剥离型环氧树脂/蒙脱土纳米复合材料研究

采用阳离子交换的方法对蒙脱土进行了有机化处理,使蒙脱土由亲水性变成亲油性,并且使其层间距由原来的1.2nm扩大到2.2nm.采用X-射线衍射仪研究了有机蒙脱土在环氧树脂中的剥离行为,制备了环氧树脂/蒙脱土纳米复合材料并测试了其性能.实验结果表明,环氧树脂与有机蒙脱土的相容性好,蒙脱土在环氧树脂中完全剥离;环氧树脂/蒙脱土纳米复合材料的力学性能、热性能以及阻隔性能与纯环氧树脂固化物相比均有不同程度的提高和改善.     

超声波原位插层制备硅树脂/蒙脱土纳米复合材料

采用超声波技术,原位插层聚合法制备了甲基苯基硅树脂/有机蒙脱土(OMMT)纳米复合材料。利用X射线衍射(XRD),透射电镜(TEM)研究了复合材料内部结构以及超声波时间对蒙脱土分散性影响。结果表明,蒙脱土片层间距随着超声波时间延长而增加,当超声波时间短于20min时,有机蒙脱土片层以有序的插层型存在,形成插层型的聚合物/蒙脱土纳米复合材料(PLSN);超声波时间长于30min时,有机蒙脱土片层被剥离,无序地分散在硅树脂基体中,形成剥离型的聚合物/蒙脱土纳米复合材料。     

聚氨酯和蒙脱土协同增韧增强环氧树脂

采用聚合物互穿技术与原位插层聚合相结合的方法制备了有机蒙脱土修饰的环氧树脂/聚氨酯互穿网络纳米复合材料.傅立叶红外光谱,X射线衍射及透射电镜分析表明剥离或插层的蒙脱土片层表面羟基能与环氧树脂/聚氨酯基体发生交联反应,并且均匀分散在环氧树脂/聚氨酯基体中.力学性能测试结果表明聚氨酯,蒙脱土的加入同时增加了环氧树脂的拉伸强度和断裂韧性.扫描电镜分析表明聚氨酯和蒙脱土协同增韧增强环氧树脂的主要原因为剪切屈服和微裂纹增韧.     

桐油酸酐固化环氧树脂/蒙脱土纳米复合材料的研究

通过阳离子交换的方法将蒙脱土进行有机化处理，使蒙脱土由亲水性变成亲油性且层间距扩大，采用浇模固化成型法制备环氧树脂／桐油酸酐／蒙脱土纳米复合材料，并用XRD，DMTA等手段研究有机蒙脱土在环氧树脂中的剥离行为，研究发现，加入桐油酸酐固化剂后，粘土被剥离而得到剥离型的纳米复合材料，而且工艺条件的变化并不明显改变剥离的效果，DMTA测试表明桐油酸酐固化的环氧树脂的玻璃化转变温度随着粘土的加入而降低。     

二维和零维纳米材料协同增强的高性能纳米复合材料

将二维蒙脱土和零维纳米TiO_2共同复合到环氧树脂中,成功地制备出一种高性能有机蒙脱土/纳米TiO_2/环氧树脂复合材料。力学性能测试和热分析显示,该复合材料在拉伸模量、拉伸强度、弯曲模量、弯曲强度、缺口冲击强度、玻璃化转变温度、热分解温度上都明显优于纯环氧树脂,也优于有机蒙脱土/环氧树脂复合材料和纳米TiO_2/环氧树脂复合材料。XRD检测和透射电子显微镜观察显示,在有机蒙脱土/纳米TiO_2/环氧树脂复合材料中,蒙脱土被完全剥离为纳米单片,和纳米TiO_2交错分布于环氧树脂中。选择适宜的两种维度的纳米材料复合于聚合物中,是制备新型高性能复合材料的成功思路。     

脂肪族聚氨酯弹性体/蒙脱土复合材料的制备与性能

使用原位插层聚合法制备了一系列不同有机蒙脱土含量的基于异佛尔酮二异氰酸酯的脂肪族聚氨酯弹性体/蒙脱土纳米复合材料,通过X射线衍射(XRD)、差示扫描量热测试(DSC)、热重分析(TGA)等研究了有机蒙脱土含量对脂肪族聚氨酯弹性体结构与性能的影响。XRD结果表明,成功地合成了聚氨酯/蒙脱土插层型纳米复合材料。TGA结果表明,纳米复合材料的热稳定性随着有机蒙脱土含量的增加而提高。有机蒙脱土对聚氨酯基体有较好的增强和增韧作用,而当有机蒙脱土含量为7%时,纳米复合材料的力学性能最佳。     

EVOH/蒙脱土插层型纳米复合材料的研究

将蒙脱土有机化处理,然后将有机化蒙脱土与乙烯-乙烯醇嵌段共聚物(EVOH)通过Brabender流变仪熔融共混,制得纳米复合材料.通过电子透射显微镜、傅里叶变换红外光谱分析,X射线衍射分析等手段对该复合材料进行了结构测试.结果表明:EVOH可以插入有机化蒙脱土片层间;聚乙烯吡咯烷酮改性蒙脱土被EVOH插开的片层距离比季铵盐改性蒙脱土被EVOH插开的片层距离大;有机化蒙脱土在复合材料中比例越小,复合体系中蒙脱土被插开的片层间距越大;当有机化蒙脱土含量为8%时,形成剥离型纳米复合材料;当有机化蒙脱土含量为15%时,形成插层型纳米复合材料.     

