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。     

Miscibility, morphology, thermal, and mechanical properties of a DGEBA based epoxy resin toughened with a liquid rubber

Epoxy resin based on diglycidyl ether of bisphenol A and varying content of hydroxyl terminated polybutadiene were cured using an anhydride hardener. The ultimate aim of the study was to modify the brittle epoxy matrix by liquid rubber to improve the toughness characteristics. Chemorheological analysis of the modified network was performed to understand the physical transformations taking place during the cure polymerization reaction. The delay in gel time on inclusion of rubber can be explained by lower reactivity due to dilution and viscosity effect. Tensile, flexural, and fracture toughness behaviors of neat as well as modified networks have been studied to observe the effect of rubber modification. The morphological evolution of the toughened networks was examined by scanning electron microscope, and the observations were used effectively to explain the impact properties of the network having varying content of liquid rubber. Acoustic emission studies were performed on neat and certain modified systems. Based on acoustic emission results and morphological characteristics, toughening and failure mechanisms were discussed. The behavior of the relaxation peaks were evaluated by dynamic mechanical analysis and tried to explain the composition of networks. Thermal stabilities of the toughened epoxies were studied using thermogravimetric analysis (TGA). The activation energy for decomposition of neat and modified epoxies has been estimated and compared. The reduction in cross-linking density of the thermoset upon modification has been confirmed and explained.     

丁腈橡胶增韧环氧树脂研究进展

综述了近年来丁腈类橡胶增韧环氧树脂的研究进展,其中包括固体丁腈橡胶,液体丁腈橡胶(丁腈-40液体橡胶,无规端羧基液体丁腈橡胶(CRBN),端羧基液体丁腈橡胶(CTBN),改性端羟基丁腈橡胶(HTBN),改性端氨基液体丁腈橡胶(ATBN))以及改性液体丁腈橡胶与纳米SiO2共同增韧环氧树脂。     

适用于RTM成型的高性能环氧树脂体系的研制

通过优化实验得到了具有室温粘度小于1000 mPa·s,凝胶化和固化时间短,固化时放热量少,有足够的适用时间(室温下适用期大于48 h)等满足RTM成型要求的树脂体系。经拉伸强度、弯曲强度、剪切强度及模量的测试表明该体系具有较好的强韧性。通过扫描电镜照片,表明微观结构均匀致密,树脂基体的湿润性良好,断裂形式为韧性破坏。     

Cure kinetics, morphology and miscibility of modified DGEBA-based epoxy resin - Effects of a liquid rubber inclusion

Kinetics of the curic reaction and morphology of a diglycidyl ether of bisphenol-A based epoxy resin (DGEBA), using an anhydride hardener (nadic methyl anhydride) at different weight contents of carboxyl-terminated copolymer of butadiene and acrylonitrile liquid rubber (CTBN) was investigated using a differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning electron microscopy (SEM). The aim of the work is to understand the effects of inclusion of the liquid rubber phase in the transition phenomena that occur during the curing reaction. The curic reaction at three different curic temperatures and at varying rubber contents in the range of 5-20 wt% has been studied. The reaction rate and conversions that occurred at the curic temperatures were analyzed. The increase in the rate with the curic temperature showed this as a thermally catalyzed reaction. The rate of the reaction was found to decrease in liquid rubber-modified epoxies due to the effect of dilution and viscosity increase as obtained from the gelation times. The experimental data showed an autocatalytic behavior of the reaction, which is explained by the model predicted by Kamal. This model includes two reaction constants k₁ and k₂ and two reaction orders m and n. The order of the overall reaction was found to be approximately 2. The activation energies Ea₁ and Ea₂ were estimated at all curic temperatures for neat and all modified epoxies. The results obtained from the DSC data were also applied to diffusion controlled kinetic models. A schematic model to represent the curic reaction and phase separation was introduced and the molecular mechanism of this curing reaction was discussed. During the curic reaction, phase separation of the liquid rubber from the epoxy matrix took place and the modified epoxies showed phase separated morphology. The dispersed phase showed a homogenous particle size distribution. The size of the phase separated domains increased with increasing concentration of the CTBN and decreased with rise in curing temperature. The glass transition temperature (T_g) of the modified epoxies decreased with increase in curic temperature as studied from dynamic mechanical thermal analysis. Addition of the liquid rubber lowered the T_g of the network. This became prominent in the modification of the matrix with 15 and 20 wt% of the elastomer. This is attributed to flexibilization of the matrix. The dissolved rubber plasticizes the epoxy network. The T_g of the neat rubber in the low-temperature region was shifted to higher temperature upon addition of the elastomer. A higher shift was noted for 15 and 20 phr inclusion. This was due to dissolved epoxy in the rubber-rich phase that increased the modulus of the rubbery phase. The inclusion of a large wt% of carboxyl-terminated butadiene-co-acrylonitrile (CTBN) decreased the cross-linking density of the thermoset matrix.     

