纳米粒子改性环氧树脂玻璃化转变温度的研究

采用示差扫描量热分析(DSC)研究了纳米A l2O3粒子改性的环氧树脂基体玻璃化转变温度与纳米粒子含量之间的关系以及纳米粒子含量对改性体系固化剂用量的影响。结果表明,随着纳米粒子含量的提高,改性树脂的玻璃化转变温度逐渐下降,由纯树脂的224℃下降到182.5℃(纳米粒子用量30%,固化剂添加量70%)。并且纳米粒子的加入会影响树脂基体的固化反应。达到玻璃化转变温度峰值时的固化剂用量并非按照改性体系中环氧树脂含量等当量比加入,而是与纳米粒子含量有关,纳米粒子含量越高,达到玻璃化转变温度峰值时固化剂用量越少。     

改性氧化碳纳米管对环氧树脂基复合材料热膨胀系数的影响

采用氧化多壁碳纳米管(O-MWCNTs)和四氧化三铁改性氧化多壁碳纳米管(Fe_3O_4/O-MWCNTs)对环氧树脂(EP)进行修饰,研究了改性O-MWCNTs对EP基体热膨胀系数(CTE)的影响。结果表明:改性O-MWCNTs由于其表面的官能团可与EP基体形成共价键,从而增强了二者之间的界面作用力。相对于纯EP,O-MWCNTs和Fe_3O_4/O-MWCNTs改性EP的玻璃化转变温度(T_g)分别升高了4.77和6.15℃;两种改性EP在T_g之下的CTE值分别降低了32.7%和41.8%,而T_g之上的CTE值均高于纯EP。     

核壳聚合物增韧环氧树脂的研究进展

核壳聚合物(CSP)用来增韧环氧树脂的最大优点,在于提高韧性的同时而不降低材料的玻璃化转变温度(Tg)和加工性能。综述了核壳聚合物增韧环氧树脂的特点,核壳聚合物的制备方法、微观结构及形态,以及增韧环氧树脂及其复合材料的性能及影响因素。     

纳米核壳橡胶的合成及其对EP的增韧改性

以丁苯橡胶(SBR)为核,以聚甲基丙烯酸甲酯为壳,合成了3种不同核壳比的纳米核壳橡胶(CSP)粒子,并研究了核壳比对粒子尺寸形态及分散性的影响。结果表明,纳米CSP的接枝率随核壳比降低而增大,而粒子尺寸几乎没有变化,即制备的纳米CSP粒子尺寸依赖于所选取的SBR胶乳粒子尺寸。从而确定了核壳比为70/30的CSP–1为环氧树脂(EP)的增韧剂。根据EP/CSP–1共混体系的扫描电子显微镜照片,确定采用三辊研磨式分散方法制备该共混体系。以EP/液体端羧基丁腈橡胶(CTBN)共混体系为对比,探讨了不同含量的CSP–1对EP黏度、韧性、模量及耐热性的影响。结果表明,CSP–1的质量分数低于10%时,体系黏度增加范围小于10 Pa·s,对于体系的加工和固化性能无明显影响。当增韧剂质量分数为5%时,EP/CSP–1体系的临界应力强度因子和临界应变能释放率分别比EP/CTBN体系提高了20.45%和42.95%,而弯曲弹性模量下降率仅为EP/CTBN体系下降率的一半,与CTBN的加入导致EP玻璃化转变温度(Tg)下降的现象相比,加入CSP–1的EP Tg几乎不变。以上表明CSP–1作为EP的增韧剂在韧性、模量和耐热性上比CTBN更有优势。     

低膨胀系数环氧胶粘剂的制备与性能研究

文章设计选用低膨胀环氧树脂和固化剂为胶粘剂主体成分,研究了CTBN、核壳粒子增韧剂、超细钨酸锆填料对粘接性和膨胀性的影响,分析测定了低膨胀胶粘剂的粘度特性、物理性能、粘接性能和热膨胀特性。结果表明, CTBN能显著提高胶粘剂韧性,但热膨胀系数(CTE)显著升高,而核壳粒子增韧剂在提高剥离韧性同时, CTE无显著升高。超细钨酸锆填料能大幅降低环氧胶粘剂的CTE。制备的低膨胀环氧胶粘剂固化后剪切强度17.4MPa,玻璃化转变温度以下CTE在12.1ppm/℃,具有良好的耐温度循环和湿热老化性能。     

