도에 따른 경화도와 비열(Cp) 변화 (The Change of Degree of Cure and Specific Heat Capacity According to Temperature of Thermoset Resin)

  • 신동우;황성순;이호성;김진원;최원종
    • Composites Research
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    • v.28 no.3
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    • pp.99-103
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    • 2015
  • 본 논문에서는 복합재료 제조공정 중 온도에 따른 경화 반응을 이해하고 열분석을 수행하였으며, 이 결과를 바탕으로 온도에 따른 수지의 경화도 및 비열의 변화를 수식화하였다. 온도에 따른 경화도와 비열은 DSC와 MDSC (Modulated DSC)를 활용하여 측정하였다. DSC와 MDSC 분석은 Isothermal과 Dynamic 조건으로 수행하여 Cure Kinetics, 유리전이온도 및 비열을 측정하고, 회기 분석 방법을 이용하여 물성거동을 수학적으로 모델링하였다.

승온 반응속도식을 이용한 LED용 실리콘 렌즈의 경화 및 열전달해석 (Cure and Heat Transfer Analysis in LED Silicone Lens using a Dynamic Cure Kinetics Method)

  • 송민재;김권희;홍석관;박정연;이정원;윤길상
    • 소성가공
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    • v.24 no.2
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    • pp.101-106
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    • 2015
  • Recently, silicone is being used for LED chip lens due to its good thermal stability and optical transmittance. In order to predict residual stresses, which cause optical birefringence and mechanical warpage of silicone, a finite element analysis was conducted for the curing of silicone during molding. For the analysis of the curing process, a dynamic cure kinetics model was derived based on the results of a differential scanning calorimetry (DSC) testing and applied to the material properties for finite element analysis. Finite element simulation results showed that a step cure cycle reduced abrupt reaction heat and showed a decrease in the residual stresses.

에폭시/폴리옥시프로필렌 디아민계의 경화 반응속도 및 동역학 특성 분석 (Cure Kinetics and Dynamic Mechanical Properties of an Epoxy/Polyoxypropylene Diamine System)

  • 황광춘;이종근
    • 폴리머
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    • v.35 no.3
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    • pp.196-202
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    • 2011
  • 비즈페놀 A 에폭시 수지와 폴리옥시프로필렌 디아민 경화제계의 경화 반응속도를 시차주사열량계을 이용하여 승온 및 등온 경화조건에서 조사하였다. 승온실험에서는 Ozawa와 Kissinger법을 이용하여 다양한 가열속도에서 얻어진 발열피크의 이동으로부터 활성화 에너지를 구하였다. 또한 등온실험에서 얻어진 데이터는 자촉매 효과를 고려한 Kamal의 속도모델로 분석하였으며, 그 결과 경화반응 초기의 속도우세 구간에서 실험데이터와 잘 맞았다. 반응 후기의 확산우세 구간에서는 확산효과를 적용하여 경화의 전체과정을 기술하였다. 또한 동역학분석을 이용하여 경화 후 저장 탄성률과 가교점간의 평균분자량을 측정하였다.

Isoconversional Cure Kinetics of Modified Urea-Formaldehyde Resins with Additives

  • Park, Byung-Dae
    • Current Research on Agriculture and Life Sciences
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    • v.30 no.1
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    • pp.41-50
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    • 2012
  • As a part of abating formaldehyde emission of urea-formaldehyde resin, this study was conducted to investigate the rmalcure kinetics of both neat and modified urea-formaldehyde resins using differential scanning calorimetry. Neat urea-formaldehyde resins with three different formaldehyde/urea mol ratios (1.4, 1.2 and 1.0) were modified by adding three different additives (sodium bisulfite, sodium hydrosulfite and acrylamide) at two different levels (1 and 3wt%). An isoconversional method at four different heating rates was employed to characterize thermal cure kinetics of these urea-formaldehyde resins to obtain activation energy ($E{\alpha}$) dependent on the degree of conversion (${\alpha}$). The $E{\alpha}$ values of neat urea-formaldehyde resins (formaldehyde/urea = 1.4 and 1.2) consistently changed as the ${\alpha}$ increased. Neat and modified urea-formaldehyde resins of these two F/U mol ratios did show a decrease of the $E{\alpha}$ at the final stage of the conversion while the $E{\alpha}$ of neat urea-formaldehyde resin (formaldehyde/urea = 1.0) increased as the ${\alpha}$ increased, indicating the presence of incomplete cure. However, the change of the $E{\alpha}$ values of all urea-formaldehyde resins was consistent to that of the Ea values. The isoconversional method indicated that thermal cure kinetics of neat and modified urea-formaldehyde resins showed a strong dependence on the resin viscosity as well as diffusion control reaction at the final stage of the conversion.

