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Sodium Montmorillonite (sodium + montmorillonite)
Selected AbstractsSynthesis of ,-Amino Nitriles from Carbonyl Compounds, Amines, and Trimethylsilyl Cyanide: Comparison between Catalyst-Free Conditions and the Presence of Tin Ion-Exchanged MontmorilloniteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2010Jiacheng Wang Abstract In the absence of catalysts, the three-component, one-pot synthesis of ,-amino nitriles proceeded using various aldehydes and ketones together with amines and trimethylsilyl cyanide (TMSCN) in high yields under neat conditions at room temperature. The addition order of the reagents had a significant influence on the yields of the desired ,-amino nitriles. In contrast, when tin ion-exchanged montmorillonite (Sn-Mont), prepared by the ion-exchange of sodium montmorillonite (Na-Mont) with a tin tetrachloride solution, was used as a catalyst, the reaction rates significantly increased compared with those without catalysts, and the range of the applicable carbonyl compounds was also extended: structurally diverse aromatic, aliphatic and heteroatom-containing carbonyl compounds, including sterically hindered ketones as well as aliphatic and aromatic amines, were converted into the desired ,-amino nitriles in good to excellent yields with short reaction times under mild conditions. Sn-Mont showed a better catalytic activity than proton or other metal ion-exchanged montmorillonites, supported SnO2 catalysts and the previously reported homogeneous or heterogeneous catalysts. The recovered catalyst was reused several times without loss of catalytic performance. Along with the expansion of the interlayer space of Sn-Mont, the strong Brønsted acid and Lewis acid nature of Sn-Mont derived from protons and SnO2 nanoparticles present in the interlayers of Sn-Mont likely played important and cooperative roles in the high catalytic activity. [source] The properties of reactive hot melt polyurethane adhesives modified with novel thermoplastic polyurethanesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009Tae K. Kim Abstract A reactive hot melt adhesive (RHMA) consisting of thermoplastic polyurethane (TPU) was modified with sodium montmorillonite (Na-MMT) intercalated with poly(ethylene glycol) (PEG), and their effects on the adhesion, rheological, and mechanical properties of the RHMA were examined. The Na-MMT intercalated with PEG (Na-MMT/PEG) effectively enhanced the initial bond strength development of the RHMA, although the amounts of Na-MMT/PEG in the RHMA were less than 0.2%. The increase of the complex viscosity and pseudo-solid like behavior observed at low shear rate indicates that there are intimate interactions between the RHMA molecules and Na-MMT/PEG. The improved modulus and tensile strength of the cured RHMA film in the presence of Na-MMT/PEG demonstrates that Na-MMT/PEG effectively reinforced the RHMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Preparation and investigation of ethylene,vinyl acetate copolymer/silicone rubber/clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Shoulin Fang Abstract In this article, the combination of silicone rubber (SR) elastomer with synthetic iron montmorillonite (Fe-MMT) to form a kind of new flame-retardant system based on an ethylene,vinyl acetate (EVA) copolymer is first reported. Also, the flame retardancy of the EVA/SR/Fe-MMT hybrid are compared with that of EVA/SR/natural sodium montmorillonite. The structures of the nanocomposites were characterized with X-ray diffraction and transmission electron microscopy. Cone calorimeter tests and thermogravimetric analysis were used to evaluate the flame-retardant properties and thermal stability of the composites, respectively. In addition, tensile tests were carried out with a universal testing machine, and the morphology of the fracture surface was observed with environmental scanning electron microscopy. We found that SR/organophilic montmorillonite (Fe-OMT) was more effective in reducing the primary peak heat release rate of the nanocomposite, and the EVA/SR/Fe-OMT hybrid had a higher thermal stability in the deacetylated polymer than EVA/SR/sodium organophilic montmorillonite. Moreover, the exfoliated EVA/SR/Fe-OMT nanocomposite displayed excellent mechanical properties because of a better dispersion of Fe-OMT in the polymer matrix, and a possible mechanism is discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Evaluation of polymethacrylic ionomer as compatibilizers for MCPA6/clay compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Tongfei Wu Abstract The compatibilization effects provided by polymethacrylic ionomer (PMMA ionomer) on monomer-casting polyamide6 (MCPA6)/clay (pristine sodium montmorillonite) composites were studied in this work. The PMMA ionomer used in this study was sodium polymethacrylate ionomer (PMMA Na+ -ionomer), which is a copolymer of methyl methacrylate and sodium methacrylate, prepared using emulsion polymerization. MCPA6/clay/PMMA Na+ -ionomer composites were prepared by in situ anionic ring-opening polymerization (AROP) of ,-caprolactam (CLA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) plus rheological measurement were used to characterize those composites. The results indicated that PMMA Na+ -ionomer is a good compatibilizer for this system. With increasing PMMA Na+ -ionomer content, a better dispersion of clay layers was successfully achieved in the MCPA6 matrix. Furthermore, differential scanning calorimetry (DSC) and XRD results indicated that well dispersed silicate layers limit the mobility of the MCPA6 molecule chains to crystallize, reduce the degree crystalline, and favor the