Highly anisotropic thermal conductivity of mesogenic epoxy resin film through orientation control

To develop insulating materials with a high thermally conductive anisotropy, planarly aligned mesogenic epoxy (ME) resin film was fabricated by uniaxial coating on a hydrophobic polyethylene terephthalate substrate. Grazing incidence small-angle X-ray scattering (GISAXS) and transmission SAXS measurements exhibited that the films spontaneously formed uniaxially aligned monodomain-like smectic structures by curing on the hydrophobic substrate. Then, an in- and out-of-plane thermal conductivity of 10 and 0.048 W m⁻¹ K⁻¹ and outstanding thermal conductivity anisotropy of 208 have been confirmed, respectively. The ME resin films with high thermal conductivity can be applied as insulating materials for multiple-layer electrical and electronic devices.     

Synthesis of a novel biphenyl epoxy resin and its hybrid composite with high thermal conductivity

A novel biphenyl epoxy monomer of p-methyl phenylhydroquinone epoxy resin (p-MEP) was synthesized and characterized. We researched its potential in the area of thermal conduction application and prepared a series of hybrid composites based on it with different mass ratios of sphere Al₂O₃ filler. From the good mobility and low viscosity of p-MEP, it allowed mixing with more Al₂O₃ fillers. The hybrid epoxy resins owned the advantages of traditional epoxy resins as well as quite considerable thermal conductivity. Therefore, the hybrid composite at the maximum mass fraction of 70% possess the highest thermal conductivity of 5.6 W mK⁻¹, which is 5.6 times higher than that of pristine p-MEP (0.1 W mK⁻¹). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47078.     

环氧树脂/玻璃布/BN导热复合材料的制备与性能研究

采用高温模压成型法制备环氧树脂(EP)/玻璃布/氮化硼(BN)导热复合材料。探讨了BN用量和偶联剂处理对复合材料力学性能、导热性能和介电性能等影响。结果表明:当w(BN)=15%时,复合材料的冲击强度较高;导热性能随着BN用量的增加而增大;当w(BN)=25%时,改性复合材料的热导率为0.901 2 W/(m.K),此时复合材料仍保持较低的介电常数和介电损耗。当BN用量相同时,偶联剂表面处理可有效改善复合材料的力学性能和导热性能。     

高导热苯乙烯丙烯酸树脂复合材料制备及导热性能

苯乙烯丙烯酸树脂为墨粉主要组分,其导热性能提升可显著提高墨粉导热性能,进而延长打印、复印机使用寿命。通过在苯乙烯丙烯酸树脂中添加碳纳米管、石墨烯高导热单一或复合填料,在苯乙烯丙烯酸树脂构建连通导热网络以提高其导热性能。当苯乙烯丙烯酸树脂中添加0.75wt%多壁碳纳米管时,其导热系数可提高至0.1644 W/(m?K),增幅为31.31%;添加1.0wt%羧基改性多壁碳纳米管时,苯乙烯丙烯酸树脂导热系数可提高至0.1751 W/(m?K),增幅为39.86%;在苯乙烯丙烯酸树脂添加多壁羧基改性碳纳米管和石墨烯混合填料时,苯乙烯丙烯酸树脂导热系数可提升至0.2093 W/(m?K),增幅达到67.17%。表明碳纳米管和石墨烯混合填料可在苯乙烯丙烯酸树脂中形成有效的导热网络,从而显著提高苯乙烯丙烯酸树脂导热性能。     

高温固化环氧树脂胶粘剂的研究

以酚醛环氧树脂(F-51)、不同种类的固化剂和填料等为主要原料,配制不同的EP(环氧树脂)双组分复合材料修补用胶粘剂。采用单因素试验法优选出制备EP胶粘剂的较佳工艺条件。结果表明:当m(F-51)∶m(固化剂PA651)=100∶55、m(气相白炭黑)∶m(高岭土)=15∶80时,制成的EP双组分胶粘剂可在较高温度(室温/1 d→170℃/1 h)条件下固化,其剪切强度为13.8 MPa、压缩强度为85.1 MPa和压缩模量为5.7 GPa,并且其凝胶时间较长、流动性控制性较好、耐介质浸泡性和操作方便性俱佳,完全满足复合材料修补用胶粘剂的使用要求。     

高断裂伸长率环氧树脂体系的研究

在环氧树脂(EP)体系中引入大分子聚醚胺固化剂(D-2000、T-5000)或柔韧性EP(DER-732、EPI-CLON830、133L),并研究了改性剂的种类、用量对EP体系拉伸性能和粘接性能的影响。研究结果表明,大分子聚醚胺和柔韧性EP的加入明显提高了EP体系的断裂伸长率;添加大分子聚醚胺的最佳体系为E-51/D-400/D-2000体系,当w(D-2000)=30份时,断裂伸长率为53.6%、拉伸强度为17.8MPa;添加柔韧性EP的最佳体系为E-51/DER-732/D-400体系,当w(DER-732)=25份时,断裂伸长率可达130%、拉伸强度为13.0MPa;高断裂伸长率EP体系粘接铝材的拉伸剪切强度为25MPa左右。     

