环氧灌封材料的制备、结构与性能研究

【作者】 哈恩华；

【导师】 寇开昌；

【作者基本信息】 西北工业大学 ， 材料学， 2004， 硕士

【摘要】 随着航空、电子等事业的发展，灌封器件的高性能化对灌封材料提出了越来越高的要求。探索制备环氧灌封材料的新方法，寻求提高其使用性能的有效途径是该领域研究的重要课题。本文利用硅微粉、纳米SiO₂和蒙脱土通过不同环氧体系制备方法的研究，对环氧灌封材料的微观结构、性能及相关影响因素进行了较为系统的分析和讨论。 首先通过共混技术，分别用普通硅微粉和活性硅微粉制备出填充改性环氧材料，实验结果表明，填充改性后，耐热性和电性能明显提高，线膨胀系数显著降低。其中活性硅微粉比普通硅微粉在力学性能尤其是冲击强度、浸水后的电性能和耐吸水性方面效果更好。 采用原位分散聚合法制备了环氧树脂／纳米SiO₂材料，并通过透射电镜（TEM）、扫描电镜（SEM）、差示扫描量热法（DSC）等对材料的结构与性能进行了分析和讨论。结果表明，所制备的环氧树脂／纳米SiO₂材料具有纳米材料的结构特征，对于提高环氧树脂的力学性能、热学性能及其电性能等都有作用，其中线膨胀系数明显降低，冲击强度和弯曲强度在SiO₂含量3％附近出现最大值，分别提高112％和109％。认为材料制备时所采用的硅烷偶联剂，使降低了纳米SiO₂的表面能，有利于纳米SiO₂粒子在环氧树脂中的分散并易被大分子链浸润，对材料纳米结构的形成和性能的改善具有重要作用。同时，因材料中纳米SiO₂用量少，粘度变化很小，对工艺性能没有多大影响。 在环氧树脂／蒙脱土纳米复合材料的制备中，用十六烷基三甲基氯化铵通过阳离子交换的方法对蒙脱土进行了有机化处理，使蒙脱土由亲水性变成亲油性，其层间距也由原来的1.2nm扩大到2.2nm。用X射线衍射仪、透射电镜等研究了有机蒙脱土在环氧体系中的插层、剥离行为，并测试了所制材料的性能。结果表明，环氧树脂与有机蒙脱土的相容性好；混合条件和固化剂是影响有机蒙脱土在环氧树脂中剥离的两个重要因素，在一定的混合条件下并选用合适的固化剂可以使蒙脱土在环氧树脂中完全剥离；剥离型环氧树脂／蒙脱土纳米复合材料的力学性能、电性能、热性能以及吸水性能与纯环氧树脂固化物相比均有不同程度的提高和改善。 在各种不同制备方法研究的基础上，选用不同的改性体系制备出环氧灌封材料，并对其性能作了评价。结果表明，活性硅微粉对环氧灌封材料的热变形温度和电学性能提高较为显著，尤其在浸水后，电学性能降低幅度很小， 西北工业大学硕士学位论文但活性硅微粉用量较大，材料的工艺性能明显降低;纳米5102对环氧灌封材料具有显著的增强和增韧作用，冲击强度、弯曲强度由原来的13.95 kJ/mZ和64.95 MPa分别提高到27.64kjzm2和136.68MPa。蒙脱土使环氧灌封材料的冲击强度和弯曲强度由纯环氧树脂的14.24kJ/mZ和91.%MPa分别提高到18.24kJ/m2和109.84 MPa;耐热性得到了很大提高，当有机蒙脱土含量为5%时纳米复合材料玻璃化温度比纯环氧固化物的高出13.2’C;热变性温度最大提高16℃;线膨胀系数当蒙脱土含量为1%时，环氧灌封材料的线膨胀系数比未加时降低了44%，吸水率明显下降。更多还原

【Abstract】 Encapsulating materials of epoxy resin are modified with HGH, nano-SiO2 and organophilic montmorillonite, in the present investigation, the microstructue, some properties and influence factors about nano-SiO2 and organophilic montmorillonite modified Encapsulatig materials have been systematically studied using X-ray diffraction, electron microscopy and differential thermal analysis measurement techniques.The modified epoxy resin materials with HG and HGH have first been preformed. Properties test results show that the electricity properties and heat distortion temperature are improved by addition of HG or HGH in the epoxy resin materials, and the materials containing HG or HGH have lower linear thermal expansion coefficiency compared with neat epoxy resin. When the modified materials were in water for 24 hours, the mechanical properties and electricity properties of the materials with HGH are better than that of the materials with HG.Epoxy resin/nano- SiO2 composite materials were obtained from in situ polymerization, and then the microstructure and properties of the materials are investigated by transmission electron microscopy, scanning electron microscopy and differential scanning calorimetry,etc.Results indicated that the microstructure of the modified materials shew the structure of nanometer materials, and the mechanical properties, heat distortion temperature and electricity properties and of the materials were all improved by addition of nano- SiO2 .After the nano-SiO2 was pretreated with organic silicon coupling agent (H2N-CH2CH2CH2-Si(OC2H5)n), the nano-SiO2 particles were dispersed in epoxy resin matrix homogeneously. When the content of nano-SiO2 is3wt%, the mechanical properties of the nanocomposites were the best, impact strength is 98% higher than that of epoxy resin, flexural strength is 112% higher than when nano-SiO2 is Owt%. The differential scanning calorimetry analyses show that the addition of nano-SiO2 increases the glass transition temperature.Organophilic montmorillonite was obtained by cation exchange on montmorillonite surface, which was modified from hydrophilic to hydrophobic and led to the increase in the basal distance between silicate layers of about 1nm. The intercalation and exfoliation behavior of organophilic montmorillonite in DGEBA-montmorillonite system have been investigated by X-ray diffraction and transmission electron microscopy and the properties of nanocomposites were tested. The results show that the affinity between the organophilic montmorillonite and diglycidylether of bisphenol A was very well. Curing agents and mixing conditions were two important factors that effected on exfoliation behavior of organophilicmontmorillonite in diglycidylether of bisphenol A matrix. The organophilic montmorillonite was exfoliated completely and there were no d001 diffraction peaks with methyltetrahydrophthalic anhydride as curing agent and benzyldimethylanine as catalyst. Properties test results show that mechmical properties, electricity properties ,heat distortion temperature of the exfoliated nanocomposites were all improved by addition of the montmorillonite, and the nanocomposites had lower linear thermal expansion coefficiency and water absorption compared with neat epoxy resin.Based on the over research ,three different kinds of encapsulating materials of epoxy resin are performed. Test results show that that the breakcown voltage and heat distortion temperature the encapsulating materials of epoxy resin with HGH are famously improved, but the the addition of HGH, the viscosities of the epoxy resin-HGH system is higher compared with that of the others and the encapsulating process is effected. Nano- SiO2 improves the mechanical properties of encapsulating materials of epoxy resin,impact strength reaches 27.64kJ/m2 from 13.95 kJ/m2 ,flexural strength reaches 136.68MPa from64.95 MPa. by addition of the montmorillonite, glass transition temperature and heat distortion temperature of the encapsulating materials are 13.2℃ and 16℃ higher than that of epoxy re更多还原