共查询到20条相似文献,搜索用时 15 毫秒
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将有机化的蒙脱土与尼龙6(PA6)在Haake共混机中共混,制备出尼龙6/蒙脱土纳米复合材料(PA6N);对尼龙6/蒙脱土纳米复合材料和纯尼龙6分别进行差示扫描量热法非等温结晶试验,以了解蒙脱土在尼龙6/蒙脱土纳米复合材料中的成核作用、扩大尼龙6在包装领域的应用范围.与此同时,采用偏光显微镜测定了样品的结晶形态;采用紫... 相似文献
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E. M. Araújo Renata Barbosa Amanda D. Oliveira Crislene R. S. Morais T. J. A. deMélo A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2007,87(3):811-814
Polyethylene/montmorillonite clay nanocomposites were obtained via direct
melt intercalation. The clay was organically modified with four different
types of quaternary ammonium salts. The objective of this work is to study
the use of montmorillonite clay in the production of nanocomposites by means
on rheological, mechanical and crystallization properties of nanocomposites
and to compare to the properties of the matrix and PE/unmodified clay nanocomposites.
In general, the tensile test showed that the yield strength and modulus of
the nanocomposites are close to the pure PE. Apparently, the mixture with
Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay. 相似文献
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Chen‐Rui Tseng Hsin‐Yi Lee Feng‐Chih Chang 《Journal of Polymer Science.Polymer Physics》2001,39(17):2097-2107
We investigated the effects of montmorillonite (clay) on the crystallization kinetics of syndiotactic polystyrene (sPS) with isothermal differential scanning calorimetry analyses. The clay was dispersed into the sPS matrix via melt blending on a scale of 1–2 nm or up to about 100 nm, depending on the surfactant treatment. For a crystallization temperature of 240 °C, the isothermal crystallization data were fitted well with the Avrami crystallization equation. Crystallization data on the kinetic parameters (i.e., the crystallization rate constant, Avrami exponent, clay content, and clay/surfactant cation‐exchange ratio) were also investigated. Experimental results indicated that the crystallization rate constant of the sPS nanocomposite increased with increasing clay content. The clay played a vital role in facilitating the formation on the thermodynamically more favorable all‐β‐form crystal when the sPS was melt‐crystallized. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2097–2107, 2001 相似文献
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Z. M. Wang T. C. Chung J. W. Gilman E. Manias 《Journal of polymer science. Part A, Polymer chemistry》2003,41(24):3173-3187
Monoalkyl- and dialkyl-imidazolium surfactants were used to prepare organically modified montmorillonites with markedly improved thermal stability in comparison with their alkyl-ammonium equivalents (the decomposition temperatures increased by ca. 100 °C). Such an increase in the thermal stability affords the opportunity to form syndiotactic polystyrene (s-PS)/imidazolium-montmorillonite nanocomposites even under static melt-intercalation conditions in the absence of high shear rates or solvents. Upon nanocomposite formation, s-PS exhibited an improvement in the thermal stability in comparison with neat s-PS, and the β-crystal form of s-PS became dominant. This crystallization response agrees with previous studies of s-PS/pyridinium-montmorillonite hybrids and is tentatively attributed to a heterogeneous nucleation action by the inorganic fillers. © 2003 Wiley Periodicals, Inc.* J Polym Sci Part B: Polym Phys 41: 3173–3187, 2003 相似文献
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Preparation and nonisothermal crystallization behavior of polyamide 6/montmorillonite nanocomposites
Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X‐ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in γ‐crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami‐Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2878–2891, 2004 相似文献
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L. Minkova 《Colloid and polymer science》1994,272(2):115-120
The non-isothermal crystallization of UHMWPE, filled with different inorganic fillers during the polymerization on the catalyst system TiCl4/(C2H5)2AlCl/(C6H5)2Mg has been studied by DSC and polarization microscopy. The melting conditions of UHMWPE have been established before the crystallization experiments. It is shown that the fillers act as nucleating agents only when the crystallization is carried out from a melt, obtained at temperature above the flow temperature of UHMWPE, and at slow cooling rate. It was established that the efficiency of nucleation passes through maximum at 50 wt.% of the filler. It is assumed that this is due to the reduction of the heterogeneous sites, because of the aggregation of the filler with high concentration. The non-isothermal crystallization kinetics is studied by Harnisch and Muschik method. The Avrami exponents do not change in the presence of a filler with concentration up to 90 wt.%. 相似文献
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F. Román S. Montserrat J. M. Hutchinson 《Journal of Thermal Analysis and Calorimetry》2007,87(1):113-118
The procedure for
the fabrication of epoxy-based polymer layered silicate nanocomposites is
important in respect of the nanostructure that is developed. To further our
understanding of this, the influence of an organically modified clay (montmorillonite,
MMT) on the curing kinetics of an epoxy resin has been studied by differential
