反应型有机修饰剂对环氧树脂/粘土纳米复合材料热/机械性能的影响

使带有环氧基团的三缩水甘油基对氨基苯酚(TGPAP)分别与溴代正丁烷(BB)、2-溴乙醇(BE)反应,合成了反应型粘土有机修饰剂溴化(正定烷基)双环氧基(4-环氧醚基)铵(TGPAPB)和溴化(2-羟乙基)双环氧基(4-环氧醚基)铵(TGPAPE)。用这两种修饰剂改性粘土,分别制备出具有相同反应官能团但与环氧树脂的相容性略有不同的两种有机化粘土(B-Clay和E-Clay)。再用“粘土淤浆复合法”制备出两种环氧树脂/粘土纳米复合材料,研究了两种反应型有机修饰剂对纳米复合材料的结构和性能的影响。结果表明：带有羟基的E-Clay以高度无规剥离形式均匀分布在环氧树脂基体中;而B-Clay则形成了无规剥离/插层混合结构。两种粘土均参与固化反应在环氧树脂基体和粘土片层间产生了较强的界面作用力,从而显著提高了纳米复合材料的拉伸强度。粘土质量分数为3%的两种纳米复合材料,其拉伸强度分别达到32.4 MPa(E-Clay)和28.0 MPa(B-Clay),比对应的纯环氧树脂聚合物分别提高了76.47%和52.51%。同时,这两种纳米复合材料的玻璃化转变温度(T_g)也略有提高。     

剥离型环氧树脂/粘土纳米复合材料热/力学性能

以质子化的2,4,6-三(二甲氨基甲基)苯酚(DMP-30)作为有机修饰剂对原始粘土进行改性,采用"粘土-丙酮淤浆复合法"合成了环氧树脂/粘土纳米复合材料。透射电镜观察显示粘土片层以3~5片为聚集单元均匀、无规地分布在整个环氧树脂的基体中,呈现高度、无规剥离形态。差示扫描量热测试表明粘土质量分数为3%时的环氧树脂/粘土纳米复合材料的Tg提高了10℃,这归咎于无规剥离结构及粘土片层与环氧树脂基体间较强的界面作用力。弯曲试验揭示,室温条件下纳米复合材料的弯曲强度随着粘土含量的增加而呈缓慢下降趋势;而在80℃时,弯曲强度则随粘土的加入而显著增加。     

有机粘土/聚醚砜/环氧树脂杂化纳米复合材料的制备和性能

分别用溶剂法和熔融法成功制备了有机粘土/聚醚砜/环氧树脂杂化纳米复合材料,对其拉伸性能、断裂韧性、热性能和微观结构进行了研究。结果表明:两种杂化纳米复合材料的拉伸强度可达75 MPa以上,模量可达3.0 GPa以上,断裂韧性可达1.1 MPam1/2以上。观察到了聚醚砜和有机粘土对环氧树脂的协同增韧现象。聚醚砜/环氧树脂基体具有半互穿网络结构,有机粘土片层呈有序剥离形态。用溶剂法制备的杂化纳米复合材料样本的玻璃化转变温度(Tg)在170℃以上,用熔融法制备的样本的Tg在180℃以上。     

纳米粘土/环氧树脂复合材料的制备及力学性能研究

借助超声分散,采用固化处理制备了不同纳米粘土掺量(0,1%,3%,5%和7%(质量分数))的纳米粘土/环氧树脂复合材料,研究了纳米粘土掺量对复合材料性能的影响。通过X射线衍射(XRD)、力学性能测试、扫描电镜(SEM)等对复合材料进行了表征。结果表明,不同掺杂比例的纳米粘土和环氧树脂都均匀结合,纳米粘土掺量为7%(质量分数)的复合材料衍射峰强度最高,其结晶性能最佳;随着纳米粘土掺量的增加,复合材料的拉伸模量、极限抗压强度和断裂韧性KIC值整体均高于纯环氧树脂,而复合材料的破坏应变低于纯环氧树脂;当纳米粘土掺量为1%(质量分数)时,复合材料的极限抗拉强度略有提高,但随着纳米粘土掺量的继续增加,复合材料的极限抗拉强度逐渐降低;当纳米粘土掺量为5%(质量分数)时,复合材料的拉伸模量达到3 513 MPa,相比纯环氧树脂的3 300 MPa,增加了6.5%;当纳米粘土掺量为7%(质量分数)时,复合材料的断裂韧性KIC值达到1.97 MPa·m~(1/2),相比纯环氧树脂的1.60 MPa·m~(1/2),增加了23.1%;纯环氧树脂的断裂表面光滑无褶皱,断裂时裂纹没有产生无偏离的扩展,而复合材料的断裂表面随纳米粘土掺量的增加均趋于粗糙,裂纹在扩展过程中发生了偏移。     

