熔融插层法制备PET/蒙脱土纳米复合材料及其性能的研究

采用熔融插层法制备PET/蒙脱土纳米复合材料.对制备的PET/蒙脱土纳米复合材料进行表征和研究,通过XRD分析了PET基体中蒙脱土片层的插层情况,发现达到预期效果;试验数据表明:有机蒙脱土使复合材料的拉伸强度和弯曲强度下降,拉伸模量和弯曲模量上升;随着有机蒙脱土含量的增加,复合材料的阻隔性能得到提高.     

一种多功能有机蒙脱土-纳米TiO2/环氧树脂复合材料

将有机蒙脱土（O-MMT）和纳米TiO₂共同复合到环氧树脂中,成功地制备出了一种高性能多功能O-MMT-纳米TiO₂/环氧树脂复合材料。由XRD检测结果和TEM观察结果证实,由于利用了O-MMT、纳米TiO₂与环氧树脂间的相互作用,蒙脱土（MMT）层被高度剥离,所得的二维MMT纳米单片与零维纳米TiO₂颗粒交错分布于树脂基体中。力学性能测试、热分析和耐沾污性试验表明,O-MMT-纳米TiO₂/环氧树脂复合材料的多项性能都比纯环氧树脂有大幅提高。     

酸酐固化环氧树脂-有机蒙脱土纳米复合材料的制备及性能研究

以甲基四氢酸酐为固化剂,对含羟基长链烷基季铵盐改性蒙脱土-环氧树脂纳米复合材料的制备进行了研究。通过TEM、SEM、TGA和DMA等对其微观结构、热性能和动态力学性能等进行表征和分析。TEM结果表明:有机蒙脱土以纳米片层分散在环氧树脂基体中,形成了纳米复合材料;有机蒙脱土含量3wt％时,环氧树脂被同时增韧增强:冲击强度提高87.8%,拉伸强度提高20.9%。纳米片层蒙脱土的加入同时也改善了环氧树脂的热稳定性和动态力学性能;有机蒙脱土含量5wt%时,热分解温度提高24.7℃,热变形温度提高了8.7℃;在T<T_g时,环氧树脂的储能模量提高42.86%,在T>T_g时,提高229.8%;相应玻璃化转变温度T_g提高14.7℃。      

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。     

蒙脱土改性尼龙6性能的研究

采用熔融插层法,通过双螺杆熔融挤出制备尼龙6(PA6)/蒙脱土(MMT)纳米复合材料,测定其拉伸强度和模量、弯曲强度和模量、冲击强度等性能.结果表明,当复合材料中蒙脱土质量分数为2%时得到的PA6/MMT复合材料综合力学性能最佳.     

高度剥离型环氧树脂/蒙脱土纳米复合材料的制备与性能

以丙酮为溶剂,采用超声波分散和高速搅拌混合相结合的方法制备了高度剥离型环氧树脂/蒙脱土纳米复合材料。XRD与TEM测试结果表明,蒙脱土在环氧树脂中得到了高度剥离,大部分蒙脱土被剥离成独立片层,均匀分散于基体树脂中。对材料的力学性能、热机械性能研究表明,蒙脱土能显著提高材料的冲击强度、弹性模量,但降低了材料的拉伸强度与断裂伸长率。蒙脱土使材料的储存模量显著提高,储存模量在材料的橡胶态比在其玻璃态提高的更加明显。     

有机蒙脱土与白炭黑复合填充三元乙丙橡胶性能研究

采用溶液插层法分别制备了含乙烯基的有机蒙脱土(VMMT)和不含乙烯基的有机蒙脱土(OMMT),并通过与三元乙丙橡胶(EPDM)机械共混方法制备了VMMT/EPDM、OMMT/EPDM两种纳米复合材料,对复合材料的力学性能和气体阻隔性能进行了研究。实验发现:当添加相同份数有机蒙脱土时,VMMT/EPDM复合材料的力学性能和气体阻隔性能优于OMMT/EPDM复合材料;当有机蒙脱土添加量为5份时,OMMT/EPDM的拉伸强度提高了60%、100%伸长模量提高了68%,N2透气率降低了29%;当有机蒙脱土添加量为7份时,VMMT/EPDM的拉伸强度提高了99%、100%伸长模量提高了157%、N2透气率降低了52%。结果表明:通过含乙烯基官能团的有机插层剂改性后,有机蒙脱土/EPDM纳米复合材料的力学性能和气体阻隔性能显著提高。     

阻燃聚丙烯/蒙脱土纳米复合材料的制备及性能研究

通过熔融挤出法制备出了膨胀阻燃剂/聚丙烯/有机蒙脱土(IFR/PP/OMMT)阻燃纳米复合材料,XRD分析表明,蒙脱土的层间距扩大,复合材料进入其层闻,形成了纳米复合材料;结果表明,当复合材料中IFR含量为25%时,加入4%的OMMT体系的缺口冲击强度为7.8kJ/m2,拉伸强度为25.3MPa,弯曲模量为1520MPa,极限氧指数(LOI)提高到26,而耐热性也得到提高,复合材料的综合性能最好;通过对膨胀炭层的SEM分析表明,OMMT可以使炭层更加紧密,阻燃性能进一步提高.     