Toughening mechanisms of rubber modified thin film epoxy resins

An epoxy terminated polybutadiene (ETPB) was synthesized and utilized to enhance the toughening of an epoxy system, in both bulk and coating states. In the first step, the fracture energy of the modified samples was determined using a single edge notched type specimen in a three point bending (SEN3PB) geometry. The effective toughening mechanisms of bulk epoxy specimens were examined using scanning electron microscopy (SEM). The results showed that plastic void growth, cavitation and shear yielding mechanisms were the main toughening mechanisms of the bulk epoxy systems. In the next step, mechanical properties (i.e. impact resistance, flexibility, cupping resistance and hardness) and adhesion of the thin film specimens were evaluated in accordance to the amount of synthesized ETPB. The results showed that the mechanical properties of the ETPB modified epoxy resins considerably improved. In all cases, it was found that the improvement of the mechanical properties reached a maximum at 7.5 wt.% and then began to decrease with further increase in ETPB content. The effective toughening mechanisms in the modified thin films were also examined using SEM and compared to the bulk types. In contrast to the bulk types, the results showed that crack arresting and shear yielding were active mechanisms in thin films. The contribution of these mechanisms led to the improvement of adhesion and mechanical properties by energy dissipation.     

一种侧链型液晶聚合物与环氧树脂共混改性研究

设计并合成了一种侧链型液晶聚合物（SLCP），用红外光谱（FTIR），差示扫描量热分析（DSC）和偏光显微镜（POM）对聚合物结构和液晶性能进行表征，探讨其对环氧树脂共混物力学性能的影响，并分析共混物的微相分离结构，结果表明，用T31作固化剂时SLCP对环氧树脂有较好的增强增韧效果，在强度和玻璃化温度不降低的情况下断裂伸长度比未改性固化物最大提高2．6倍，但用三乙醇胺作固化剂时SLCP对环氧树脂改性效果不明显。     

硅树脂对硅橡胶耐热性能的影响

用硅树脂对硅橡胶进行改性 ,研究了硅树脂及其含量对硅橡胶耐热性能的影响。通过热空气老化试验及热重法—差热分析表明 :其力学性能与热空气老化性能显著提高。经过 30 0℃× 48h热空气老化后 ,加入硅树脂的试样仍非常柔软 ,性能保持率达 80 %。     

环氧树脂改性含硅自消光水性聚氨酯树脂的制备及性能

以聚己二酸1，4－丁二醇酯多元醇(PBA)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸（DMPA）、1，4-丁二醇（BDO）、端羟丙基聚二甲基硅氧烷(PDMS)和环氧树脂(E-51)为单体合成聚氨酯预聚体，三乙胺（TEA）作为中和剂，乙二胺（EDA）作为后扩链剂，合成了一系列环氧树脂改性含硅自消光水性聚氨酯树脂乳液。采用粒度分析仪测定乳液粒径、FTIR表征胶膜表面结构、SEM观察胶膜表面，并分析了胶膜的光泽度、水接触角、热力学等性能。结果表明：在n(PBA)：n(PDMS)=1:2的条件下，环氧树脂添加量为5 %时，乳液粒径为1152 nm，胶膜60?光泽度为3.4；水接触角为107.3?，疏水性能最优；胶膜拉伸强度可达24.42 MPa，断裂伸长率在362 %，力学性能最优；胶膜热失重50 %时温度较未添加E-51的胶膜提高了18.3 ℃。     

环氧树脂/改性SiC复合材料的制备及性能

采用硅烷偶联剂KH-560和丙烯酰胺对SiC进行表面改性,将其添加到环氧树脂中制备环氧树脂/改性SiC复合材料.采用傅里叶变换红外光谱仪、X射线衍射仪以及接触角测试仪探究改性SiC的性能,并对复合材料的性能进行测试.结果表明:SiC表面带有憎水基团,与环氧树脂相容性提高;SiC用量为环氧树脂质量的20％时,拉伸强度和弯...     

乙烯基改性MDQ硅树脂的合成及其硅橡胶应用

以四甲基二乙烯基二硅氧烷、二甲基二乙氧基硅烷、正硅酸乙酯为原料,通过酸催化水解缩聚反应合成了乙烯基改性MDQ硅树脂,利用红外、核磁共振、X射线衍射对产物进行了表征。测试了将产物用于硅橡胶中的力学性能。结果表明:硅树脂的M/Q值为0.7,乙烯基摩尔分数为0.36%,n(D)/n(M+D+Q)=0.15时,硅橡胶邵氏A硬度58,拉伸强度3.78 MPa,拉断伸长率为152%,撕裂强度38.3 kN/m,该乙烯基改性MDQ硅树脂可用于硅橡胶补强。     

Natural inorganic nanotubes reinforced epoxy resin nanocomposites

Natural occurred nanotubes, halloysite nanotubes, were modified by silane and incorporated into epoxy resin to form nanocomposites. The morphology of the nanocomposites was characterized by transmission electron microscopy (TEM). Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed on the nanocomposites. Flexural property and coefficient of thermal expansion (CTE) of the nanocomposites were also determined. Comparing with the neat resin, about 40% increase in storage modulus at glassy state and 133% at rubbery state were achieved by incorporating 12 wt% modified HNTs into the epoxy matrix. In addition, the nanocomposites exhibited improved flexural strength, char yield and dimensional stability. TEM examination revealed a uniform dispersion of the nanotubes in the epoxy resin. The remarkably positive effects of the HNTs on the performance of the epoxy resin were correlated with the unique characteristics of the HNTs, the uniform dispersion and the possible interfacial reactions between the modified HNTs and the matrix.     

