00720nas a2200145 4500008004100000022001400041245018000055210006900235260007900304300001300383490000800396100002300404700001700427856013000444 2006 eng d a0065-772700aMicellization and colloidal adsorption of a model polyelectrolyte diblock copolymer in selective solvent: theoretical model combining scaling and lattice mean field approaches0 aMicellization and colloidal adsorption of a model polyelectrolyt a1155 16th ST, NW, Washington, DC 20036 USAbAmerican Chemical SocietycMAR a358-COLL0 v2311 aNatarajan, Upendra1 aPoddar, Neha uhttps://library.ncl.res.in/content/micellization-and-colloidal-adsorption-model-polyelectrolyte-diblock-copolymer-selective-000719nas a2200145 4500008004100000022001400041245017300055210006900228260007900297300001300376490000800389100002300397700002500420856012800445 2006 eng d a0065-772700aPreparation and characterization of a series of new organically modified montmorillonite clays using X-ray diffraction, thermogravimetric analysis and FTIR spectroscopy0 aPreparation and characterization of a series of new organically  a1155 16th ST, NW, Washington, DC 20036 USAbAmerican Chemical SocietycMAR a211-COLL0 v2311 aNatarajan, Upendra1 aTiwari, Rajkiran, R. uhttps://library.ncl.res.in/content/preparation-and-characterization-series-new-organically-modified-montmorillonite-clays-002226nas a2200217 4500008004100000022001400041245014600055210006900201260006800270300001400338490000800352520138100360653002601741653001901767653001501786653001401801653002301815100002501838700002301863856012201886 2007 eng d a0021-899500aInfluence of organic modification on mechanical properties of melt processed intercalated poly(methyl methacrylate)-organoclay nanocomposites0 aInfluence of organic modification on mechanical properties of me a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcSEP a2433-24430 v1053 a

The influence of organic modifiers on intercalation extent, structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Two different organic modifiers with varying hydrophobicity (single tallow versus ditallow) were investigated. The nanocomposites were prepared from melt processing method and characterized using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. Mechanical properties such as tensile modulus (E), break stress (sigma(brk)), and 0% break strain (epsilon(brk)) were determined for nanocomposites at various clay loadings. Extent of PMMA intercalation is sufficient and in the range 9-15 angstrom depending on organoclay and filler loading. Overall thermal stability of nanocomposites increases by 16-30 degrees C. The enhancement in T-g of nanocomposite is merely by 2-4 degrees C. With increase in clay loading, tensile modulus increases linearly while % break strain decreases. Break stress is found to increase till 4 wt % and further decreases at higher clay loadings. The overall improvement in thermal and mechanical properties was higher for the organoclay containing organic modifier with lower hydrophobicity and single tallow amine chemical structure. (c) 2007 Wiley Periodicals, Inc.

10amechanical properties10aNanocomposites10aorganoclay10astructure10aThermal properties1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/influence-organic-modification-mechanical-properties-melt-processed-intercalated-002501nas a2200217 4500008004100000022001400041245013400055210006900189260006800258300001400326490000800340520167400348653000902022653001102031653001502042653003102057653002202088100002502110700002302135856012502158 2008 eng d a0021-899500aEffect of organic modifiers and silicate type on filler dispersion, thermal, and mechanical properties of ABS-Clay nanocomposites0 aEffect of organic modifiers and silicate type on filler dispersi a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcNOV a2374-23830 v1103 a

Acrylonitrile-butadiene-styrene (ABS)-clay composite and intercalated nanocomposites were prepared by melt processing, using Na-montmorillonite (MMT), several chemically different organically modified MMT (OMMT) and Na-laponite clays. The polymer-clay hybrids were characterized by WAXD, TEM, DSC, TGA, tensile, and impact tests. Intercalated nanocomposites are formed with organoclays, a composite is obtained with unmodified MMT, and the nanocomposite based on synthetic laponite is almost exfoliated. An unintercalated nanocomposite is formed by one of the organically modified clays, with similar overall stack dispersion as compared to the intercalated nanocomposites. T, of ABS is unaffected by incorporation of the silicate filler in its matrix upto 4 wt % loading for different aspect ratios and organic modifications. A significant improvement in the onset of thermal decomposition (40-44 degrees C at 4 wt % organoclay) is seen. The Young's modulus shows improvement, the elongation-at-break shows reduction, and the tensile strength shows improvement. Notched and unnotched impact strength of the intercalated MMT nanocomposites is lower as compared to that of ABS matrix. However, laponite and overexchanged organomontmorillonite clay lead to improvement in ductility. For the MMT clays, the Young's modulus (E) correlates with the intercalation change in organoclay interlayer separation (Delta d(001)) as influenced by the chemistry of the modifier. Although ABS-laponite composites are exfoliated, the intercalated OMMT-based nanocomposites show greater improvement in modulus. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110:2374-2383, 2008