超声波对硅树脂/蒙脱土纳米复合材料热性能的影响

采用超声波技术,原位插层聚合法制备了甲基苯基硅树脂/有机蒙脱土(OMMT)纳米复合材料。X射线衍射(XRD),透射电镜(TEM)研究了复合材料内部结构以及超声波时间对蒙脱土分散性和复合材料热性能的影响。简单控制超声波时间15和30min,分别制备了不同OMMT质量分数的插层型和剥离型聚合物/蒙脱土纳米复合材料。加入OMMT,无论是插层型还是剥离型,复合材料的起始分解温度都有所下降,但热失重速率较平缓。插层型纳米复合材料耐热性能明显优于剥离型,温度500℃时,插层型热失重均小于纯硅树脂。当OMMT含量8%时,插层型PLS复合材料500℃的热失重均10%;而剥离型PLS复合材料500℃的热失重较大,超过15%。     

PMAA/MMT及PMAA/MMT/SiO_2纳米复合材料的结构与性能研究

采用原位插层聚合法制备了聚甲基丙烯酸/蒙脱土(PMAA/MMT)纳米复合材料和聚甲基丙烯酸/蒙脱土/二氧化硅(PMAA/MMT/SiO2)纳米复合材料,并比较两种纳米复合材料的结构与性能。研究结果表明,PMAA/MMT纳米复合材料属于插层与剥离共存型纳米复合材料。PMAA/MMT/SiO2纳米复合材料中蒙脱土的特征衍射峰已经消失,蒙脱土与二氧化硅均匀分散在聚合物基体中。PMAA/MMT及PMAA/MMT/SiO2纳米复合材料均有一定的鞣制性能,但相对而言PMAA/MMT/SiO2纳米复合材料的鞣制效果较好。     

原位乳液插层法制备PBA/OMMT纳米复合母料及其在ABS中的应用

通过原位乳液插层法制备高有机蒙脱土(OMMT)含量的聚丙烯酸丁酯/有机蒙脱土(PBA/0MMT)纳米复合物,将其作为母料与ABS进一步熔融插层制得力学性能良好的ABS/OMMT纳米复合材料,并通过XRD、TGA和TEM等对材料进行了表征.结果表明:制得的PBA/OMMT母料为插层型纳米复合物,OMMT片层间距从2.38nm增大到3.85nm;采用母料法制备ABS/OMMT纳米复合材料,ABS链段易插层进入OMMT层间,使OMMT片层在ABS基体中达到剥离并以纳米尺度均匀分散,较好地保持了ABS的缺口冲击强度.     

Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties

The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.     

Mode I interlaminar fracture behavior and mechanical properties of CFRPs with nanoclay-filled epoxy matrix

The mechanical properties and fracture behavior of nanocomposites and carbon fiber composites (CFRPs) containing organoclay in the epoxy matrix have been investigated. Morphological studies using TEM and XRD revealed that the clay particles within the epoxy resin were intercalated or orderly exfoliated. The organoclay brought about a significant improvement in flexural modulus, especially in the first few wt% of loading, and the improvement of flexural modulus was at the expense of a reduction in flexural strength. The quasi-static fracture toughness increased, whereas the impact fracture toughness dropped sharply with increasing the clay content.Flexural properties of CFRPs containing organoclay modified epoxy matrix generally followed the trend similar to the epoxy nanocomposite although the variation was much smaller for the CFRPs. Both the initiation and propagation values of mode I interlaminar fracture toughness of CFRP composites increased with increasing clay concentration. In particular, the propagation fracture toughness almost doubled with 7 wt% clay loading. A strong correlation was established between the fracture toughness of organoclay-modified epoxy matrix and the CFRP composite interlaminar fracture toughness.     

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。     

Development and characterization of active nanocomposites with embedded shape memory alloy wires

Active nanocomposites of epoxy resin containing bentonite clay and shape memory alloy (SMA) were made to evaluate the thermomechanical behavior in the range of phase transformation of shape memory alloy during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA), crosslinking agent diaminodiphenylsulfone (DDS), purified bentonite organoclay (APOC) and thin Ni‐Ti shape memory alloy wires. The evaluated ratio DGEBA/DDS was 100:40, for the epoxy resin/clay system was 100:1 and the shape memory alloy volumetric fraction of Ni‐Ti wires were 1.55%; 2.56%; 3.57% and 4.54%. The formation of nanocomposite was confirmed by X‐ray diffraction analysis. Phase transformation of the shape memory alloy wires were determined by differential scanning calorimetry (DSC). Specimens of the active nanocomposites were characterized mainly by dynamic mechanical analysis (DMA). According to the DMA results was evidenced a significant increase in glass transition temperature and storage modulus when 1 parts per hundred resin of clay is added to epoxy resin. A recover of storage modulus was observed in the active nanocomposite during heating in the range of the phase transformation of Ni‐Ti shape memory alloy wires when the volumetric fraction is above 3.5%.     

