Recent Developments on Epoxy-Based Thermally Conductive Adhesives (TCA): A Review

The development of new polymer-based conductive adhesives with specific performances and improved conductivity are increasingly critical for thermally interface material (TIM). Epoxy resins have been widely used as a common interface material for conductive adhesives due to its well-known ability to accept wide range of fillers possibly derived from carbon, metallic or ceramic sources. These conductive fillers with high inherent thermal conductivity, together with a possibility to characterize and manipulate the system, leads to the production of thermally conductive adhesives with higher knowledge content for a number of electronics applications.     

SnO_2-Sb_2O_3-TiO_2导电粉末及其导电涂层的制备

以TiO2为基体,采用化学共沉淀技术制得复合导电粉末。利用正交试验得到优化的制备条件:复合反应体系组成为m(TiO2)∶m(SnCl4)∶m(SbCl3)=25∶15∶1,pH值为1.5,水解温度60℃,沉积SnCl4和SbCl3的水解产物于TiO2粒子表面,得到的包覆物在700℃下焙烧30 min,制备的复合导电粉末体的电阻率为77Ω.cm,粒径≤200 nm。将导电粉末与粘结树脂经球磨分散制得具有良好流动性的涂布液,在铝箔上能够制备得到电阻率低于108Ω.cm的导电涂层,满足制备有机光导体的要求,涂层表面平滑,无凹凸等缺陷。     

导电橡胶电阻率稳定性研究

研究了乙炔炭黑和超导炭黑填充天然橡胶（ＮＲ）、丁腈橡胶（ＮＢＲ）和三元乙丙橡胶（ＥＰＤＭ）胶料的基本电性能和物理机械性能。实验结果表明，胶料电阻率在老化后均有不同程度的下降：测试环境温度发生变化时，胶料电阻率随着热能的吸收呈下降趋势。     

协同交联型大豆胶黏剂的流变与固化性能研究

利用饲料级大豆粉为原料,通过水性聚酰胺和异氰酸酯对其进行协同复合改性制备出具有良好流变行为和固化性能的大豆胶黏剂。采用旋转流变仪研究了复合改性剂用量对大豆胶黏剂流变行为和固化性能的影响,结果表明：改性后的大豆胶黏剂属于假塑性流体,当水性聚酰胺添加量为10%时,所得大豆胶黏剂的流变性能较优,而异氰酸酯添加量对大豆胶黏剂的流变行为几乎没有影响;运用动态温度扫描模式研究大豆胶黏剂的黏弹性能,异氰酸酯添加量对大豆胶黏剂的储能模量和损耗模量影响较大。水性聚酰胺/异氰酸酯协同交联体系可与大豆蛋白分子间发生交联,当10%水性聚酰胺和4%异氰酸酯协同改性时,所得胶合板的胶合强度可达0.74 MPa,满足国家Ⅱ类胶合板使用要求（≥0.70 MPa）。     

HDPE／无烟煤导电复合材料的制备与性能研究

以氯化铜熔盐掺杂无烟煤为导电填料 ,并通过偶联剂界面处理 ,与高密度聚乙烯熔融共混 ,成功制备了HDPE/无烟煤导电复合材料 ,通过力学性能测试、扫描电镜观察、电导率测试等手段研究了其结构与性能。结果表明 :复合材料拉伸强度在填充量 2 0 %以内均高于基体树脂 ,在 10 %附近取得最大值 ;断裂伸长率有所下降 ,但仍高于10 0 % ;电阻率变化符合逾渗规律 ,在填充量为 15 %时 ,电阻率下降到 2 .2 4× 10 7Ω·cm ,达到了抗静电材料的要求     

结构型与复合型导电塑料研究进展

概述了导电塑料的重大发现,阐明了塑料的导电机理和导电渗滤阈值,分析了不同加工工艺、不同导电炭黑、不同聚合物体系对材料导电性能和力学性能的影响,介绍了纳米技术在导电聚合物中的应用,综述了国内外结构型与复合型导电塑料最新技术成果、应用领域和研究进展。     

Development of Polypyrrole/Epoxy Composites as Isotropically Conductive Adhesives

As a possible replacement for lead bearing solders, metal filled isotropically conductive adhesives (ICAs) have shown a lot of potential recently. But still they have to come a long way and overcome their limitations like low impact strength and moisture instability. The current paper attempts to address the limitations of these ICAs by using intrinsically conducting polymer as a filler in place of metals. Conducting polymer (CP) polypyrrole (PPy) was incorporated as a filler in an epoxy/anhydride (EP) system and its application as an isotropic conductive adhesive was studied. PPy was synthesized by chemical polymerization using dodecyl-benzene sulphonic acid (DBSA) as dopant. The composites with varying PPy concentrations were studied for curing behavior and thermal degradation properties using DSC and TGA, respectively. The composites show good impact properties and conductivity at very low filler concentrations. SEM observations established that PPy particles were dispersed in the epoxy matrix uniformly. The overall characteristics of these conductive adhesives establish that they can be used as conductive adhesives in the electronics industry.     