新型环氧树脂软模的制备

以聚醚改性硅油为相容剂,硅橡胶和环氧树脂(EP)混合固化制备了具有较高强度和良好脱模性能的EP软模。红外光谱(FT-IR)分析表明聚醚改性硅油的合成物中含有聚醚与硅油基团,说明反应能够顺利进行;在聚醚改性硅油作用下,硅橡胶与EP具有良好的相容性,并可通过增减硅橡胶的用量来调节模具的强度,同时模具的使用寿命显著增加,使用次数至少为硅橡胶模具的100倍;硬脂酸锌的加入使模具的表面张力降低,脱模性能明显提高,并且已达到菱镁制品的脱模要求。当硅橡胶的质量分数为30%时,加入20%的硬脂酸锌可使模具的表面张力降至24.83×10-5 N/cm。     

十八胺改性环氧树脂研究

通过冲击试验机、热变性仪、硬度计、动态力学分析仪、热重分析仪等仪器研究了十八胺对环氧树脂固化物性能的影响,研究发现十八胺可以提高环氧树脂酸酐固化物的耐冲击性能、硬度改变较小、热变性温度降低。     

纳米有机蒙脱石改性环氧树脂的研究

利用长链的有机阳离子改性天然蒙脱石，制备出有机蒙脱石，用于改性环氧树脂。在有机蒙脱石低含量范围，环氧树脂有机蒙脱石复合物的触变性得到了显著改善；同时将固化产物的热降解温度从380．4℃提高至397．4℃。     

新型改性丁腈橡胶对PVC糊树脂力学性能的影响

通过试验配方设计、样条制备及性能检测,讨论了不同含量的改性粉末丁腈橡胶对PVC糊树脂力学性能的影响.结果表明,随着弹性体用量的增大,软质PVC材料的拉伸强度下降,断裂伸长率得到明显改善.新型改性粉末丁腈橡胶能够改善PVC糊树脂的性能.     

丙烯酸酯液体橡胶改性环氧树脂胶粘剂的研究

以侧链含环氧基团的丙烯酸酯液体橡胶为改性剂 ,二乙撑三胺基甘油正丁基醚为固化剂制备了一种室温固化环氧树脂胶粘剂。重点研究了其粘接工艺性、力学性能和丙烯酸酯液体橡胶的改性作用。研究结果表明 :该胶粘剂具有较好的粘接工艺性能和拉剪强度 ,加入丙烯酸酯液体橡胶后拉伸剪切强度有显著的提高 ;液体橡胶环氧基含量和橡胶添加量对胶粘剂拉剪强度有重要的影响 ,每百份环氧树脂加 10份环氧基含量为 1.2mmol·g-1的丙烯酸酯液体橡胶 ,铝合金胶接试片拉剪强度提高了 133% ,复合材料胶接试片拉剪强度提高了 12 4 % ,4 5 # 钢胶接试片拉剪强度提高了 84 %。     

CA型环氧树脂固化剂性能研究

用ＩＲ光谱表征了自制ＣＡ型环氧树脂固化剂的结构特点,测定了ＣＡ型固化剂的固化特性,固化树脂的性能和增塑效果。实验结果表明,ＣＡ型固化剂能使环氧树脂涂料在潮湿表面和带油表面上固化成膜,其固化的树脂具有良好的耐蚀性,冲击强度较二乙撑三胺固化的树脂有较大提高,同时也是一种较好的环氧树脂用增塑剂。     

端羟基聚醚改性环氧树脂研究

合成了不同分子量(450,1200,2000)的端羟基聚醚(mPEG)改性双酚A型环氧树脂,通过DSC、动态热机械分析(DMA)研究了mPEG/EP的固化反应活性及改性环氧树脂酸酐固化体系的热性能与冲击性能进行了研究,并用扫描电子显微镜(SEM)分析了冲击试样断面。结果表明,改性体系的固化反应活性略有降低;在mPEG含量为15%时固化体系的冲击韧性都达到最大值;改性环氧树脂固化体系的玻璃化转变温度(Tg)随mPEG的含量增大有所降低,且相同质量下mPEG分子量越小下降幅度越大。     

基体种类对CTBN改性环氧树脂结构和性能的影响

研究了ＣＴＢＮ对不同种类的环氧树脂（Ｅ－５１、Ｆ－５１）力学性能的影响,通过扫描电镜观察了２种增韧体系的微观结构形态,并探讨了２种增韧体系的微观结构形态与力学性能间的关系。