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排序方式: 共有390条查询结果,搜索用时 15 毫秒
1.
T. Peprnicek A. Kalendova J. Simonik J.F. Gerard 《Polymer Degradation and Stability》2006,91(12):3322-3329
The paper concentrates on poly(vinyl chloride) - PVC - from the point of nanocomposite characterisation through thermal degradation of samples, evolution of the changes caused by elevating temperature using TGA, FTIR and Congo Red methods combined with morphological characterisation by XRD and TEM analyses. A novel method of PVC-paste/nanocomposite preparation while processing was used. During preparation, PVC plasticizer was mixed with clay, both natural and organophilic, and the suspension was then compounded with the other components. Two factors were followed: effect of shearing alone, and in combination with temperature. As is presented, the type of nano-filler and its chemical modifier have obvious influence on final properties either thermal or morphological. Presented contribution follows previous part of investigation and brings further information from PVC-paste/nanocomposite field. 相似文献
2.
Cheng-shen Zhu Xin Kang Su-qin He Liu-yang Wang Li-yun Lu College of Materials Engineering Zhengzhou University Zhengzhou China 《高分子科学》2002,(6):551-557
The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods priorto the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), andtermed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were calledmodified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG andWAXD. The results show that interlayer spacings of CTAN and nylon modified MMTs are larger than that of sodium MMTs.Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. Thenanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs dispersehomogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexuralproperties, were also measured and show a tendency to increase with increase of MMT content and reach the maximumvalues at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher thanthat of pure PA 66. 相似文献
3.
蒙脱石修饰碳糊电极测定氨基酸的研究:Ⅱ.酪氨酸的测定 总被引:13,自引:1,他引:13
本文报道蒙脱石修饰碳糊电极测定酪氨酸,在0.001mol/L KCl-HCl(pH=2.0)溶液中开路富集,介质交换后微分脉冲阳极溶出伏安法测定,在0.5-2.5μg/ml范围内有线性,检测限为63ng/ml。可避免其他氨基酸,微量元素和常量金属元素的干扰,直接用于氨基酸药物样品的分析,获得了满意的结果,还对酪氨酸在电极上的反应机理进行了探讨。 相似文献
4.
Takato Mitsudome 《Tetrahedron letters》2006,47(9):1425-1428
Palladium-montmorillonite was proven to be highly efficient for the Wacker oxidation of terminal olefins to the corresponding methyl ketones. The catalyst was reusable while maintaining high activity and selectivity. 相似文献
5.
J.T. Wang 《European Polymer Journal》2005,41(5):1108-1114
Zinc glutarate (ZnGA) synthesized from zinc oxide and glutarate acid was dispersed on the surface of acid-treated montmorillonite (MMT) in quinoline to prepare ZnGA-MMT catalyst. The results of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements indicated that the ZnGA on the surface of acid-treated MMT had the same crystalline structure as pure ZnGA. Copolymerization between CO2 and propylene oxide (PO) was carried out under optimized reaction conditions using ZnGA-MMT catalyst, consequently giving poly(propylene carbonate) (PPC) with high molecular weight in a very high yield (115.2 g polymer per gram of ZnGA). The obtained PPCs were investigated using 13C NMR and FTIR spectra, showing a completely alternating structure. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) examinations showed the PPCs with a high transition temperature of 38 °C and a very high decomposition temperature (>250 °C) due to the presence of MMT residual in polymer. 相似文献
6.
Intercalated nanocomposites constituted of poly(butyl methacrylate) (PBMA) as the matrix and an organically modified montmorillonite as the nanosize filler were prepared and rheologically characterized in detail. The rheological behavior of the composites showed dependence on both temperature and clay content. For composites of low clay contents, the steady shear viscosity showed a Newtonian plateau in the low shear rate region at low temperatures and the plateau was replaced by a shear-thinning curve when the temperature was raised. For composites of higher clay contents, strong shear-thinning behavior were observed at all shear rates and all temperatures. The viscoelastic data of the composites showed unusual terminal behavior of a decreasing terminal slope at low frequencies with increasing temperature and clay loading. X-ray diffraction spectra showed that annealing process at higher temperatures shifted the Bragg reflection peaks to a lower angle and broadened the peaks, which provided the evidence for the existence of a temperature-induced solid-like structure that was responsible for the shear thinning and the unusual terminal viscoelastic behavior. 相似文献
7.
尼龙66/蒙脱土复合材料结晶行为的研究 总被引:8,自引:0,他引:8
在密炼机中采用熔融共混法制备蒙脱土重量分数为 2 5 %、4 5 %的尼龙 6 6 /蒙脱土复合材料 .通过DSC法对非等温结晶行为及在 2 2 8~ 2 4 0℃范围内的等温结晶行为进行研究 ,并与纯尼龙 6 6进行比较 .从其等温和非等温结晶行为的研究表明 ,蒙脱土起成核剂的作用 ,它的填入使尼龙 6 6结晶速率提高 ,但填料与基体间的相互作用使其链段运动困难 ,结晶活化能提高 ;在研究的填料含量变化范围内 ,结晶行为变化不大 ,并且找到该复合材料在 2 2 8~ 2 34℃范围结晶对温度的不敏感区 ;对非等温结晶过程分析 ,刘结平 莫志深方程是适用的 ,而Ozawa方程则是不适用的 . 相似文献
8.
9.
Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites 总被引:1,自引:0,他引:1
Walid H Awad Jeffrey W Gilman Marc Nyden Thomas E Sutto Paul C Trulove Douglas M Fox 《Thermochimica Acta》2004,409(1):3-11
Increasing the thermal stability of organically-modified layered silicates is one of the key points in the successful technical application of polymer-layered silicate nanocomposites on the industrial scale. To circumvent the detrimental effect of the lower thermal stability of alkyl ammonium-treated montmorillonite, a series of alkyl-imidazolium molten salts were prepared and characterized by elemental analysis, thermogravimetry (TGA) and thermal desorption mass spectroscopy (TDMS). The effect of counter ion, alkyl chain length and structural isomerism on the thermal stability of the imidazolium salts was investigated. Alkyl-imidazolium-treated montmorillonite clays were prepared by ion exchange of the imidazolium salts with Na-montmorillonite. These organically-modified clays were characterized by X-ray diffraction (XRD), TDMS and thermogravimetry coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and compared to the conventional quaternary alkyl ammonium montmorillonite. Results indicate that the counter ion has an effect on the thermal stability of the imidazolium salts, and that imidazolium salts with PF6−, N(SO2CF3)2− and BF4− anions are thermally more stable than the halide salts. A relationship was observed between the chain length of the alkyl group and the thermo-oxidative stability; as the chain length increased from propyl, butyl, decyl, hexadecyl, octadecyl to eicosyl, the stability decreased. The results also show that the imidazolium-treated montmorillonite has greater thermal stability compared to the imidazolium halide. Analysis of the decomposition products by FTIR provides an insight about the decomposition products which are water, carbon dioxide and hydrocarbons. 相似文献
10.
In this paper, a new type of organophilic montmorillonites, co-treated by octadecylammonium and aminoundecanoic acid, were synthesized and applied to prepare nylon 66/montmorillonite nanocomposites via melt compounding in a twin extruder. WAXD and TEM characterization indicate that a disordered structure was derived and the montmorillonite platelets dispersed in nanoscale in the nylon 66 matrix. The nanocomposites with co-treated montmorillonite display comparatively higher strength and modulus compared to nylon 66 matrix. 相似文献