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휘발물질이 존재하는 열경화성수지 복합재료의 Pultrusion 공정 해석 (Analysis of the Pultrusion Process of Thermosetting Composites Containing Volatiles)

  • 김대환;이우일;김병선
    • 대한기계학회논문집
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    • v.19 no.2
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    • pp.527-536
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    • 1995
  • Analysis of pultrusion process for the thermosetting composites containing volatiles was performed. Degree of cure, amount of volatile evolved and pulling force were calculated for the processing variables such as die temperature and pulling speed. Cure kinetics was modeled from the data obtained by DSC(Differential Scanning Calorimeter). The volatile evolution kinetics was modeled from the data by DSC as well as TGA(Thermo Gravimetric Analyzer). The cure kinetics and volatile evolution kinetics models were incorporated into the energy equation. The resulting governing equation was solved using finite element method. Pulling force was calculated through the analysis of pressure developed inside the pultrusion die. Experiments were performed and the data were compared with the calculated results. Good agreements were observed.

비대칭 고리형 지방족 아민 경화제를 이용한 DGEBF 계열 에폭시의 경화 거동 (Cure Behavior of a DGEBF Epoxy using Asymmetric Cycloaliphatic Amine Curing Agent)

  • 김홍경
    • Korean Chemical Engineering Research
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    • v.46 no.1
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    • pp.200-204
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    • 2008
  • 비대칭성 고리형 지방족 아민 경화제를 이용한 diglycidyl ether of bisphenol F(DGEBF) 계열의 에폭시의 경화 반응을 등온 및 동적 경화 실험을 통하여 분석하였다. 등온 부분경화 실험 및 동적 경화반응을 통하여 아민 경화제의 비대칭성으로 인해 경화 반응이 저온부 및 고온부분의 두 가지 반응으로 구성되어 있다는 것을 확인하였고, 따라서 경화도가 0.6 이상인 영역에서는 등온경화반응 모델식을 이용하여 실험값을 예측하기는 어렵다는 것을 확인하였다. 승온 속도를 여러 가지로 변화시키며 동적 경화반응을 분석하여 저온부 및 고온부 각각의 반응에 대한 활성화에너지 및 속도상수를 알아보았고, 경화 초기에는 저온부의 반응이 주가 되는 것을 확인하였다.

전하전이착체형 잠재성 촉매를 사용한 반도체 성형용 자소성 에폭시 수지 시스템의 경화 반응속도 연구 (Cure Kinetics of Self-Extinguishing Epoxy Resin Systems with Charge Transfer Complex Type Latent Catalyst for Semiconductor Encapsulation)

  • 김환건
    • 반도체디스플레이기술학회지
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    • v.13 no.4
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    • pp.27-32
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    • 2014
  • The cure properties of self-extinguishing epoxy resin systems with different charge transfer type latent catalysts were investigated, which are composed of YX4000H as a biphenyl epoxy resin, MEH-7800SS as a hardener, and charge transfer type latent catalysts. We designed and used five kinds of charge transfer type latent catalyst and compared to epoxy resin systems with Triphenylphosphine-Benzoquinone(TPP-BQ) as reference system. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The epoxy resin systems with Triphenylphosphine-Quinhydrone(TPP-QH), Triphenylphosphine-Benzanthrone(TPP-BT) and Triphenylphosphine-Anthrone(TPP-AT) as a charge transfer type latent catalyst showed a cure conversion rate of equal or higher rate than those with TPP-BQ. These systems with TPP-QH and Triphenylphosphine-Tetracyanoethylene(TPP-TCE) showed a critical cure reaction conversion of equal or higher conversion than those with TPP-BQ. The increases of cure conversion rates could be explained by the decrease of the activation energy of these epoxy resin systems. It can be considered that the increases of critical cure reaction conversion would be dependent on the crystallinity of the biphenyl epoxy resin systems.