• Title, Summary, Keyword: cure kinetics

Search Result 93, Processing Time 0.055 seconds

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

  • Eom, Mun-Gwang;Hwang, Byeong-Seon;Isaac M. Daniel
    • 연구논문집
    • /
    • /
    • pp.151-162
    • /
    • 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.

  • PDF

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
    • /
    • v.15 no.6
    • /
    • pp.560-564
    • /
    • 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
    • /
    • v.17 no.2
    • /
    • pp.121-127
    • /
    • 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.

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

  • Shin, Dong-Woo;Hwang, Seong-Soon;Lee, Ho-Sung;Kim, Jin-Won;Choi, Won-Jong
    • Composites Research
    • /
    • v.28 no.3
    • /
    • pp.99-103
    • /
    • 2015
  • This paper presents the cure kinetics studies on the cure reaction of thermosetting resin. Above all, change in degree of cure and specific heat capacity according to temperature are observed using DSC and MDSC. The results are analyzed by cure kinetics and specific heat capacity model. Glass transition temperature was also measured to apply to the specific heat capacity model. Model parameters were gained from the modeling result. As a result, behavior of specific heat capacity can be calculated mathematically.

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

  • Song, M.J.;Kim, K.H.;Hong, S.K.;Park, J.Y.;Lee, J.W.;Yoon, G. S.
    • Transactions of Materials Processing
    • /
    • v.24 no.2
    • /
    • pp.101-106
    • /
    • 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.

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

  • Huang, Guang-Chun;Lee, Jong-Keun
    • Polymer Korea
    • /
    • v.35 no.3
    • /
    • pp.196-202
    • /
    • 2011
  • The cure kinetics of a bisphenol A epoxy resin and polyoxypropylene diamine curing agent system are investigated in both dynamic and isothermal conditions by differential scanning calorimetry (DSC). In dynamic experiments, the shift of exothermic peaks obtained at different heating rates is used to obtain activation energy of overall cure reaction based on the methods of Ozawa and Kissinger. Isothermal DSC data at different temperatures are fitted to an autocatalytic Kamal kinetic model. The kinetic model is in a good agreement with the experimental data in the initial stage of cure. A diffusion effect is incorporated to describe the later stage of cure, predicting the cure kinetics over the whole range of curing process. Also, dynamic mechanical analysis is performed to evaluate the storage modulus and average molecular weight between crosslinkages.

Isoconversional Cure Kinetics of Modified Urea-Formaldehyde Resins with Additives

  • Park, Byung-Dae
    • Current Research on Agriculture and Life Sciences
    • /
    • v.30 no.1
    • /
    • pp.41-50
    • /
    • 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.

  • PDF

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

  • 김대환;이우일;김병선
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.19 no.2
    • /
    • pp.527-536
    • /
    • 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.

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

  • Kim, Hongkyeong
    • Korean Chemical Engineering Research
    • /
    • v.46 no.1
    • /
    • pp.200-204
    • /
    • 2008
  • The curing kinetics of diglycidyl ether of bisphenol F (DGEBF) with an asymmetric cycloaliphatic amine curing agent were examined by thermal analysis in both isothermal and dynamic curing conditions. From the residual curing of the samples partially cured in isothermal condition and from the dynamic curing with various heating rates, it was found that there exist two kinds of reactions such as at low temperature and at high temperature regions. It was thus also found that the cure parameters obtained from the isothermal curing kinetic model hardly estimate experimental results for a degree of cure larger than 0.6. The activation energies and frequency factors of these two kinds of reactions were obtained from the dynamic curing experiments with various heating rates. From the curing analysis, it was verified that the total cure kinetics for low degrees of cure is dominated by the cure reaction in the low temperature region.

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

  • Kim, Whan Gun
    • Journal of the Semiconductor & Display Technology
    • /
    • v.13 no.4
    • /
    • pp.27-32
    • /
    • 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.