一种促进粘土在环氧树脂中剥离的方法研究

使用对环氧树脂的固化反应有促进作用的有机阳离子对粘土进行有机化处理，得到的有机土与环氧树脂混合后，尽管其层间距较小，层间容纳的环氧树脂较少，但由于催化作用使层间环氧树脂固化较快，结果在环氧的固化过程中粘土更易剥离，从而得到粘土剥离程度较高的环氧树脂／粘土纳米复合材料。这一研究为制备粘土剥离程度更高、性能更好的环氧／粘土纳米复合材料提供了有效的方法。     

Evaluation of the influence of nanoparticles' shapes on the formation of poly(lactic acid) nanocomposites obtained employing the solution method

PLA nanocomposites were prepared by adding organically modified montmorillonite clay (Viscogel B8) and a homoionic clay (NT25), as well as unmodified silica (A200) and modified organic silica (R972). All nanocomposites were obtained by the solution intercalation method using chloroform as a solvent. The materials obtained were essentially characterized by X-ray diffraction and low-field nuclear magnetic resonance relaxometry, through the measurement of proton spin-lattice relaxation time (LF-NMR). Both clays and silicas used to obtain the polymeric nanocomposites showed good dispersion in the polymeric matrix. The relaxation times were distinct for each type of nanoparticle used. The nanocomposite formed with homoionic clay, NT25, presented an increase in the relaxation data, indicating formation of intercalated nanocomposites, contrary to the action of the organoclay Viscogel B8, which preferentially formed an exfoliated nanocomposite. When unmodified and organo-modified silica were added to PLA, an increase in the relaxation time of the polymer matrix was observed. According to the relaxation data, the organosilica R972 dispersed better in the polymeric matrix and consequently interacted better than the A200.     

胺类固化剂-插层剂体系对粘土在环氧树脂中剥离的影响

在对胺类固化剂-插层剂体系分析的基础上,选定叔胺类固化剂(BDMA)-Bronsted酸类插层剂(CH3(CH2)11NH3Cl)体系,制得了环氧树脂/粘土纳米复合材料,复合材料的XRD分析表明粘土在环氧树脂中已经剥离.结合有关研究成果,得出以下结论:在其他条件合适的情况下,只要插层剂为Bronsted酸类或者固化剂为叔胺类,就能得到剥离型的环氧树脂/粘土纳米复合材料.     

Influence of morphology on the dynamic mechanical characteristics of PP-EP/EVA/organoclay nanocomposites

A study on the dynamic mechanical properties of polypropylene copolymer/ethylene–vinyl acetate/organoclay (PP-EP/EVA/C20A) nanocomposites is presented. Nanocomposites were obtained by melt blending. Morphology consisting of intercalated–exfoliated clay nanolayers preferentially located within the EVA phase was observed by transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Polar groups of vinyl acetate in the EVA facilitated the polymer–clay interactions. Changes in the glass transition temperature (T_g) were correlated with changes in the clay intercalation–exfoliation levels. The highly reinforced with intercalated–exfoliated clay layers EVA phase was considered as the origin of the improvement on mechanical properties of the ternary nanocomposites and is associated with the increase on viscosity, heat deflection temperature (HDT), and storage modulus.     

Clay exfoliation and organic modification on wear of nylon 6 nanocomposites processed by different routes

The role of nanoclay on the wear characteristics of nylon 6 nanocomposites processed via different routes is examined in this paper. Pristine clay and organoclay were used in melt-extrusion with the matrix resulting in a largely aggregated and a highly exfoliated morphology, respectively. High exfoliation of pristine clay was also achieved by a water-assist process in melt compounding. Nylon 6/pristine clay composite had the worst wear resistance due to the large aggregated clay particles. For the two nylon 6/exfoliated clay nanocomposites, the one with the organically modified clay outperformed that with the pristine clay exfoliated by water. Detailed study on the wear track and subsurface below of the nylon 6/clay composites using both transmission and scanning electron microscopy provided new insight into the differences in their deformation and damage mechanisms. It was revealed that the interfacial adhesion of clay to matrix, and not the exfoliated morphology of clay, played a critical role in wear. However, exfoliated clay morphology is preferred to aggregate morphology. Hence, the superior wear-performance of nylon 6/organoclay nanocomposite is brought about by a combined effect of fine dispersion of clay platelets in nylon 6, high interfacial interaction between nylon 6 and clay layers, and effective constraint on surrounding nylon 6 material exerted by the clay platelets.