天然鳞片石墨/环氧树脂复合材料的制备及导热性能研究

以天然鳞片石墨为导热填料,E44型环氧树脂为基体,采用超声分散法制备天然鳞片石墨/环氧树脂复合导热材料.系统考察了天然鳞片石墨用量、石墨粒度和炭黑添加量等因素对复合材料导热性能的影响.结果表明:随着天然鳞片石墨用量增加,复合材料的导热系数增大,抗压强度先增加后减小;复合材料的导热系数随天然石墨粒径的增大而增大,抗压强度先减小后增加;在石墨/环氧树脂复合导热材料中添加不同用量的炭黑时,随着炭黑添加量的增加,复合材料的抗压强度增大,导热系数先增大后减小.制备天然鳞片石墨/环氧树脂复合导热材料的最佳配方为天然鳞片石墨用量45％,粒径≤270 μm,炭黑用量2％.     

A graphite nanoplatelet/epoxy composite with high dielectric constant and high thermal conductivity

A simple strategy for the preparation of composites with high dielectric constant and thermal conductivity was developed through a typical interface design. Graphite nanoplatelets (GNPs) with a thickness of 20–50 nm are fabricated and homogeneously dispersed in the epoxy matrix. A high dielectric constant of more than 230 and a high thermal conductivity of 0.54 W/mK (a 157% increase over that of pure epoxy) could be obtained for the composites with a lower filler content of 1.892 vol.%. The dielectric constant still remains at more than 100 even in the frequency range of 10⁵–10⁶ Hz. When loaded at 2.703 vol.%, GNP/epoxy composites have a dielectric constant higher than 140 in the frequency range of 10²–10⁴ Hz and a high thermal conductivity of 0.72 W/mK, which is a 240% increase over that of pure epoxy. The high dielectric constant and low loss tangent are observed in the composite with the GNPs content of 0.949 vol.% around 10⁴ Hz. It is believed that high aspect ratio of GNPs and oxygen functional groups on their basal planes are critical issues of the constitution of a special interface region between the GNPs and epoxy matrix and the high performance of the composites.     

Liquid crystalline epoxy resin cured by mesogenic hardening compounds

Summary A new type of liquid crystalline epoxy resin functionalized with mesogenic hardening agent was obtained by reacting stoichiometrically 4,4-bis (2,3-epoxypropoxy)-3,35,5-tetramethyl biphenyl (EPTB) (diepoxide monomer) with 4,4-bis (-carboxy decanoxy) azoxybenzene (CDA10) (mesogenic hardening monomer) at 145°C for 10 min, using tri-n-butylamine as a catalyst. Mesomorphic phase transition behavior for EPTB-CDA10 prepolymer obtained was studied as function of curing time at 140°C by use of DSC and polarized microscopy. When the curing time is shorter than a gelling time (60 min), EPTB-CDA10 showed a liquid crystalline state reminiscent of smectic phase, while that reminiscent of nematic phase, when the curing time is longer than the gelling time. This work indicates that the new type of epoxy resin cured by mesogenic hardening compound can have a liquid crystal state.     

液晶环氧树脂改性普通环氧树脂的研究

合成了一种液晶环氧树脂,并使之与普通环氧树脂共混固化,共混固化物的力学性能和热稳定性比普通环氧树脂固化物有明显的提高。     

炭黑/环氧树脂复合材料导电行为的研究

分别采用不同的混合分散方法制备炭黑/环氧树脂(CB/EP)复合材料(CB牌号为F101、XE2,EP牌号为E-54、E-51和E-44),研究了制备工艺、CB用量和CB结构等对复合材料导电性能的影响。结果表明:不同方法制得的复合材料体积电阻率的大小依次为机械混炼法离心混合法超声分散法;CB/EP复合材料的导电性能随CB用量增加而显著提高,并且F101/E-54、XE2/E-54复合材料体系均表现出明显的导电渗流行为;CB结构对复合材料的导电性能影响较大,F101/E-54、XE2/E-54复合材料体系的导电渗流阈值分别为3.85%、0.47%。     

Fabrication of graphene/epoxy resin composites with much enhanced thermal conductivity via ball milling technique

Ball milling is selected to prepare composites of graphene nanoplatelets (GNPs) and epoxy. Much enhanced thermal conductivity was recorded with higher GNP loading, which varied between 5 and 25 wt %. A maximum thermal conductivity of 2.67 W/m·K was found. The prepared composites were characterized by scanning electron microscopy, transmission electron microscopy, and Raman. It was found that KNG180, a commercially available kind of natural graphite, with a thickness of 30 ～ 80 nm were mainly exfoliated into GNPs (<10 layers) with high quality, which were in turn uniformly dispersed in the composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40565.     