邻甲酚醛树脂/邻甲酚醛环氧/氧化石墨烯复合材料

为改进酚醛固化环氧树脂复合材料的性能,合成了邻甲苯酚醛树脂(o-CFR)、邻甲酚醛环氧树脂(o-CFER)和氧化石墨烯(GO),制备了o-CFR/o-CFER/GO玻璃钢复合材料,研究了不同含量的氧化石墨烯对复合材料物理力学性能的影响。结果表明,GO加入可以改善材料的力学性能、耐热性能和电绝缘性能。当酚醛与环氧质量比为4∶6,材料中加入1.2%的GO时,起始分解温度(Tid)提高了91℃,复合材料的拉伸强度和冲击强度分别提高了102%和86%;加入2.0%时材料玻璃化转变温度(Tg)可提高19℃。     

化学接枝对碳纤维结构及其复合材料的影响

以丙二酸环(亚)异丙酯和多乙烯多胺对碳纤维进行化学接枝反应,并制备了碳纤维/环氧树脂(CF/EP)复合材料。利用红外光谱、X射线光电子能谱、扫描电镜、动态力学分析对碳纤维和CF/EP复合材料进行表征和测试,研究了复合材料的力学性能,分析比较了2种接枝反应对碳纤维结构及复合材料界面结合的影响。结果表明,碳纤维表面分别成功接枝了-COOH和-NH2,且多乙烯多胺的接枝反应对碳纤维表面和CF/EP复合材料断面产生的效果更为突出,2种复合材料的拉伸强度分别提高了4.4%和17.5%,Tg分别提高了3.1℃和8.2℃,多乙烯多胺的接枝反应对改善界面更具优势。     

纳米粘土/炭黑双相填料对天然橡胶性能的影响

以有机纳米粘土替代部分炭黑,在材料内部引入形状各向异性的纳米片层,制备天然橡胶/炭黑/纳米粘土复合材料,研究了粘土含量对复合材料静态力学性能、动态力学性能、热稳定性、老化性及拉伸疲劳性能的影响。结果表明,以少量有机纳米粘土(2 phr～6 phr)替代部分炭黑可提高天然橡胶的硫化效率,增强复合材料的静态力学性能,降低动态损耗因子,提高复合材料的热稳定性、耐热空气老化性能及拉伸疲劳性能。与纯炭黑试样相比,复合材料拉伸强度最高提高91%,拉伸疲劳寿命提高31%,达55万次。     

纳米SiO_2/环氧树脂复合材料的制备方法与性能关系

采用超声分散、机械剪切搅拌和纳米SiO_2粒子表面处理等多种分散工艺,制备了纳米SiO_2/环氧树脂复合材料。采用SEM、电子拉力机、粘弹谱仪和脉冲声管测试系统分别研究了纳米SiO_2/环氧树脂复合材料的微观结构、拉伸性能、动态力学性能和水声性能。结果表明,超声波分散法以及预处理法能够将纳米SiO_2粒子均匀分散在环氧树脂基体中,并且SiO_2粒子呈纳米尺度分布在环氧基体中。相对纯环氧树脂材料,纳米SiO_2/环氧树脂复合材料的拉伸强度提高了5%—30%,伸长率提高了2%—14%;储能模量随纳米SiO_2粒子的加入与均匀分散而提高,损耗因子则略有下降;吸声系数相对纯环氧树脂材料提高了6—10倍;而且纳米SiO_2/环氧树脂复合材料的常规力学性能、动态力学性能以及水声性能受纳米粒子的分散效果影响明显,分散越均匀,变化越大。     

