Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates
Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates
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DOI：
10.1016/j.tca.2015.08.008
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发表时间：
2015-09-20
影响因子：
3.5
通讯作者：
Ziegmann, G.
中科院分区：
文献类型：
--
作者：
Duemichen, E.;Javdanitehran, M.;Ziegmann, G.
近红外光谱（NIR）被证明非常适合于分析环氧树脂体系的固化程度。与动态扫描量热法（DSC）相比，NIR光谱能够通过分析结构变化直接确定环氧转化率，而DSC是通过反应释放的热量间接确定环氧转化率。因此，一种新的可加热近红外单元配备了一个集成的热电偶，这使得真实的样品温度可以在环氧树脂固化过程中进行控制和监测。在不同的加热速率下的动态扫描用于动力学建模，以定义动力学参数并预测真实的固化过程。动力学模型和它们的参数进行了验证与等温和一个更复杂的多步固化方案。两种基于DGEBA的市售环氧体系与酸酐和胺硬化剂一起使用。将NIR结果与DSC数据进行了比较。用NIR和DSC动态扫描拟合的模型预测的模拟转化率与等温固化验证试验中测得的转化率吻合良好。由于近红外在测量固化反应过程中的可靠性，它可以被认为是一种通用的测量系统，用于汽车、航空航天和风能领域的组件生产现场监测。(C)2015 Elsevier B.V.版权所有。
Near-infrared spectroscopy (NIR) turned out to be well suited for analyzing the degree of cure for epoxy systems. In contrast to dynamic scanning calorimetry (DSC), where the released heat of reaction determines the degree of epoxy conversion indirectly, NIR spectroscopy is able to determine the conversion directly by analyzing structural changes. Therefore, a new heatable NIR cell was equipped with an integrated thermocouple, which enables the real sample temperature to be controlled and monitored in situ during epoxy curing. Dynamic scans at different heating rates were used for kinetic modelling, to define kinetic parameters and to predict real curing processes. The kinetic models and their parameters were validated with an isothermal and a more complex multi-step curing scenario. Two available commercial epoxy systems based on DGEBA were used with an anhydride and with an amine hardener. NIR results were compared with DSC data. The simulated conversion predicted with a model fitted on the basis of NIR and DSC dynamic scans showed good agreement with the conversion measured in the isothermal curing validation test. Due to the proven reliability of NIR in measuring the reaction progress of curing, it can be considered a versatile measurement system for in situ monitoring of component production in the automotive, aerospace and wind energy sectors. (C) 2015 Elsevier B.V. All rights reserved.