formation of the ,-crystalline form of the MCPA6 matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Thermal stability and ablation properties of silicone rubber compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Eung Soo Kim Abstract Effects of incorporation of clay and carbon fiber (CF) into a high temperature vulcanized (HTV) silicone rubber, i.e., poly(dimethylsiloxane) (PDMS) containing vinyl groups, on its thermal stability and ablation properties were explored through thermogravimetric analyses (TGA) and oxy-acetylene torch tests. Natural clay, sodium montmorillonite (MMT), was modified with a silane compound bearing tetra sulfide (TS) groups to prepare MMTS4: the TS groups may react with the vinyl groups of HTV and enhance the interfacial interaction between the clay and HTV. MMTS4 layers were better dispersed than MMT layers in the respective composites with exfoliated/intercalated coexisting morphology. According to TGA results and to the insulation index, the HTV/MMTS4 composite was more thermally stable than HTV/MMT. However, addition of CF to the composites lowered their thermal stability, because of the high thermal conductivity of CF. The time elapsed for the composite specimen, loaded with a constant weight, to break off after the oxy-acetylene flame bursts onto the surface of the specimen was employed as an index for an integrated assessment of the ablation properties, simultaneously taking into consideration the mechanical strength of the char and the rate of decomposition. The elapsed time increased in the order of: HTV < HTV/CF , HTV/MMTS4 < HTV/CF/MMTS4 , HTV/MMT < HTV/CF/MMT. This order was different from the increasing order of the thermal stability determined by TGA results and the insulation index. The decreased degree of crosslinking of the composites with MMTS4 compared with that of the composite with MMT may be unfavorable for the formation of a mechanically strong char and could lead to early rupture of the HTV/MMTS4 specimen. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Rigid PVC/(layered silicate) nanocomposites produced through a novel melt-blending approach,JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2009Laurent M. Matuana On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+ -MMT) and organically modified montmorillonite (Org.-MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X-ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+ -MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.-MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source] Effect of montmorillonite on properties of styrene,butadiene,styrene copolymer modified bitumenPOLYMER ENGINEERING & SCIENCE, Issue 9 2007Jianying Yu 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 [source] Melt processing effects on the structure and mechanical properties of PA-6/clay nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 8 2006Nitin K. Borse Polyamide-6 nanocomposites were prepared using two organoclays, Cloisite 30B and Cloisite 15A, and Cloisite Na+, which is unmodified sodium montmorillonite (Na-MMT) clay. Nanocomposites were prepared using two twin-screw extrusion systems: System B employing conventional mixing and residence time conditions, while System A was modified to achieve longer residence time and higher mixing efficiency. The work considers the effects of mixing conditions, residence time, and interactions between the polymer and clay surface on the structure and mechanical properties of polyamide-6 (PA-6)/clay nanocomposites. Furthermore, a comparison was made between experimental data and the predictions of composite models usually employed to predict mechanical properties of nanocomposites. The melt processing of Cloisite 30B in System A produced the highest degrees of exfoliation and the largest enhancement of mechanical properties. The aspect ratios of the filler particles in the nanocomposites were estimated from TEM micrographs and from composite models. Yield stress data were employed to calculate the values of parameter B in Pukanszky's equation, which incorporates the effects of the interfacial interaction, interfacial strength, and specific surface area of the filler particles. POLYM. ENG. SCI. 46:1094,1103, 2006. © 2006 Society of Plastics Engineers [source] Epoxy nanocomposites curing by microwavesPOLYMER ENGINEERING & SCIENCE, Issue 8 2006Nurseli Uyan In this work, chemically modified sodium montmorillonite and epoxy monomer were used to prepare nanocomposites in two consecutive stages. In the first stage, dodecylamine, octadecylamine, hexadecylamine, and hexadecyltrimethyl ammonium bromide were used to prepare various organophilic clays. In the second stage, the bisphenol-A based epoxy monomer and predetermined amounts of organoclay were mixed together and then cured by an aliphatic polyamine for 20 min under microwave at 400 W. Furthermore, ,-, diacrylate poly(dimethylsiloxane) was added to the mixture before the curing process to modify the toughness of the samples. The mixture was poured into the poly(tetrafluoroethylene) mold; the epoxy resin/curing agent ratio was maintained as 2/1. The clear films formed after microwave irradiation were removed from the mold, cooled, and then stored in a cool and dry medium until characterization. The samples were analyzed by wide angle X-ray diffraction, differential scanning calorimetry, and mechanical tests. Surfaces of the cold fractured samples were also observed under the scanning electron microscope. The results revealed that microwave curing of the samples of 5% organoclay and 5% siloxane showed improvement in mechanical properties. POLYM. ENG. SCI. 46:1104,1110, 2006. © 2006 Society of Plastics Engineers [source] Ethylene propylene diene terpolymer/ethylene vinyl acetate/layered silicate ternary nanocomposite by solution methodPOLYMER ENGINEERING & SCIENCE, Issue 7 2006H. Acharya A new ternary nanocomposite has been developed using ethylene propylene diene terpolymer (EPDM), ethylene vinyl acetate (EVA-45) copolymer, and organically modified layered silicate (16 Me-MMT) from sodium montmorillonite (Na+ -MMT). Wide angle X-ray diffraction and transmission electron microscopic analysis confirmed the intercalation of the polymer chains in between the organosilicate layers and the nanoscale distribution of 16 Me-MMT in polymer matrix, respectively. The measurement of mechanical properties for 2,8 wt% of 16 Me-MMT loadings showed a significant increase in tensile strength, elongation at break, and modulus at different elongations. Such an improvement in mechanical properties has been correlated based on the fracture behavior of nanocomposite by SEM analysis. Thermal stability of EPDM/EVA/layered silicate ternary nanocomposites also showed substantial improvements compared with the neat EPDM/EVA blend, confirming thereby the formation of a high performance nanocomposite. POLYM. ENG. SCI., 46:437,843, 2006. © 2006 Society of Plastics Engineers [source] Influence of clay modification on the reinforcement of vinyl-terminated polydimethylsiloxane networksPOLYMER INTERNATIONAL, Issue 4 2010Eung Soo Kim Abstract A novel method was attempted to reinforce a vinyl-terminated polydimethylsiloxane (PDMS) with two commercially available clays, sodium montmorillonite and Cloisite® 25A. The two clays were functionalized with bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) to prepare Na+MMTS4 and C25AS4, respectively. Incorporation of the tetrasulfide group-containing clays, especially Na+MMTS4, was found to be effective for the enhancement of the interfacial interaction between PDMS and the clays by way of a plausible chemical reaction between the tetrasulfide groups (TSS) and the vinyl-terminated PDMS. Compounding of PDMS with the TESPT-modified clays improved the mechanical properties significantly. In particular, the elongation at break of PDMS/Na+MMTS4 composite was almost twice as high as that of neat PDMS, even if the silicate layers were not fully exfoliated in the PDMS matrix. The tear strength of PDMS was also improved greatly as a result of the incorporation of Na+MMTS4. According to toluene swelling test results, the crosslinking density of the composites was lower than that of neat PDMS, indicating that the improved mechanical properties of the composites arise from enhanced compatibility between the constituents and not from increased crosslinking density. Copyright © 2009 Society of Chemical Industry [source] Synthesis and properties of BCDA-based polyimide,clay nanocompositesPOLYMER INTERNATIONAL, Issue 6 2007P Santhana Gopala Krishnan Abstract Bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA)-based polyimide,clay nanocomposites were prepared from their precursor, namely polyamic acid, by a solution-casting method. The organoclay was prepared by treating sodium montmorillonite (Kunipia F) clay with dodecyltrimethylammonium bromide at 80 °C. Polyamic acid solutions containing various weight percentages of organoclay were prepared from 4,4,-(4,4,-isopropylidenediphenyl-1,1,-diyldioxy)-dianiline and BCDA in N -methyl-2-pyrrolidone containing dispersed particles of organoclay at 20 °C. These solutions were cast on a glass plate using a Doctor's blade and then heated subsequently to obtain nanocomposite films. The nanocomposites were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal mechanical analysis, dynamic mechanical analysis, polarizing microscopy, scanning electron microscopy, transmission electron microscopy, wide-angle X-ray diffraction (WAXD) and thermogravimetric analysis. The glass transition temperature of the nanocomposites was found to be higher than that of pristine polymer. The coefficient of thermal expansion of the nanocomposites decreased with increasing organoclay content. WAXD studies indicated that the extent of silicate layer separation in the nanocomposite films depended upon the organoclay content. Tensile strength and modulus of the nanocomposite containing 1% organoclay were significantly higher when compared to pristine polymer and other nanocomposites. The thermal stability of the nanocomposites was found to be higher than that of pristine polymer in air and nitrogen atmosphere. Copyright © 2007 Society of Chemical Industry [source] Effect of nanoclay on the microcellular structure and morphology of high internal phase emulsion (HIPE) foamsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009M. Serry Ahmed Abstract High internal phase emulsion (HIPE) polymerization foaming process is controlled for the production of novel foams with various microcellular structures and morphologies. In this study, two types of organoclay and one type of natural clay, sodium montmorillonite (NaMMT) were introduced at different concentrations to control the microcellular morphologies, cell sizes and open cell contents. A scanning electron microscopy was used to observe the microcellular morphologies and open cell contents; volume expansion ratio (VER) and cell sizes were evaluated. It was believed that the open cell contents increased as organoclay content increased, due to the lowering of the viscosity ratio of dispersed to continuous phases, as a result of adding nanoclay into the oil phase of emulsion. A correlation between the open cell content and VER that depended on clay content was attempted and the result was quite satisfactory. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||