PS/MMT复合材料的结构与燃烧性能

将聚苯乙烯(PS)树脂与不同种类蒙脱土(MMT)进行熔融复合制备PS/MMT复合材料,通过X射线衍射(XRD)和高分辨透射电子显微镜(TEM)对复合材料的结构进行分析,采用氧指数法和锥形量热法研究复合材料的燃烧性能.结果表明:用有机蒙脱土(OMMT)制备的PS/OMMT复合材料,是一种插层型复合材料,而用蒙脱土原土(N...     

聚乳酸/蒙脱土纳米复合材料研究进展

分析了聚乳酸(PLA)/蒙脱土(MMT)纳米复合材料的结构,介绍了溶液插层复合法、原位插层复合法、熔融插层复合法等PLA/MMT纳米复合材料的制备方法,从力学性能、热稳定性能、降解性能、气体阻隔性能等方面阐述了PLA/MMT纳米复合材料的性能,并对PLA/MMT纳米复合材料的发展前景进行了展望。     

蒙脱土改性酚醛树脂复合材料的制备与性能研究

为提高酚醛树脂(PF)的热稳定性,利用原位插层法制备了PF/蒙脱土(MMT)、PF/有机化蒙脱土(OMMT)纳米复合材料,并比较了PF、PF/OMMT或PF/MMT经高温热处理后的力学性能和导电性能.研究表明,与PF复合后,OMMT和MMT都形成了剥离型的片层结构.与PF/OMMT复合材料相比,PF/MMT的质量保持率...     

HIPS/蒙脱土复合材料炭层结构对阻燃性能的影响

采用熔融插层法制备了不同有机蒙脱土(OMMT)及无机蒙脱土(MMT)含量的HIPS/OMMT和HIPS/MMT复合材料,并通过锥形量热仪评价了复合材料的阻燃性能;采用数码相机、扫描电镜(SEM)观察了燃烧残余物结构。结果表明,OMMT的加入显著提高了HIPS/OMMT复合材料阻燃性,而MMT的加入,HIPS/MMT复合材料的阻燃性能提高不明显。HIPS/OMMT复合材料燃烧结束形成了皮层-蜂窝层复合的炭渣结构,对其阻燃性有重要的影响。     

右旋布洛芬/蒙脱土复合物的制备及体外释放性能研究

目的:以天然蒙脱土作为药物载体,制备右旋布洛芬/蒙脱土复合物,并对其进行结构表征和体外释药考察.方法:采用溶液插层法制备右旋布洛芬/蒙脱土复合物(S(+)-ibuprofen/montmorillonite,S(+)-IBU/MMT).通过X-射线衍射(XRD)和傅里叶红外变换光谱(FT-IR)对复合物的结构进行表征;采用透析法研究介质的pH值对S(+)-IBU/MMT体外释放的影响.结果蒙脱土层间距由1.25 nm增大到1.31 nm,右旋布洛芬以插层方式进入蒙脱土的层间域;S(+)-IBU/MMT复合物体外释药受释放介质pH值的影响,在pH 1.0、pH4.5和pH 6.8的释放介质中,右旋布洛芬12 h的累积释放百分量分别18％、36％和88％.结论采用溶液插层法所制备S(+)-IBU/MMT复合物具有较好的缓释作用.     

聚甲基丙烯酸/蒙脱土纳米复合材料的制备及性能

用甲基丙烯酸(methacrylic acid,MAA)在钠基蒙脱土(montmorillonite,MMT)层间直接原位插层聚合制备了聚甲基丙烯酸/蒙脱土(polymethacrylic acid/montmorillonite,PMAA/MMT)纳米复合材料.以蒙脱土的层间距、插层进入蒙脱土层间的聚合物含量及应用于皮革鞣制的实验结果为考察指标,对制备过程中的引发剂用量及蒙脱土用量进行了单因素实验研究.结果表明:所制备的PMAA/MMT纳米复合材料属于剥离型纳米复合材料,应用于皮革鞣制所得坯革的增厚率及湿热稳定性均有较大提高.     