scanning calorimetry. Clay loadings of 10 and 20 mass% are used, and isothermal
as well as dynamic cures have been investigated. For both cure schedules the
effect of the MMT is to advance the reaction. Kinetic analysis yields values
for the activation energy, but shows that the reaction cannot be described
simply by the usual autocatalytic equation. The glass transition of the cured
nanocomposites is lower than that for the cured neat resin, a result that
is attributed to homopolymerisation taking place in addition to the epoxy–amine
reaction. 相似文献
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The melt-direct intercalation method was employed to prepare polypropylene (PP)/maleic anhydride grafted polypropylene (PP-g-MAH)/organic-montmorillonite (Org-MMT), X-ray diffractometer was used to investigate the intercalation effect and crystallite size in composites and TEM micrograph to observe the dispersion of Org-MMT interlayers in polypropylene. The results showed that by introducing maleated polypropylene in PP/Org-MMT composite, macromolecule segments had intercalated into interlayer space of Org-MMT. As a result, Org-MMT interlayers were dispersed evenly in polypropylene and PP/PP-g-MAH/Org-MMT nanocomposite was synthesized. The crystallite size of nanocomposite perpendicular to the crystalline plane such as (0 4 0), (1 3 0), (1 1 1), (0 4 1) is smaller than that of pristine PP, which indicated that the crystallite size of PP in nanocomposite can be diminished by adding PP-g-MAH and Org-MMT in PP. Moreover, the nonisothermal crystallization kinetics of PP and PP/PP-g-MAH/Org-MMT nanocomposite was investigated by differential scanning calorimetry (DSC) with various cooling rates. The Avrami analysis modified by Jeziorny, Ozawa method and a method developed by Liu were employed to describe the nonisothermal crystallization process of these samples. The difference in the exponent n between PP and nanocomposite, indicated that nonisothermal kinetic crystallization corresponded to tridimensional growth with heterogeneous nucleation. The values of half-time, Zc, F(T) and K(T) showed that the crystallization rate of composites was faster than that of PP at a given cooling rate. 相似文献
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Ji Hye Hong Eun Hwan Jeong Han Sup Lee Du Hyun Baik Seung Won Seo Ji Ho Youk 《Journal of Polymer Science.Polymer Physics》2005,43(22):3171-3177
Polyurethane/organically modified montmorillonite (PU/O‐MMT) nanocomposites were electrospun and the effect of O‐MMT on the morphology and physical properties of the PU/O‐MMT nanofiber mats were investigated for the first time. The average diameters of the PU/O‐MMT nanofibers were ranged from 150 to 410 nm. The conductivities of the PU/O‐MMT solutions were linearly increased with increasing the content of O‐MMT, which caused a decrease in the average diameters of the PU/O‐MMT nanofibers. The as‐electrospun PU and PU/O‐MMT nanofibers were not microphase separated. The exfoliated MMT layers were well distributed within the PU/O‐MMT nanofibers and oriented along the fiber axis. When the PU/O‐MMT nanofibers were annealed, the exfoliated MMT layers hindered the microphase separation of the PU. The electrospinning of PU/O‐MMT nanocomposites resulted in PU nanofiber mats with improved Young's modulus and tensile strength. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3171–3177, 2005 相似文献
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Xu W. B. Zhou Z. F. Ge M. L. Pan W.-P. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):91-99
Polyvinyl chloride (PVC)/organic-montmorillonite composites were prepared by melt intercalation. Their structures and properties
were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and mechanical testing. The results
showed that PVC chains could be intercalated into the gallery of organically modified montmorillonite to form exfoliated PVC/organic-montmorillonite
nanocomposites, and the glass transition temperatures of PVC/organic-montmorillonite composites were lower than that of neat
PVC. However, the tensile strength, and both the Izod type and Charpy notched impact strengths of PVC/organic-montmorillonite
nanocomposites were fitted with the linear expressions: t=535.07-6.39T
g, s
I=378.76-4.59T
g and sC=276.29-3.59T
g, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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采用差示扫描量热法DSC研究了水性聚氨酯/功能化石墨烯(WPU/FGNs)纳米复合材料的非等温结晶行为,分别采用Ozawa方程、莫志深方程研究复合材料的非等温结晶动力学,并通过Kissinger方程计算了结晶过程中的活化能。 结果表明,石墨烯在复合材料的结晶过程中起到异相成核剂的作用,提高了复合材料的结晶起始温度、峰值温度和结晶速率;增加石墨烯的质量分数,复合材料的结晶维数增加;石墨烯增加至0.3%,复合材料的活化能从-47.74 kJ/mol降低至-53.60 kJ/mol,继续增加石墨烯至1.0%,复合材料的活化能增加至-41.74 kJ/mol。 相似文献
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E. M. Araújo Renata Barbosa Crislene R. S. Morais L. E. B. Soledade A. G. Souza Moema Q. Vieira 《Journal of Thermal Analysis and Calorimetry》2007,90(3):841-848
Nanocomposites containing both polyethylene and montmorillonite clay organically modified with four different types of quaternary
ammonium salts were obtained via direct melt intercalation. Thus, the main purpose of this work was to evaluate the effect
of the organoclay on the thermal stability of polyethylene. The organoclays were characterized by XRD, FTIR, DSC and TG. The
polyethylene/organoclay nanocomposites were studied by XRD, TEM, TG, besides an evaluation of their mechanical properties.