薄膜开关用低温固化导电银浆的研究及应用

研究了不同银粉含量、银粉形貌、银粉粒径对导电银浆电性能的影响,对比不同树脂粘结相对导电银浆电性能及对银粉润湿性的影响,探讨不同固化条件对导电银浆电阻率的影响。以自制聚氨酯为树脂粘结相,探讨了导电银浆的耐弯折性能。结果表明,以片状银粉和球状银粉混合使用作为导电相的导电效果好于两者单独使用时的导电效果。实验证明了聚氨酯为树脂粘结相的导电银浆对银粉的润湿性较好,且耐弯折性能较佳。     

碳纤维对导电混凝土性能和微结构的影响

导电混凝土较好的导电性能,可用于道路工程除冰,保障交通通行安全.采用碳纤维制备导电混凝土,观察其性能和微结构的变化.研究结果表明:碳纤维的掺用使得混凝土拌合物的工作性变差,但仍然能满足施工要求.随着碳纤维掺量的增加,导电混凝土的抗压强度下降,但劈拉强度增大.导电混凝土的电阻率随碳纤维掺量的增大而降低,持续通电后,呈良好的电热效应和发热效果.掺加碳纤维后,水泥石结构的密实性降低,从而导致其性能发生变化.     

Thermoset Matrices for Structural Adhesives: Imidazole-Catalysed Curing of Epoxy Resins

The thermoset epoxy systems of diglycidyl ether of bisphenol-A (DGEBA) and different imidazoles (unsubstituted imidazole, N-methyl-im., 2-methyl-im., 4(5)-methyl-im., 2-ethyl,4-methyl-im., 2-ethyl-im., 2-phenyl-im.) as catalytical curing agents were characterized. From microcalorimetric experiments it was deduced that each molecule of imidazole induces more than 20 epoxy groups to undergo polyaddition. Therefore, optimum glass transition temperature-ranges can be obtained with 0.025 to 0.05 mol of catalyst/equivalent of epoxy. The different alkyl-and aryl-substituted imidazoles show rather similar catalytic effects, with the kinetics differing by a factor of 3 at most. Mechanical properties (flexural modulus and strength, ultimate strain and fracture toughness) at ambient temperature do not correlate with the crosslinking density of the polymer network.     

交联剂用量对导热硅橡胶性能的影响

以α,ω-二羟基聚二甲基硅氧烷为基胶,制备了缩合型单组分室温硫化导热硅橡胶。研究了交联剂用量对导热硅橡胶施工性能、力学性能、电绝缘性能和导热性能及储存稳定性的影响。结果表明,当交联剂用量为2.5~3.0份时,导热硅橡胶具有最佳的使用性能和储存稳定性。     

炭黑预处理对炭黑／HDPE导电复合材料性能的影响

通过用四种有代表性的处理剂对炭黑进行预处理，研究了处理后炭黑填充的HDPE复合材料的电性能、力学性能和流变性能。发现四种处理剂对复合材料的性能均有一定的改善。但也表现出各自的差异，在导电性能上表现的差异更为明显，如经钛酸酯偶联剂和硬脂酸处理的炭黑，在炭黑含量为15%时，可使复合材料的电阻率降低1-2个数量级。为此笔者分析了上述结果的原因。     

导电填料对粉末涂料导电性能的影响

研究了使用三类不同导电填料制得的粉末涂料的表面电阻与导电填料含量的关系，确定了粉末涂料中各类导电填料的渗滤阔值。用扫描电镜（SEM）观察了不同导电填料含量的粉末涂料的断面形貌，用透射电镜（TEM）观察分析了炭黑及导电二氧化钛的结构及粒径。结果表明，填料不同，得到的粉末涂料的渗滤阈值有很大差别。对于炭黑或导电二氧化钛，其结构性越高，比表面积越大，粒径越小，导电性能越好，得到的渗滤阈值越低。     