10aclay10afiller10amechanical10astructure characterization10astyrene-butadiene1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/effect-organic-modifiers-and-silicate-type-filler-dispersion-thermal-and-mechanical-002143nas a2200205 4500008004100000022001400041245012900055210006900184260008600253300001400339490000700353520131100360653002101671653002701692653002101719653001801740100002401758700002301782856013201805 2008 eng d a0022-234800aMonte carlo simulations of chain dimensions and conformational properties of various poly(n-alkyl methacrylates) in solution0 aMonte carlo simulations of chain dimensions and conformational p a325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USAbTAYLOR & FRANCIS INCcOCT a1075-10860 v473 a

Rotational Isomeric State (RIS) Metropolis Monte Carlo (RMMC) simulations of the conformational properties and chain dimensions of a series of chemically different poly(n-alkyl methacrylates) including poly(methyl methacrylate), poly(n-butyl methacrylate), poly(n-hexyl methacrylate), and poly(phenyl methacrylate), in the theta state were investigated, and (r(2)/M)(1/2), (s(2)/M)(1/2) and C(n) were calculated and compared in order to obtain fundamental understanding of the influence of the chemical structure. Simulations were conducted for different molecular weights. Results obtained from the simulations are compared with experimentally obtained dimensions in the literature using the Mark-Houwink relationship as well as, in some cases, data available from direct determinations in theta solvents. Good agreement between simulation and experimental data was obtained. The backbone conformation is predominantly trans in these polymers. Increase in bulkiness and rigidity of the substituting acrylate side group results in an increase in trans and a decrease in gauche backbone conformer population. In the case of rotatable bonds in the side-group structure, increase in rigidity of the side group leads to a decrease in the trans population, although this effect is not uniformly observed.

10achain dimensions10aMonte Carlo simulation10apolymethacrylate10atheta solvent1 aKaryappa, Rahul, B.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/monte-carlo-simulations-chain-dimensions-and-conformational-properties-various-polyn-alkyl-002294nas a2200241 4500008004100000022001400041245012300055210006900178260006800247300001400315490000800329520139100337653002601728653001901754653001501773653002601788653001601814653002301830100002501853700002301878700002301901856012801924 2008 eng d a0021-899500aNew poly(phenylene oxide)/polystyrene blend nanocomposites with clay: intercalation, thermal and mechanical properties0 aNew polyphenylene oxidepolystyrene blend nanocomposites with cla a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY a1818-18280 v1083 a

We present the first study and results on the preparation and characterization of montmorillonite clay filter based polymer blend nanocomposites of the miscible poly(phenylene oxide)/polystyrene blend. Intercalated nanocomposites, prepared by a melt-processing method with 2-6 wt % commercially available organically modified sodium montmorillonite, have been characterized with wide-angle X-ray diffraction, transmission electron microscopy analysis, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), and mechanical tensile tests. We show that nanocomposites can be successfully prepared in a batch mixer at temperatures much below the conditions conventionally used for this blend without organic degradation. Thermal stability is enhanced by nanoscale hybrid formation. The level of intercalation (change in the d-spacing) does not change with the clay loading. Better dispersion of clay in the blend matrix has been observed at a low level of clay content. The nanocomposites show improved tensile modulus (by 31%) in comparison to the blend, whereas the tensile strength (stress at break) and elongation decrease in the presence of the filler with an increase in the clay loading. The Halpin-Tsai model is able to predict the modulus of the nanocomposites in very good agreement with the experimental data. (c) 2008 Wiley Periodicals, Inc.