聚丙烯/蒙脱土纳米复合材料的结构及物理性能研究

采用化学反应法制备了Ziegler-Natta/有机改性蒙脱土复合催化剂,并通过丙烯单体原位插层聚合法制备出聚丙烯/蒙脱土(PP/MMT)纳米复合材料,研究了复合材料的微观结构、热性能以及加工稳定性等。结果表明,原位聚合法制备的复合材料为剥离型纳米复合材料,其中MMT片层以纳米尺寸均匀分散在PP基体中,MMT平均厚度小于10nm;随MMT含量的提高,复合材料的热稳定性提高;原位聚合制备的PP/MMT纳米复合材料在长时间剪切过程中部分MMT会发生自聚集,控制剪切时间可以有效防止MMT的自聚集;原位聚合制备的PP/MMT复合材料(粉料)中,PP以α晶型为主,纳米MMT的引入并不会诱导生成聚丙烯β晶型,复合材料中β晶型的出现与退火条件有关。     

聚乙烯/纳米蒙脱土复合材料的非等温结晶行为

原位聚合法制备了不同蒙脱土含量的聚乙烯(PE)/纳米蒙脱土(MMT)复合材料.用透射电镜分析了MMT在PE基体中的分散情况,结果表明:随着MMT含量的增加,复合材料的结构从剥离型转变为剥离型和插层型混合结构.用DSC分析了PE/纳米MMT复合材料的非等温结晶行为,结果表明:复合材料的非等温结晶行为符合Avramin方程,随着MMT含量的增加,Avramin方程指数(n)减小,结晶时间(t1/2)增加.     

乳液插层法制备丁苯橡胶/天然橡胶/蒙脱土纳米复合材料的研究

采用乳液插层法制备了丁苯橡胶/天然橡胶/蒙脱土（SBR/NR/MMT）纳米复合材料。采用透射电子显微镜研究了复合材料的亚微观形态,并对复合材料的性能进行了研究。透射电镜结果显示,制备出了插层型的SBR/NR/MMT复合材料。当蒙脱土含量较低时,SBR/NR/MMT纳米复合材料的力学性能随蒙脱土用量的增加而增大。SBR/NR/MMT复合材料的耐油性能随蒙脱土含量的增加而提高。蒙脱土的加入对纳米复合材料的耐磨性能没有太大影响。     

蒙脱土填充环氧化天然橡胶/PVC热塑性弹性体的制备与性能研究

采用熔融插层法制备蒙脱土(MMT)/聚氯乙烯(PVC)插层产物,再将该产物与环氧化天然橡胶(ENR)在密炼机中进行动态硫化制备ENR/PVC/MMT共混型热塑性弹性体(TPE),研究了蒙脱土的填充量对共混物力学性能、热稳定性以及动态机械性能的影响。实验结果表明:随着蒙脱土填充量的增加,ENR/PVC/MMT共混型热塑性弹性体的拉伸强度、撕裂强度和邵氏硬度增大,断裂伸长率略有下降;蒙脱土会促进TPV中PVC的降解,使得复合材料的热稳定性降低,动态热机械分析测得的复合材料的tanδ曲线峰峰强降低,峰宽变宽。     

A New Type of Dispersant [Sodium Salt of Styrene–Methacrylic Acid Copolymer (SSMA)/Montmorillonite (MMT) Nanocomposite] for Pesticide Water Dispersible Granules

A new type of dispersant [sodium salt of styrene–methacrylic acid copolymer (SSMA)/montmorillonite (MMT) nanocomposite] with different content of the MMT was synthesized through in situ solution free radical copolymerization. X‐ray diffraction measurements and electron microscopy observations prove that SSMA molecules can enter the interlayer space of MMT and form an intercalated structure. There are both fully intercalated and partly intercalated structures in the nanocomposites, which are related to the loading content of MMT. Transmission and scanning electron microscopy images indicate that the exfoliation degree of MMT in the nanocomposites decrease with increasing MMT content. Infrared spectroscopy (FTIR) analysis shows that there are hydrogen‐bonding interactions between carboxyl groups of SSMA and hydroxyl groups of MMT. Atrazine water dispersible granules were prepared by using SSMA/MMT nanocomposite as dispersant and their suspensibility in aqueous solution was determined to evaluate the dispersion properties of the nanocomposite. The results show that the addition of MMT can not only increase the steric effect of the SSMA to improve its dispersion properties, but also reduce the production cost of SSMA. The optimum loading content of MMT is 10 wt%.     

