01793nas a2200217   4500008004100000022001400041245006800055210006700123260007300190300001200263490000700275520104100282653002001323653001701343653002701360653001501387100002501402700002301427700002301450856010201473       2008                        eng d  a0169-131700aSynthesis and characterization of novel organo-montmorillonites0 aSynthesis and characterization of novel organomontmorillonites  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB  a203-2080 v383 a<p>Sodium Montmorillonite (NaMMT) has been modified via cation exchange reaction using three different organic cations. Basal spacings, interlamellar structure and thermal stability of these organo-montmorillonites (OMMT) clays have been characterized using wide angle X-ray diffraction (WARD) and thermogravimetric analysis (TGA) techniques. Increase in the basal spacing due to organic modification is in good agreement with simple theoretical calculations based on van der Waals volume of the cationic ammonium ions. TGA characterization and analysis show that the amount of organic modifier in the OMMT's is in good agreement with theoretically calculated stoichiometric content expected for almost complete exchange of Na+ ions by organic cations. The OMMT's shows stepwise decomposition corresponding to initial weight loss from residual water desorption, followed by decomposition of the organic surfactant and the dehydroxylation of structural water of the montmorillonite layers. (C) 2007 Elsevier B.V. All rights reserved.</p>10aMontmorillonite10aorgano-clays10aorgano-montmorillonite10asurfactant1 aTiwari, Rajkiran, R.1 aKhilar, Kartic, C.1 aNatarajan, Upendra  uhttps://library.ncl.res.in/content/synthesis-and-characterization-novel-organo-montmorillonites-002147nas a2200229   4500008004100000022001400041245013000055210006900185260000800254300001400262490000700276520134400283653001101627653002601638653002001664653001901684653001501703653003001718100002501748700002301773856012101796       2020                        eng d  a0032-388800aCritical organic modifier aliphatic tail length for the formation of poly(methyl methacrylate)-montmorillonite nanocomposites0 aCritical organic modifier aliphatic tail length for the formatio  cJUL  a1604-16170 v603 a<p>In this article, we report the influence of organic modifier structure (alkyl chain length C8-C20, single vs ditallow) and thereby, the effect of hydrophobicity on the structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)-clay hybrids. Melt processed PMMA-clay hybrids were characterized using wide-angle X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The organoclays having an alkyl chain length of more than 12 CH2 groups resulted in the formation of nanocomposites. The glass transition temperature (T-g) of PMMA increased in the presence of clay. The mean-field lattice model was used to predict the free energy for nanocomposite formation, which showed a reasonable match with the experimental results and provided a general guideline for the proper selection of polymer and organoclay (ie, organic modifier) to obtain nanocomposite. Tensile modulus showed maximum improvement of 58% for the nanocomposites compared to 9% improvement for the composites. Tensile modulus increased with increases in the alkyl chain length of the organic modifier and clay loading. The level of improvement for the tensile properties of nanocomposites prepared from primary and secondary ammonium-modified clay is the same as that obtained with the commercial organoclays.</p>
10ahybrid10amechanical properties10aMontmorillonite10aNanocomposites10aorganoclay10apoly(methyl methacrylate)1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra  uhttps://library.ncl.res.in/content/critical-organic-modifier-aliphatic-tail-length-formation-polymethyl-methacrylate