填充型丙烯酸树脂导电银浆电性能的研究

研制了一种银粉填充丙烯酸树脂的复合导电银浆，讨论了导电填料银粉的含量、粒径大小、形状对导电银浆导电性能的影响。分析了偶联剂以及固化条件对导电银浆导电性能的影响。     

水中固化环氧树脂胶黏剂制备与性能研究

以固化剂、偶联剂及水泥用量,填料种类及其用量、促进剂及其用量等因素为考察对象,进行正交实验设计,考察了环氧胶黏剂中各组分用量对其剪切粘接强度的影响,并测试了其粘接性能及动态黏弹力学性能,同时进行了傅立叶红外光谱(FTIR)结构表征和热重(TGA)分析。通过粘接性能测试,得到了自制固化剂复配环氧树脂及不同助剂的最优配方:环氧树脂100份、固化剂30份、偶联剂5份、水泥120份、填料10份、促进剂2.8份,该环氧胶黏剂的剪切粘接强度为22.0MPa左右,拉伸强度为12.50MPa左右,冲击强度为9.41kJ/m2。TGA表明:环氧胶黏剂在低于335℃时,热稳定性比较好,保留率为90%以上。DMA测试得到:该胶玻璃化温度Tg为50℃左右。通过探索,混凝土哑铃型试件水中固化环氧胶黏剂的拉伸粘接强度达2.5MPa以上。     

严苛侵蚀作用对优化导电混凝土性能的影响

干湿交替和硫酸盐腐蚀引起的损伤严重影响导电混凝土服役时的长期稳定性。本研究以碳纤维、石墨作为导电相材料,掺入粉煤灰和硅灰制备导电混凝土,在干湿交替和硫酸盐腐蚀耦合作用下,讨论粉煤灰、硅灰掺量对导电混凝土力学性能与电学性能的影响。综合导电混凝土的力学性能与电学性能衰变定义了服役性能劣化指标。结果表明：掺入粉煤灰和硅灰后提升了导电混凝土在干湿交替和硫酸盐腐蚀下的耐久性和导电稳定性;当粉煤灰和硅灰的总掺量一定时,提高粉煤灰占比能够有效降低干湿交替和硫酸盐腐蚀造成的强度损失,并提高导电混凝土的导电稳定性。     

硫化剂对硅橡胶性能的影响

考察硫化剂TX-29、双2,5、双2,4和DCP对硅橡胶硫化特性和物理性能的影响。试验结果表明:采用硫化剂DCP的硅橡胶的综合物理性能最佳;可根据生产工艺、成本和性能要求,选用不同的硫化剂来实现产品性能目标。     

PBT基浅色导电母粒的制备及性能研究

以聚对苯二甲酸丁二醇酯(PBT)和导电TiO₂为原料,硬脂酸镁为分散剂,利用熔融混合的方法制备导电母粒。采用扫描与透射电镜、高阻仪等测试手段,重点分析了导电TiO₂及分散剂含量对导电母粒的电性能及颗粒分散性的影响。结果表明:随着导电TiO₂含量的增加,导电母粒的电阻率逐渐下降,当TiO₂质量分数大于65%时,电阻率变化趋缓;当分散剂质量分数在1.0%左右时,导电TiO₂的颗粒分散情况较好,且体积电阻率也处于相对较低的水平。     

Room Temperature Curing Epoxy Adhesives for Elevated Temperature Service,Part II: Composition,Properties, Microstructure Relationships

Low temperature curing epoxy formulations for elevated temperature service have been previously developed and studied (Part I¹). Balanced performance with respect to shear and peel properties have been obtained for a system composed of a tetra and trifunctional epoxy blend crosslinked by a mixture of multifunctional amine and an amino-terminated elastomer. In continuation of the previous study, the present one is aimed at investigation the effect of substitution of difunctional epoxy resin and curing agent for trifunctional ones on the developing microstructure and resulting mechanical properties. Furthermore, a new type of amino-terminated-acrylonitrile (ATBN) and an epoxy-terminated silane were included in the present investigation. Experimental results show that while reduction in the overall functionality of the reactants results in a lower lap shear strength, it gives rise to enhancement in peel strength. The same effect was observed when the new ATBN was used. Thermal analysis of the polymerization processes, taking place during curing of the various low temperature curing formulations, indicates that the curing activation energies are appreciably lower compared with high temperature curing systems. Addition of silane, ATBN and substitution of the multifunctional amine curing agent by a lower functional one, resulted in a moderate increase in the activation energy. The basic formulation, comprising a tetra- and trifunctional resin blend and a multifunctional amine and ATBN crosslinking mixture, developed a typical two-phase matrix-rubber microstructure. A third phase was observed when the trifunctional epoxy resin or the multifunctional curing agent was substituted by lower functional ones. A similar three-phase morphology was obtained when the epoxy-terminated silane was added to the basic treta- and trifunctional reactant system.     

二段硫化条件对均聚氯醚橡胶(CO)性能的影响

研究了二段硫化条件(硫化温度和硫化时间)对均聚氯醚橡胶(CO)基本性能和压缩永久变形性能的影响。结果表明,二段硫化温度越高,硫化时间越长,胶料的拉伸强度和定伸应力越大,硬度越高;而撕裂强度、伸长率、拉断永久变形以及压缩永久变形越小,其中胶料的硬度、拉伸强度、伸长率、压缩永久变形在一定时间后基本上趋于平衡,较好的二段硫化条件为150℃～160℃×3～4h。