The results showed that the salts were incorporated by intercalation between the layers of the organoclay and, apparently
that the nanocomposites were more thermally stable than pure polyethylene. 相似文献
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Qing‐Xin Zhang Zhong‐Zhen Yu Mingshu Yang Jun Ma Yiu‐Wing Mai 《Journal of Polymer Science.Polymer Physics》2003,41(22):2861-2869
Nylon‐66 nanocomposites were prepared by melt‐compounding nylon‐66 with organically modified montmorillonite (MMT). The organic MMT layers were exfoliated in a nylon‐66 matrix as confirmed by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy. The presence of MMT layers increased the crystallization temperature of nylon‐66 because of the heterogeneous nucleation of MMT. Multiple melting behavior was observed in the nylon‐66/MMT nanocomposites, and the MMT layers induced the formation of form II spherulites of nylon‐66. The crystallite sizes L100 and L010 of nylon‐66, determined by WAXD, decreased with an increasing MMT content. High‐temperature WAXD was performed to determine the Brill transition in the nylon‐66/MMT nanocomposites. Polarized optical microscopy demonstrated that the dimension of nylon‐66 spherulites decreased because of the effect of the MMT layers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2861–2869, 2003 相似文献
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C. J. Pérez V. A. Alvarez P. M. Stefani A. Vázquez 《Journal of Thermal Analysis and Calorimetry》2007,88(3):825-832
Non-isothermal crystallization of MaterBi-Z (starch-polycaprolactone blend) and its nanocomposites with different clay contents
(0, 2.5 and 5 mass%) was studied. The experimental data show that clay can be act both as nucleating or retarding agent depend
on the clay content.
Kinetic parameters obtained by using a non-linear regression method, i.e., Kamal’s model and Dietz’s modification, were able
to describe the non-isothermal crystallization behavior of the studied materials. A full model that takes into account the
induction and growth of the crystal during cooling under non-isothermal conditions was used to obtain a continuous cooling
transformation diagrams. 相似文献
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LIU Xuening HU Nan ZHANG Hongtao HA Chengyong & YANG Zhizhong Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou China 《中国科学B辑(英文版)》2005,48(4):326-333
Polymer-clay nanocomposites are a class of hybrid materials composed of organic polymer matrix in which layered inorganic particles with nano-scale di- mension are distributed with self-assembled pattern uniformly. These nanocomposites synergistically int… 相似文献
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Huaili Qin Zhenguang Zhang Meng Feng Fangling Gong Shimin Zhang Mingshu Yang 《Journal of Polymer Science.Polymer Physics》2004,42(16):3006-3012
The photo‐oxidative degradation of polyethylene/montmorillonite (PE/MMT) nanocomposite and microcomposite has been investigated. It has been found that the rate of photo‐oxidative degradation of PE/MMT nanocomposite and PE/Mn+MMT (where Mn+ stands for multivalent transition metal cation) microcomposites is much faster than that of pure PE. For the PE/MMT nanocomposite, the acceleration of photo‐oxidative degradation is due to the influence of MMT and ammonium ion, in which the influence of ammonium is primary. The decomposition of ammonium ion may create acidic sites on layered silicates; meanwhile, the complex crystallographic structure and habit of clay minerals could also result in some active sites. The reversible photo‐redox reaction of transition metal cations has a catalytic effect in the degradation of the polymer matrix. All these catalytic active sites can accept single electrons from donor molecules of polymer matrix and induce the formation of free radical upon UV irradiation. The generation of free radical leads to the oxidization and break of molecular chain. Thus, the materials suffer degradation and their mechanical strength decreases. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3006–3012, 2004 相似文献
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