核壳粒子改性中温固化环氧基体树脂的研究

采用核壳粒子增韧改性制备了一种可中温固化的环氧预浸料基体树脂,研究了增韧改性环氧树脂微观形貌、固化反应活性、耐热性、力学性能和黏温特性。结果表明,核壳粒子在树脂中均匀分散,固化树脂断裂面为银纹增多的韧性断裂。增韧后环氧树脂的力学性能有所提高,加入7%核壳粒子改性树脂的冲击强度达26k J/m2,改性基体树脂玻璃化转变温度为165℃。通过对树脂DSC曲线和黏温曲线的研究考察了基体树脂的使用工艺性,确定中温固化环氧基体树脂的固化工艺为:100℃/1h+130℃/2h。     

用液态含羧基丙烯酸酯低聚物改性环氧树脂

采用溶液聚合法合成了以丙烯酸丁酯、丙烯腈为主链结构的液态含羧基丙烯酸酯低聚物,用其对环氧树脂进行增韧改性,讨论了丙烯腈、丙烯酸以及丙烯酸酯低聚物质量分数对改性环氧树脂力学性能的影响,并研究了改性环氧树脂的微观形态和动态力学性能。结果表明,丙烯酸酯低聚物质量分数为5％时,丙烯酸丁酯／丙烯腈／丙烯酸（质量比）为75／20／5的改性环氧树脂的拉伸强度比纯环氧树脂提高4．3％;丙烯酸酯低聚物质量分数为10％时,该改性环氧树脂的冲击强度比纯环氧树脂提高近4倍,同时体系的耐热性能保持不变;环氧树脂改性体系呈两相结构,丙烯酸酯低聚物质量分数达到30％时,对环氧树脂的增韧效果变差;随着丙烯酸酯低聚物质量分数的增加,改性环氧树脂的玻璃化转变温度先升高后降低,其质量分数不超过10％时,改性环氧树脂的玻璃化转变温度高于纯环氧树脂。     

环氧树脂改性核壳乳胶粒子的制备

采用预乳化-半连续种子乳液聚合工艺制备了环氧树脂改性聚丙烯酸丁酯/(聚甲基丙烯酸甲酯-衣康酸)(PBA/P(MMA-ITA-DGEBA))核壳乳胶粒子。采用激光粒度仪、傅立叶变换红外光谱(FTIR)、差示扫描量热仪(DSC)、透射电子显微镜(TEM)等方法对核壳乳胶粒子进行了表征,实验结果表明:PBA/P(MMA-ITA-DGEBA)乳胶粒子确为核壳结构,双酚A型环氧树脂已经被成功接枝到核壳乳胶粒子上,由于ITA、DGEBA链段的存在,导致壳层PMMA玻璃化转变温度的(Tg)升高。     

有机硅核壳聚合物增韧环氧树脂胶黏剂

有机硅核壳聚合物(CSP)是一种以柔软而有弹性的交联有机硅(PDMS)为核、以聚甲基丙烯酸甲酯(PMMA)为壳的核壳聚合物,采用这种核壳聚合物增韧环氧基体树脂,采用FTIR、SEM、TGA和DSC对其化学结构、断面形貌和热性能进行了表征。结果表明,CSP添加量仅为10%即获得了最好的增韧效果,冲击强度达到了17.308 kJ/m~2,比纯环氧树脂的冲击强度提高了95.3%,拉伸强度、剪切强度在CSP添加量为30%时分别达到了峰值4.58 MPa和28.44 MPa,相比于纯环氧树脂分别提高了275%和120%。     

PBA/PS核壳聚合物的制备及其与PS共混

采用种子乳液聚合方法制备了丙烯酸丁酯/苯乙烯核壳结构聚合物,研究了不同核壳单体质量比对乳液聚合过程的影响.结果表明,单体的总转化率超过98%;假设乳胶粒为球形生长时,乳胶粒理论粒径与实测值基本一致,说明该聚合体系没有明显的二次成核过程.随着核壳单体质量比的增加,低温区(聚丙烯酸丁酯)的玻璃化转变温度变化不大,而高温区(聚苯乙烯)的玻璃化转变温度呈下降趋势,这说明该核壳结构界面存在明显的过渡层.将该乳液聚合物与聚苯乙烯共混,随着核壳单体质量比的增加,共混物的冲击强度呈先增加后降低的趋势,说明该核壳聚合物对聚苯乙烯的增韧存在最佳条件.     