醋酸纤维素/蒙脱土生物纳米复合材料的结构与力学性能

采用熔融插层法在聚乙二醇的增塑作用下制备了醋酸纤维素/蒙脱土(CA/MMT)生物纳米复合材料。利用X射线衍射和透射电镜表征了CA/MMT纳米复合材料的插层结构。X射线衍射结果表明,复合后蒙脱土的层间距增大;透射电镜照片显示,蒙脱土在CA基体中达到纳米级分散,且分散均匀。CA/MMT纳米复合材料的力学性能得到较大提高,加入5 phr有机蒙脱土时,复合材料的拉伸强度从纯增塑CA的38.8 MPa增到48.2 MPa。动态力学测试表明复合材料的储能模量增大,玻璃化转变温度提高。     

微波辅助原位熔融缩聚法制备聚乳酸/有机蒙脱土纳米复合材料

以微波为热源替代传统加热方式,采用原位熔融缩聚法制备出聚乳酸/有机蒙脱土纳米复合材料。有机蒙脱土的加入有利于聚乳酸分子链进入蒙脱土片层,当蒙脱土用量为1.5%时,微波辐射60 min所制得的聚乳酸/有机蒙脱土纳米复合材料与纯聚乳酸相比,拉伸强度提高近2倍,热失重中心温度提高7.3℃,对紫外线的屏蔽波段扩展了50nm以上。透射电镜(TEM)结果表明,有机蒙脱土以剥离态均匀分散于聚乳酸基体中。     

Novel toughened polylactic acid nanocomposite: Mechanical,thermal and morphological properties

The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young’s and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.     

Elastomeric epoxy nanocomposites: Nanostructure and properties

In polymer layered silicate nanocomposites, significant differences have been reported between the effects of the nano-reinforcement on rigid and elastomeric nanocomposites. In this paper, we have studied elastomeric nanocomposites based upon DGEBA epoxy resin filled with montmorillonite (MMT) and cured with a long-chain polyoxypropylene diamine, for comparison with analogous rigid nanocomposites. Ultrasonic mixing was used to disperse the MMT in the matrix to improve homogeneity and decrease the agglomerate size. Two different methods of nanocomposite preparation were used in which the MMT was first swollen with either the curing agent or the epoxy before the addition of, respectively, DGEBA or diamine. A better dispersion of the nanoclay in the matrix and a greater amount of intercalation occurred when the MMT was first swollen with the diamine. The effect of MMT concentrations up to 8 wt.% on the mechanical behaviour of the epoxy/MMT nanocomposites was investigated. It was found that the addition of MMT increased the tensile strength and modulus, although SAXS and TEM indicated that a significant fraction of the clay layers were not exfoliated. Nevertheless, the addition of the clay resulted in changes in the fracture surfaces, as indicated by SEM, consistent with the tensile results and indicative of toughening.     

Novel polyacrylonitrile/Na-MMT/silica nanocomposite: Co-incorporation of two different form nano materials into polymer matrix

Polyacrylonitrile (PAN)/Na-montmorillonite (Na-MMT)/SiO₂ nanocomposites were synthesized via in-situ emulsion polymerization. The X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations show that the Na-MMT layers were exfoliated in polymerization and the nano materials are well dispersed in the polymer matrix. The thermogravimetric analysis (TGA) suggests that co-incorporating Na-MMT and SiO₂ into the polymer matrix significantly enhances the thermal stability of the polymer. At same nano material loading, the PAN/Na-MMT/SiO₂ nanocomposites show superior thermal stability with respect to the PAN/Na-MMT and PAN/SiO₂ nanocomposites. The mechanical properties of the nanocomposites were also examined. It was found that the PAN/Na-MMT/SiO₂ nanocomposites exhibit considerably enhanced moduli compared with the PAN/Na-MMT and PAN/SiO₂ nanocomposites due to the synergistic reinforcing effect.     

Improving the mechanical properties of multiwalled carbon nanotube/epoxy nanocomposites using polymerization in a stirring plasma system

Uniform treatment of multiwalled carbon nanotubes by plasma treatment has been investigated using a custom-built stirring plasma system. A thin plasma polymer with high levels of amine groups has been deposited on MWCNTs using a combination of continuous wave and pulsed plasma polymerization of heptylamine in the stirring plasma system. Scanning electron microscopy showed that the plasma polymerization improved the dispersion and interfacial bonding of the MWCNTs with an epoxy resin at loadings of 0.1, 0.3 and 0.5 wt%. The flexural and thermal mechanical properties of plasma polymerized MWCNT/epoxy nanocomposites were also significantly improved while untreated MWCNT/epoxy nanocomposites showed an opposite trend. The epoxy with 0.5 wt% plasma polymerized MWCNTs had the greatest increase in flexural properties, with the flexural modulus, flexural strength and toughness increasing by about 22%, 17% and 70%, respectively.     