环氧树脂/粘土纳米复合材料的制备与性能研究

研究了有机蒙脱土在环氧树脂中的插层和剥离行为,制备了两种环氧树脂/蒙脱土纳米复合材料并测试了其力学性能。实验结果表明,环氧树脂与有机土的相容性好,二者混合时环氧树脂很容易插入到粘土层间。使用经不同有机阳离子处理的两种有机蒙脱土,分别制得插层型和剥离型环氧/粘土纳米复合材料,力学性能结果表明,剥离型纳米复合材料的性能优于同组成的插层型纳米复合材料。     

功能化纳米氧化石墨烯/POE-g-MAH/聚苯乙烯复合材料的制备与性能

利用硅烷偶联剂(APTES)对氧化石墨烯(GO)进行功能化改性, 在不同的试验条件下制备了3种硅烷偶联剂功能化GO(APTES-g-GO)纳米填料, 并经熔融共混制备了APTES-g-GO填充改性的聚苯乙烯(PS)复合材料。为了改善复合材料的界面作用, 采用马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)为增容剂。分别采用FTIR、XRD、TG、SEM以及拉伸和冲击测试对填料和纳米APTES-g-GO/POE-g-MAH/PS复合材料的结构和性能进行了表征和测试。结果表明:APTES已成功接枝于GO的表面上。接枝过程中, APTES对GO有一定的剥离和还原作用。随着填料含量的增加, 纳米APTES-g-GO/POE-g-MAH/PS复合材料拉伸强度和冲击强度均先上升后下降。当填料与基体质量比为0.75%时, 3种复合材料的拉伸强度和冲击强度都达到最大值, 其中纳米AS-GO/POE-g-MAH/PS复合材料的综合性能最好, 其拉伸强度和冲击强度比POE-g-MAH/PS分别提高了19%和 31%。共混过程中, APTES-g-GO与POE-g-MAH之间的反应改善了纳米APTES-g-GO/POE-g-MAH/PS复合材料的界面相互作用。APTES-g-GO均匀分散于复合材料中, 它的加入提高了复合材料的热稳定性能。添加AS-GO填料的复合材料热稳定性能提高最为明显, 含0.75% AS-GO的纳米AS-GO/POE-g-MAH/PS复合材料的最大失重温度比POE-g-MAH/PS提高了7 ℃。      

海水环境下老化周期对T800碳纤维/环氧树脂复合材料的影响EI北大核心CSCD

研究T800碳纤维/环氧树脂基复合材料在海水环境中进行湿热腐蚀老化,将制备好的试件放置在人工制备70℃,3.5%NaCl溶液中腐蚀30,60,90 d,通过质量变化、老化前后表面形貌、红外光谱、动态力学性能、压缩实验和层间剪切实验分析材料的力学性能变化。结果表明:T800碳纤维/环氧树脂复合材料在3.5%NaCl溶液中吸湿率分别为0.39%,0.47%,0.53%;未老化试样纤维与基体之间黏结良好,在3.5%NaCl溶液老化后纤维与基体界面破坏随时间的增加老化更加严重;玻璃化转变温度T_(g)下降,分别在老化30,60,90 d后从189.16℃下降到177.54,171.88,168.06℃;经3.5%NaCl溶液老化后,老化30,60,90 d试样的最大破坏载荷分别降低3.2%,8.4%,15.3%,压缩强度分别降低3.0%,8.2%,15.9%;层间剪切最大破坏载荷分别降低3.0%,9.2%,14.9%,剪切强度分别降低3.0%,9.7%,16.4%。     

Investigation of the mechanical properties of DGEBA-based epoxy resin with nanoclay additives

The present study investigated the effect of nanoclay additives on the mechanical properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The resin was cured with diethyltoluene diamine (DETDA) hardener and four material variations produced through the addition of four types of nanoclays, respectively. The nanocomposites were prepared by the in situ polymerisation method with the aid of mechanical shearing. The properties of the nanocomposites investigated included tensile modulus, tensile strength, tensile strain and fracture toughness (K_IC). It was observed that while the addition of nanoclay significantly increased the elastic modulus and fracture toughness of DGEBA epoxy resin, it also significantly reduced the failure strength and failure strain with increasing nanoclay level. Possible mechanisms for the improvement and degradation of these properties of the epoxy–clay nanocomposite materials are discussed.     