有机硅改性环氧树脂的合成与性能

热熔法制备了系列聚甲基苯基硅氧烷(PMPS)改性环氧树脂,通过环氧值、红外光谱(IR)和凝胶色谱(GPC)分析表明,有机硅接枝到了环氧树脂上,且环氧基保持不变。探讨了改性方法、有机硅含量对改性树脂固化体系的微观形态、韧性及耐热性的影响。实验表明,当m(E-20)∶m(DC-3074)=7∶3时,化学改性树脂固化体系的韧性和耐热性能明显提高,玻璃化转变温度(Tg)为88.33℃,质量损失50%时的热分解温度(Td)为487.80℃,分别比物理改性环氧树脂提高了52.63℃和36.75℃,同时此改性树脂固化物还具有优良的涂膜性能。     

环氧树脂增韧改性技术研究进展和新方法及其机理

简单介绍了环氧树脂技术的研究进展和近期的主要应用,并概述了环氧树脂的改性技术.主要介绍了增韧改性的一些新方法,包括热塑性树脂增韧、互穿网络增韧、热致性液晶增韧、原位聚合增韧、核壳结构聚合物增韧等,主要介绍了用橡胶弹性体、热塑性树脂、刚性粒子、核壳型结构聚合物来增韧环氧树脂,以及环氧树脂绝缘性、耐湿热性和阻燃性等的改进方法,并对其中的增韧机理作了总结分析.最后本文综述了环氧树脂增韧改性技术发展及其未来展望.     

改性环氧树脂及其在石质文物保护中的研究进展

综述了国内外环氧树脂改性方法的研究现状及其在作为石质文物保护材料中的研究进展。其中环氧树脂的改性方法包括:橡胶弹性体改性、热塑性树脂改性、核壳聚合物改性、热致液晶聚合物改性、嵌段聚合物改性、齐聚倍半硅氧烷结构改性、互穿聚合物网络改性、超支化聚合物改性以及纳米粒子改性等,并比较讨论了各种方法的优缺点。同时论述了改性后的环氧树脂,特别是用纳米材料改性的环氧树脂在石质文物中的研究现状及应用前景。     

核壳聚合物增韧环氧树脂的研究及进展

核壳聚合物(CSP)用来增韧环氧树脂的最大优点,即在提高韧性的同时而不降低材料的Tg和加工性能。综述了核壳聚合物增韧环氧树脂的特点,核壳聚合物的制备方法、微观结构及形态,以及增韧环氧树脂及其复合材料的性能及影响因素。树枝形聚合物作为一种结构特殊的聚合物,也越来越得到广泛的研究和应用。并对环氧树脂的增韧机理进行了阐述,即空穴化-塑性形变。文中还对核壳聚合物及树枝形聚合物增韧环氧树脂进行了展望。     

Core-shell particles designed for toughening the epoxy resins. II. Core-shell-particle-toughened epoxy resins

The diglycidyl ether of bisphenol A–m-phenylene diamine (DGEBA–MPDA) epoxy resin was toughened with various sizes and amounts of reactive core-shell particles (CSP) with butyl acrylate (BA) as a core and methyl methacrylate (MMA) copolymerized with various concentration of glycidyl methacrylate (GMA) as a shell. Ethylene glycol dimethacrylate (EGDMA) was used to crosslink either core or shell. Among the variables of incorporated CSP indicated above, the optimal design was to obtain the maximum plastic flow of epoxy matrix surrounding the cavitated CSP during the fracture test. It could be achieved by maximizing the content of GMA in a shell-crosslinked CSP, the particle size, and the content of CSP in the epoxy resin without causing the large-scale coagulations. The incorporation of reactive CSP could also accelerate the curing reaction of epoxy resins. Besides, it was able to increase the glass transition temperature of epoxy resins if the particle size ≤0.25 μm and the dispersion was globally uniform. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2313–2322, 1998     