Unsaturated polyester nanocomposites filled with nano alumina

Alumina nanoparticles (60–70 nm) were prepared by the sol–gel technique using citric acid and aluminum nitrate. Casting technique was used to make nanocomposites of unsaturated polyester (UPR) and nano alumina. Transmission Electron Microscopy (TEM) study demonstrated that nano alumina particles were dispersed uniformly in the UPR matrix and agglomeration of particles was found at higher filler loading (>5 wt%). The nanocomposites show higher tensile, flexural and impact strength than pristine UPR. Scanning Electron Microscopy (SEM) of the fractured surface of tensile test samples show that the ductile fracture of UPR was converted to brittle fracture with the addition of nano alumina. Dynamic Mechanical Analysis (DMA) studies showed the storage modulus increased up to 5 wt% loading of nano alumina. The impact strength and storage modulus results agree well. The thermogravimetric studies revealed that the nanocomposites were having higher thermal stability than the pure UPR. As the concentration of the nano alumina in the UP resin increased, the char yield was also increased.     

Thermal, mechanical and vibration characteristics of epoxy-clay nanocomposites

Diglycidyl ether of bisphenol-A (DGEBA) epoxy resin system filled individually with organoclay (OC) and unmodified clay (UC) were synthesized by mechanical shear mixing with the addition of diamino-diphenylmethane (DDM) hardener. The unmodified clay used was Na⁺-Montmorillonite (MMT) and the organoclay was alkyl ammonium treated MMT clay. The reinforcement effect of OC and UC in the epoxy polymer on thermal, mechanical and vibration properties were studied. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) were used to study the structure and morphology of nanocomposites. Curing study shows that the addition of OC in epoxy resin aids the polymerization by catalytic effect, and UC addition does not show any effect in the curing behavior of epoxy polymer. Thermogravimetry analysis (TGA) shows enhanced thermal stability for epoxy with OC fillers than that of epoxy with UC fillers. The epoxy with OC fillers shows considerable improvement on tensile and impact properties over pure epoxy polymer and epoxy with UC fillers. The improvement in tensile and impact properties of nanocomposites is supported with the fracture surface studies. Epoxy with OC fillers shows enhanced vibration characteristics than that of the pure epoxy polymer and epoxy with UC fillers.     

Influence of functionalization on properties of MWCNT-epoxy nanocomposites

The effects of various functionalized multi-walled carbon nanotubes (MWCNTs) on morphological, thermal, and mechanical properties of an epoxy based nanocomposite system were investigated. Chemical functionalization of MWCNT by oxidation (MWCNT-COOH) and direct-fluorination (MWCNT-F) were confirmed by FTIR, Raman spectroscopy, and TGA. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy-based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT-COOH showed 25.5% increase in ultimate flexural strength and 54.8% increase in flexural modulus. A decrease in strength was observed for the MWCNT-F nanocomposites. The premature degradation was attributed to a presumable catalyzation by hydrofluoric acid, HF, which evolved from the MWCNT-F during the curing process. However, only the MWCNT-F nanocomposites showed 22% increase in thermal properties (T_g). All nanophased systems showed increase in storage modulus.     

Reinforcing polymer composites with epoxide-grafted carbon nanotubes

An in situ functionalization method was used to graft epoxide onto single-walled carbon nanotubes (SWNTs) and improve the integration of SWNTs into epoxy polymer. The characterization results of Raman, FT-IR and transmission electron microscopy (TEM) validated the successful functionalization with epoxide. These functionalized SWNTs were used to fabricate nanocomposites, resulting in uniform dispersion and strong interfacial bonding. The mechanical test demonstrated that, with only 1?wt% loading of functionalized SWNTs, the tensile strength of nanocomposites was improved by 40%, and Young's modulus by 60%.These results suggested that efficient load transfer has been achieved through epoxide-grafting. This investigation provided an efficient way to improve the interfacial bonding of multifunctional high-performance nanocomposites for lightweight structure material applications.     

Enhanced ductility and tensile properties of hybrid montmorillonite/cellulose nanowhiskers reinforced polylactic acid nanocomposites

Montmorillonite (MMT)/cellulose nanowhiskers (CNW) reinforced polylactic acid (PLA) hybrid nanocomposites were prepared by solution casting. CNW were isolated from microcrystalline cellulose using a chemical swelling method. An initial study showed that the optimum MMT content, for mechanical properties, in a PLA/MMT nanocomposite is five parts per hundred parts of polymer (phr). Various amounts of CNW were added to the optimum formulation of PLA/MMT to produce PLA/MMT/CNW hybrid nanocomposites. FT-IR analysis indicated the formation of some polar interactions, resulting in enhanced tensile properties of the hybrid nanocomposites. The highest tensile strength for the hybrid nanocomposites was obtained for a 1 phr CNW content. Young’s modulus was also found to increase with an increasing CNW content. Interestingly, the strain to failure (or ductility) of the hybrid nanocomposites increased significantly from ~10 to ~90 % with the addition of 1 phr CNW. This increase in ductility was proposed to be due to the nucleation of crazes and the formation of shear bands in the PLA.