Effect of montmorillonite on properties of styrene–butadiene–styrene copolymer modified bitumen

Clay/styrene–butadiene–styrene (SBS) modified bitumen composites were prepared by melt blending with different contents of sodium montmorillonite (Na‐MMT) and organophilic montmorillonite (OMMT). The structures of clay/SBS modified bitumen composites were characterized by XRD. The XRD results showed that Na‐MMT/SBS modified bitumen composites may form an intercalated structure, whereas the OMMT/SBS modified bitumen composites may form an exfoliated structure. Effects of MMT on physical properties, dynamic rheological behaviors, and aging properties of SBS modified bitumen were investigated. The addition of Na‐MMT and OMMT increases both the softening point and viscosity of SBS modified bitumens and the clay/SBS modified bitumens exhibited higher complex modulus, lower phase angle. The high‐temperature storage stability can also be improved by clay with a proper amount added. Furthermore, clay/SBS modified bitumen composites showed better resistance to aging than SBS modified bitumen, which was ascribed to barrier of the intercalated or exfoliated structure to oxygen, reducing efficiently the oxidation of bitumen, and the degradation of SBS. POLYM. ENG. SCI., 47:1289–1295, 2007. © 2007 Society of Plastics Engineers     

叶片挤出机制备PLA/MMT复合材料性能的研究

利用以拉伸形变为主导的叶片挤出机制备了不同质量比的聚乳酸/蒙脱土(PLA/MMT)纳米复合材料,通过透射电子显微镜(TEM)和X射线衍射仪(XRD)表征了该复合材料的微观结构及形貌,并探讨了不同含量的MMT对PLA/MMT复合材料的力学性能以及动态力学性能的影响。结果表明:PLA分子链插入MMT片层之间,形成了具有插层结构的PLA/MMT纳米复合材料;该复合材料的拉伸强度、拉伸模量及冲击强度均随着MMT含量的增加呈先增后减的趋势;当MMT含量为2.5%时,复合材料的综合力学性能达到最佳,其中拉伸模量比纯PLA提高了170%,冲击强度则提高了130%,说明少量MMT的加入对PLA能起到增强增韧的作用。另外,动态力学性能测试结果表明,随着MMT含量的增加,复合材料的玻璃化转变温度有下降的趋势。     

表面活性剂和硅烷偶联剂有机复合改性蒙脱土的制备及性能表征

为增加蒙脱土与有机物的相容性,采用十六烷基三甲基溴化铵(CTAB)与硅烷偶联剂(KH-560)对蒙脱土进行了有机复合改性。X-射线衍射和红外光谱的结果表明,CTAB已插入蒙脱土片层,平均层间距离从1.54 nm增大到3.98 nm和2.08 nm,而KH-560未插入蒙脱土片层,只是覆盖在蒙脱土表面,未改变蒙脱土的插层结构;分散性实验表明,表面活性剂和硅烷偶联剂有机复合改性的蒙脱土在苯乙烯、液体石蜡中的分散性好于其他改性蒙脱土;有机复合改性不仅增大了蒙脱土层间距,且改善了蒙脱土与聚氯乙烯的界面效果,提高了蒙脱土在聚氯乙烯基体中的分散均匀性,从而使聚氯乙烯/蒙脱土复合材料玻璃化转变温度的提高和力学性能的改善更明显。     

Combining In‐Situ Organic Modification of Montmorillonite and the Latex Compounding Method to Prepare High‐Performance Rubber‐Montmorillonite Nanocomposites

Summary: To improve the interfacial interaction in MMT‐SBR nanocomposites, one type of UOAC was introduced to in‐situ modified MMT before latex compounding with SBR. The influence of the UOAC/MMT ratio on the structure and properties of MMT/SBR nanocomposites were carefully studied by XRD, TEM, and mechanical testing. It was found that through the in‐situ organic modification, a rubber‐intercalated structure of MMT was obtained in the nanocomposites, and the amount of rubber‐intercalated structure strongly depended on the UOAC/MMT ratio. The tensile strength of MMT‐SBR nanocomposites was enhanced dramatically from 4 to 18 MPa by in‐situ organic modification of MMT.