含芳醚芴二胺/环氧树脂固化反应动力学及性能研究

以9,9-双[4-4-氨基苯氧基苯基]芴(BAOFL)作为固化剂,采用非等温DSC技术,研究了BAOFL/环氧树脂(E-51、TDE-85和芴基环氧树脂)体系的固化反应动力学,利用动态热机械分析仪(DMA)和热重分析仪(TGA)测试了固化树脂的力学性能和热稳定性。结果表明,固化反应活化能与环氧树脂和固化剂的结构密切相关,芳醚的引入提高了氨基与环氧基的反应性,固化树脂呈现出优良的热性能和力学性能,其玻璃化转变温度(T)达到206~248℃,贮能模量为2.54~2.94 GPa,初始热分解温度312~375℃,700℃g时的残炭率达到15.2%~31.7%。()     

Study on Properties of Low Dieletric loss Resin Matrix

Summary One new high performance modified BMI resin matrix with enhanced processing characteristics, made from 4,4-bismaleimidodiphenyl methane (BDM) and allyl phenyl compounds, allyl epoxy resins and epoxy acrylate resins, were developed. Solubility, differential scanning calorimetry (DSC), gel time, and Fourier transform infrared (FTIR) spectroscopy were used to detect the structure and processing characteristics of the modified BMI resin and neat BDM. Results show that the new modified BMI resin systems have enhanced processability compared with neat BDM, especially improved solubility and faster thermal polymerization rate. In addition, the new cured systems have more than two times improved impact strength without a great decrease in excellent dielectric properties or thermal and hot–wet resistance of neat BDM resin.     

Thermo-mechanical behaviors of epoxy resins reinforced with nano-Al2O3 particles

This study examined the thermo-mechanical behavior of epoxy resins/nano-Al₂O₃ composites including the curing behavior, thermal stability, dynamic mechanical properties and thermal mechanical properties. The DSC curve peak temperature of the composites was decreased by the addition of nano-Al₂O₃. The thermal stability of the composites was similar to that of the neat epoxy resins. Dynamic mechanical analysis (DMA) indicated the glass transition temperature of the composites to be approximately 11 °C higher than that of the neat epoxy resins. The coefficient of thermal expansion (CTE) of the composites decreased with increasing nano-Al₂O₃ content.     

The studies of physical properties of dimeric fatty acid-modified thiodiphenyl epoxy resins

A thermally stable thiodiphenyl epoxy resin was modified with a dimeric fatty acid at an epoxy resin:fatty acid molar ratio of 4:1. The thermal and mechanical properties of the modified epoxy resin were studied by preparing an epoxy composition with an amine curing agent and a catalyst, followed by curing at 170 °C to produce a neat plastic epoxy resin. The tensile and impact strengths of the resin indicated improved flexibility and toughness compared to other epoxy resins. Enhanced toughness was confirmed by the increased lap shear strength in single lap joints prepared with steel substrates attached by the resin.     

The influence of the core–shell structured meta-aramid/epoxy nanofiber mats on interfacial bonding strength and the mechanical properties of epoxy adhesives at cryogenic environment

The adhesives for adhesively bonded joints at cryogenic environment should be enhanced by reinforcement with low coefficient of thermal expansion (CTE) and high fracture toughness because the materials become quite brittle at cryogenic temperature. Aramid fibers are noted for their low CTE and have been used to control the CTE of thermosetting resins. However, aramid composites exhibit poor adhesion between the fibers and the resin because the aramid fibers are chemically inert and contain insufficient functional groups. In this work, core–shell structured meta-aramid/epoxy nanofiber mats were fabricated by electrospinning with polymer blending method to improve the interfacial bonding between the adhesive and the fibers under cryogenic temperature. The CTE of the epoxy adhesives reinforced with modified nanofiber mats was measured, and the effect on the adhesion strength was investigated at single lap joints at cryogenic temperature. The fracture toughness of the adhesive joints was measured using a double cantilever beam (DCB) test.