On the experimental and numerical investigation of clay/epoxy nanocomposites

Due to increasing use of clay/epoxy nanocomposites in industry, investigation of mechanical properties of clay nanocomposites has become of great interest. While the stiffening mechanism of clay nanocomposites is well documented, there is still not a clear understanding about how addition of clays affect the fracture behavior of clay/epoxy nanocomposites. The main aim of this paper is to measure and explain the effect of clays on ductility reduction of these nanocomposites. First, epoxy and clay/epoxy nanocomposites with different clay weight ratio were built. Then, the damage parameters of epoxy and clay/epoxy nanocomposites were measured by variation of the elasticity modulus. Based on loading–unloading experiments, the Lemaitre damage parameters for epoxy and clay/epoxy nanocomposites were extracted. Crack initiation and propagation in dog-bone sample were simulated for epoxy and clay/epoxy nanocomposites using the eXtended Finite Element Method (XFEM). The comparison between experimental and numerical results shows that the proposed method can predict the crack initiation location and propagation path in clay/epoxy nanocomposites.     

液体天然橡胶对湿法混炼制备白炭黑/天然橡胶复合材料界面相互作用的影响

采用液体天然橡胶（LNR）作为增容剂,通过湿法混炼工艺制备白炭黑/天然橡胶（SiO₂/NR）复合材料。利用SEM、橡胶加工分析仪（RPA）、差示扫描量热分析仪（DSC）、溶胀法和核磁共振交联密度仪分别对改性前后SiO₂/NR复合材料的界面形态、Payne效应、玻璃化转变温度（T_g）、结合胶含量及交联密度进行分析,研究LNR对NR与SiO₂相互作用的影响。结果表明,采用LNR改性后,SiO₂/NR复合材料中SiO₂与NR结合紧密,两相界面变得模糊,断面表现为韧性断裂。一定SiO₂用量下,SiO₂/NR复合材料Payne效应明显减弱。当SiO₂与NR质量比为60：100时,玻璃化转变温度（T_g）由-59.57℃提高到-56.61℃,结合胶含量由40.24%增加到44.02%。Lorenz-Park方程定量计算表明,经LNR改性后,SiO₂/NR复合材料界面相互作用增强。核磁共振测试结果表明,改性后,SiO₂/NR复合材料交联密度增加,横向松弛时间（T₂）减小,SiO₂与NR质量比分别为30：100、50：100和70：100时,T₂分别缩短4.20 ms、5.84 ms和7.86 ms,SiO₂与NR相互作用增强,NR分子链运动受限。LNR具有较好的增容效果,经LNR改性的SiO₂/NR复合材料界面相互作用增强。     

A COMPARATIVE STUDY OF THE PREPARATION AND CHARACTERIZATION OF AROMATIC AND ALIPHATIC BISMALEIMIDES TO PRODUCE MODIFIED SILICONIZED EPOXY INTERCROSSLINKED MATRICES FOR ENGINEERING APPLICATIONS

A novel hybrid intercrosslinked network of hydroxyl-terminated polydimethylsiloxane modified epoxy and bismaleimides [N,N'-bismaleimido-4,4'-diphenylmethane and 1,6-bis(maleimido)hexane] matrix systems were developed. Epoxy resin was modified with 5, 10, and 15% (wt%) of hydroxyl-terminated polydimethylsiloxane using γ-aminopropyltriethoxysilane as crosslinking agent and dibutyltindilaurate as catalyst. The reaction between hydroxyl-terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15% (wt%) of both aromatic and aliphatic bismaleimides separately. The castings and E-glass fiber-reinforced composites prepared were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were also performed to determine the glass transition temperature (T_g) and thermal degradation temperature of the hybrid intercrosslinked systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy resin improves the toughness and thermal stability, with reduction in strength and modulus values. The incorporation of aromatic bismaleimide into epoxy resin improved both tensile strength and thermal properties, whereas it was observed that the incorporation up to 5% of aliphatic bismaleimide into epoxy resin decreased the stress-strain value and above 5% increased the strength properties. However, the introduction of both aromatic and aliphatic bismaleimides (aromatic and aliphatic) into siliconized epoxy resin influenced both mechanical and thermal properties according to the percentage content.     