增韧导热环氧树脂/氮化硼复合材料的制备与表征

采用种子乳液聚合方法制备了聚（丙烯酸正丁酯/甲基丙烯酸甲酯-co-甲基丙烯酸缩水甘油酯）核壳增韧剂（PBMG）,并用湿法球磨与超声辅助相结合的方法对六方氮化硼（h-BN）进行改性,制备的改性氮化硼（MBN）可提高环氧树脂（EP）的热导率。最后采用机械共混方法制备了环氧树脂/增韧剂/改性氮化硼（EP/PBMG/MBN）复合材料。通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）、X射线衍射（XRD）、动态激光光散射（DLS）、热导率和力学性能等测试对核壳增韧剂的粒子形成、改性氮化硼和复合材料进行了表征。结果发现：最终制备的聚丙烯酸酯乳胶粒子呈现明显的核壳结构,且粒度分布很窄。当聚丙烯酸酯增韧剂添加量为5%、改性氮化硼为8.99%时,环氧树脂/增韧剂/改性氮化硼复合材料的冲击强度和热导率比纯环氧树脂（EP）的分别提高了133%和171%。随着未来的基板材料要求有效的热耗散,这种复合材料有望用于微电子工业上。     

环氧树脂改性聚氨酯耐热性能的研究

端异氰酸酯基聚氨酯预聚体与环氧树脂E-51形成了互穿网络,通过热重分析仪(TGA)研究了完全固化后的互穿网络的热分解行为、透射电镜研究了IPN的相分离行为,及拉伸强度、硬度等对其进行了表征。结果表明,经过环氧树脂改性的聚氨酯的耐热性能比纯聚氨酯得到了提高,且力学性能也有所改善,并对其机理进行了阐述。     

氰酸酯改性环氧树脂耐热性研究

采用热变形仪和红外光谱研究了氰酸酯树脂(CE)改性环氧树脂(EP)体系的4种不同配比和不同固化温度对产物的耐热性的影响。结果表明:加入CE树脂能显著提高EP的耐热性,但固化温度对CE树脂含量不同体系的热变形温度(HDT)影响程度有明显差别。CE/EP体系中EP过量时,提高固化温度,产物的HDT显著提高,在230℃以上固化反应才能完成;两者相当或CE过量时,固化温度在180～200℃时产物的HDT最高,提高固化温度,产物的HDT反而下降。CE含量不同时,反应生成的产物各异,这是造成固化物HDT差异的根本原因。     

高耐热透明阻燃环氧树脂固化体系研究

在以双酚A/四溴双酚A混合环氧树脂(EP)与甲基六氢邻苯二甲酸酐(MeHHPA)构成的胶料基础上,通过加入氯桥酸酐,制备出了具有良好耐热性和阻燃性的透明EP固化物。结果表明:与未加入氯桥酸酐体系相比,当w(氯桥酸酐)=20%(相对于固化剂质量而言)时,EP固化物的总燃烧时间由21 s降至2 s,而氧指数由31%增至37%,玻璃化转变温度(Tg)从123℃提高到148℃,负荷热变形温度(HDT)从108℃增加到129℃。     

橡胶增韧环氧树脂的研究

以羧基丁腈橡胶、聚硫橡胶和羟基聚硅氧烷为增韧剂,以冲击强度、弯曲强度和拉伸剪切强度来评价环氧树脂的增韧效果。实验结果表明,加入增韧剂后的各配方韧性相对于对照组均有不同程度的提高;液态聚硫橡胶增韧的环氧树脂胶表现出良好的抗冲击性能和抗弯曲性能;羧基丁腈橡胶增韧的环氧树脂胶表现出良好的拉伸剪切性能。     

Simultaneous reduction and surface functionalization of graphene oxide for enhancing flame retardancy and thermal conductivity of mesogenic epoxy composites

Graphene oxide (GO ) is reduced and surface functionalized by 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide simultaneously. This functional reduced graphene oxide (F‐rGO ) with better thermal stability can be used as a nano‐filler to improve the flame retardancy, mechanical properties and thermal conductivity of mesogenic epoxy (EO ). Due to the presence of an oriented structure, EO is an intrinsic highly thermal conductive polymer compared with common polymer. After being filled with F‐rGO , the ordered domains in the EO matrix are connected by F‐rGO . As a result, the thermal conductivity coefficient of F‐rGO /EO composite is increased by 30.8% compared with pure EO . The dynamic mechanical analysis results indicate that E ' of F‐rGO /EO is 26.7% higher than that of EO . Because of the stable structure of F‐rGO , F‐rGO /EO is self‐extinguishing. The total heat release of F‐rGO /EO ‐15 is 24.1 kJ g^?1, which is 5.6 kJ g^?1 lower than that of EO . © 2016 Society of Chemical Industry