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摘要
通过差示扫描量热法(等温DSC和非等温DSC)研究了白水泥、膨润土、粉煤灰等无机填料对环氧树脂-聚酰胺体系固化动力学的影响;利用流变仪对体系的触变性能进行了测试。研究发现,环氧树脂-聚酰胺体系的固化反应级数在2～3左右,该反应具有自催化反应的特征,在90～100℃温度条件下,固化反应全段可用Kamal模型描述;而在反应温度较低时(50～80℃),固化前期可以用Kamal模型描述,后期反应由化学控制向扩散控制转变,只能用扩散控制的反应机理模型描述。在100份环氧树脂中加入5份稀释剂和50份无机填料,当填料为白水泥、粉煤灰以及粒径325目的膨润土时,在80℃条件下固化反应全段仍然可以用Kamal模型描述。当填料为粒径400目的膨润土时,体系的触变性显著增强,固化反应初始可以用Kamal模型描述,后期转为扩散控制,所以体系的流动性变差是导致固化反应动力学由化学控制转为扩散控制的主要因素。
Abstract
The effect of inorganic fillers,white cement,bentonite,flay ash,on curing reaction kinetics of bisphenol-A epoxy resin and low molecular weight polyamide was investigated under iso-thermal curing condition using Differential Scanning Calorimeter (DSC) technique.Meanwhile,the thixotropic properties of them were measured using a rheometer.The relation between curing reaction kinetics and thixotropic properties were discussed.It was found that,the reaction order of bisphenol-A epoxy resin and low molecular weight polyamide system under different temperatures fallen in between 2 and 3,indicating that the reaction can be characterized by autocatalytic mechanism proposed by Kamal model equation.Under 90～100℃,the whole curing reaction process can be described by Kamal model equation.Under 50～80℃,unlike the initial process of the curing reaction,which can be well described by Kamal model equation,the later part of the curing reaction turned from autocatalytic mechanism into diffusion controlled mechanism.After added 5 portions of diluent and 5 portions of fillers per 100 portions of epoxy resin,when cured at 80℃,Kamal model gave a good description for the systems of white cement,flay ash and bentonite of 325 mesh was up to the onset of vitrification.The curing reaction process of system filled with bentonite of 400 mesh,which had a remarkable larger thixotropic loop was hardly described by the Kamal model at the later stage,indicating that the shortage of mobility was the key reason for the reaction turning Kamal model to diffusion controlled mechanism.
关键词
环氧树脂
/
聚酰胺
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无机填料
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等温固化
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固化动力学
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触变行为
Key words
epoxy
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polyamide
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inorganic filler
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iso-thermal curing
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curing reaction kinetics
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thixotropic property
填料对环氧树脂固化动力学及触变性能的影响[J].
化工新型材料, 2019, 47(12): 177-182 DOI:
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基金资助
国家自然科学基金面上项目(51578557)