Mechanical and thermal behavior of non-crimp glass fiber reinforced layered clay/epoxy nanocomposites

Mechanical and thermal properties of non-crimp glass fiber reinforced clay/epoxy nanocomposites were investigated. Clay/epoxy nanocomposite systems were prepared to use as the matrix material for composite laminates. X-ray diffraction results obtained from natural and modified clays indicated that intergallery spacing of the layered clay increases with surface treatment. Tensile tests indicated that clay loading has minor effect on the tensile properties. Flexural properties of laminates were improved by clay addition due to the improved interface between glass fibers and epoxy. Differential scanning calorimetry (DSC) results showed that the modified clay particles affected the glass transition temperatures (T_g) of the nanocomposites. Incorporation of surface treated clay particles increased the dynamic mechanical properties of nanocomposite laminates. It was found that the flame resistance of composites was improved significantly by clay addition into the epoxy matrix.     

固化剂类型与固化条件对环氧/粘土纳米复合材料插层剥离行为的影响

本文作者选用了5种不同类型的胺类固化剂:二乙烯三胺(DETA),二氨基二苯基甲烷(DDM),2.4.6三(二甲氨基甲基)苯酚(DMP-30),增韧改性胺和低温固化改性胺。考察了固化剂类型,固化温度和时间对环氧树脂/粘土纳米复合材料插层剥离行为的影响。固化程度和粘土层间距分别采用FT-IR和XRD,TEM检测。结果表明:环氧/粘土的插层与剥离行为与所选用的五种固化剂类型关系不大,而主要取决于固化工艺参数。在合适的固化条件下,当环氧树脂在粘土层间的固化速度大于层外固化速度,达到基本固化时,就能实现粘土的剥离,得到环氧/粘土纳米复合材料。     

Temperature effects on the fracture behavior and tensile properties of silane-treated clay/epoxy nanocomposites

We investigated the effects of clay silane treatment on the fracture behaviors of clay/epoxy nanocomposites by comparing the compliance, critical fracture load, and fracture toughness of silane-treated samples with those of untreated samples. The fracture toughnesses of untreated and silane-treated clay/epoxy nanocomposites were 8.52 J/m² and 15.55 J/m², respectively, corresponding to an 82% increase in fracture toughness after clay silane treatment. Tensile tests were performed at ?30 °C, 25 °C, 40 °C, and 70 °C. Tensile strength and elastic modulus were higher at ?30 °C than at 25 °C for both samples. However, the tensile properties decreased as temperature increased for both samples. In particular, at 70 °C, the tensile properties were less than 10% of the original value at room temperature, independent of surface treatment. The fracture and tensile properties of silane-treated clay/epoxy nanocomposites increased due to good dispersion of the clay in epoxy and improvement in interfacial adhesive strength between epoxy and clay layers.     

Study on thermal and mechanical properties of nano-calcium carbonate/epoxy composites

A study on evaluating the effect of nano-CaCO₃ particles on thermal and mechanical properties of epoxy resin cast was performed by TGA and mechanical tests. A silane coupling agent KH550 as an interfacial modifier was introduced into nanocomposites through preparing KH550/nano-CaCO₃ master batch. It is revealed that epoxy resin cast filled with nano-CaCO₃ particles represents higher thermal stability and mechanical strength. The improvement of thermal and mechanical properties is attributed to the surface modification of nano-particles, which can enhance the interfacial properties between nano-CaCO₃ fillers and epoxy resin. The mechanical properties of nano-CaCO₃/epoxy/carbon fibres composites based on the modified epoxy matrix are also enhanced.