Stress‐strain diagram of SBR/clay nanocomposites.     

Isothermal crystallization of intercalated and exfoliated polyethylene/montmorillonite nanocomposites prepared by in situ polymerization

Polyethylene/montmorillonite (PE/MMT) nanocomposites with different dispersion states of MMT were prepared by in situ polymerization. Isothermal crystallization of the intercalated nanocomposite, in which the PE chains were confined in the MMT layers, was studied and was compared with that of the exfoliated nanocomposite. It is observed that the intercalated sample has longer induction period, longer crystallization half time and larger crystallization activation energy than the exfoliated sample, showing that crystallization of PE is retarded due to confinement of the MMT layers. Analysis of crystallization kinetics shows that Avrami exponent (n) increases gradually with crystallization temperature. However, the maximal value of n is 2.0 for the intercalated sample, but it can reach 3.0 for the exfoliated sample. It is inferred that the stems of the PE crystals confined in the MMT layers are parallel to the MMT layers. The Hoffman-Weeks extrapolation method cannot be applied in the intercalated sample because of the small lateral surface of the PE crystals. Based on the depression of the melting temperature, the specific free energy of the PE/MMT interface was estimated, which is about 1.0 mJ/cm², much smaller than the free energy of the lateral surface of PE crystals. This is attributed to the origin of the strong nucleation effect of MMT.     

Development of polyvinyl alcohol/intercalated MMT composite foams fabricated by melt extrusion

In this work, novel polyvinyl alcohol (PVA)/intercalated montmorillonite (MMT) nanocomposite foams were fabricated by melt extrusion with fixed amount of foaming agent, and the structure and properties were investigated with X‐ray diffraction, transmittance electron microscope, differential scanning calorimetry, plate rheometer, scanning electron microscope, density analysis, and mechanical testing in detail. The results revealed that pristine MMT could be intercalated by PVA during melt‐extrusion. Both exfoliation and intercalation structure was formed in the composites. The strong interaction between PVA and MMT restricted the motion of PVA molecules, leading to the enhanced complex viscosity, storage modulus, and melt flow index, suggesting the improved melt elasticity and melt strength. The improved melt strength of PVA through MMT incorporation facilitated the foaming process. With the increase of MMT, cell rupture was limited and the thickness of cell‐wall decreased, leading to the decreased density. The homogeneous cells and the closed cell structure with the foaming density of 0.35 g/cm³ could be formed with 2 wt % MMT incorporation. With the increase of MMT, the tensile strength of PVA/MMT foams decreased because of the enlarged foaming ratio and decreased density. This work aims to pave a simple and convenient way to produce biodegradable foams. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42706.     

Synthesis of Na+‐montmorillonite/amphiphilic polyurethane nanocomposite via bulk and coalescence emulsion polymerization

Polyurethane/clay nanocomposites have been synthesized using Na⁺‐montmorillonite (Na⁺‐MMT)/amphiphilic urethane precursor (APU) chains that have hydrophilic polyethylene oxide (PEO) chains and hydrophobic segments at the same molecules. Nanocomposites were synthesized through two different crosslinking polymerization methods. One is UV curing of melt mixed APU/Na⁺‐MMT mixtures; the other is coalescence polymerization of APU/Na⁺‐MMT emulsions. These two kinds of composites had intercalated silicate layers of Na⁺‐montmorillonite by insertion of PEO chains in APU chains, which was confirmed by X‐ray diffraction measurement and transmission electron microscopy. These composite films also showed improved mechanical properties compared to pristine APU films. Although the two kinds of nanocomposites exhibited the same degree of intercalation and were synthesized based on the same precursor chains, these nanocomposite films had the different mechanical properties. Nanocomposites synthesized using APU/Na⁺‐MMT emulsions, having microphase‐separated structure, had greater tensile strength than those prepared with melt‐mixed APU/Na⁺‐MMT mixtures. Location of intercalated Na⁺‐MMT by PEO chains at the oil–water interface also could be confirmed by rheological behavior of the APU/Na⁺‐MMT/water mixture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3130–3136, 2003