10amechanical properties10aNanocomposites10aorganoclay10apoly(phenylene oxide)10aPolystyrene10aThermal properties1 aTiwari, Rajkiran, R.1 aKhilar, Kartic, C.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/new-polyphenylene-oxidepolystyrene-blend-nanocomposites-clay-intercalation-thermal-and-001793nas 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

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.

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-002747nas a2200217 4500008004100000022001400041245015700055210006900212260009800281300001200379490000700391520185900398653002002257653002602277653001902303653000902322653002302331100002502354700002302379856012702402 2008 eng d a0959-810300aThermal and mechanical properties of melt processed intercalated poly(methyl methacrylate)-organoclay nanocomposites over a wide range of filler loading0 aThermal and mechanical properties of melt processed intercalated aTHE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLANDbJOHN WILEY & SONS LTDcMAY a738-7430 v573 a

BACKGROUND: Poly(methyl methacrylate) (PMMA)-organoclay nanocomposites with octadecylammonium, ion-modified montmorillonite, prepared via melt processing, over a wide range of filler loading (2-16 wt%) were investigated in detail. These hybrids were characterized for their dispersion structure, and thermal and mechanical properties, such as tensile modulus (E). break stress (sigma(brk)), percent break strain (epsilon(brk)) and ductility(J), using wide-angle X-ray diffraction, transmission electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile and impact tests. RESULTS: Intercalated nanocomposites were formed even in the presence of 16 wt% clay (high loading) in PMMA matrix. PMMA intercalated into the galleries of the organically modified clay, with a change in d-spacing in the range 11-16 angstrom. TGA results showed improved thermal stability of the nanocomposites. The glass transition temperature (T-g) of the nanocomposites, from DSC measurements, was 2-3 degrees C higher than that of PMMA. The ultimate tensile strength and impact strength decreased with increasing clay fraction. Tensile modulus for the nanocomposites increased by a significant amount (113%) at the highest level of clay fraction (16 wt%) studied. CONCLUSION: We show for the first time the formation of intercalated PMMA nanocomposites with alkylammonium-modified clays at high clay loadings (> 15wt%). Tensile modulus increases linearly with clay fraction, and the enhancement in modulus is significant. A linear correlation between tensile strength and strainat-break is shown. Thermal properties are not affected appreciably. Organoclay can be dispersed well even at high clay fractions to form nanocomposites with superior bulk properties of practical interest. (c) 2007 Society of Chemical Industry.

10aimpact strength10amechanical properties10aNanocomposites10aPMMA10aThermal properties1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/thermal-and-mechanical-properties-melt-processed-intercalated-polymethyl-methacrylate-002005nas a2200157 4500008004100000022001400041245017700055210006900232260007600301300001200377490000700389520127500396100002501671700002301696856012801719 2011 eng d a0032-388800aEffect of blend composition and organoclay loading on the nanocomposite structure and properties of miscible poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blends0 aEffect of blend composition and organoclay loading on the nanoco aCOMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USAbWILEY-BLACKWELLcMAY a979-9910 v513 a

Organically-modified montmorillonite clay nanocomposites of poly(styrene-co-acrylonitrile) (SAN), poly(methyl methacrylate) (PMMA) and SAN/PMMA miscible blend are investigated. Structure characteristics at the nanoscale and microscale and thermal and tensile properties are studied as a function of polymer blend composition and filler loading fraction. Blend miscibility and T(g) are unaffected by up to 10% by wt. organoclay. Thermal degradation stability increases with SAN content and exhibits an optimum value of clay loading. Stiffness shows significant improvement. Tensile strength and elongation-at-break suffer as a result of nanocomposite formation. Modulus shows a maximum enhancement of 57% (5 +/- 0.06 GPa at 10 wt% filler, 20/80 SAN/PMMA) and varies linearly with clay fraction for all compositions of matrix phase. Predictions of Halpin-Tsai composite model are in excellent agreement with the experimental behavior over full range of polymer blend composition. Fundamental aspects of a polymer blend-clay nanocomposite are clarified, such as lack of additional synergy between clay platelets and matrix, and tensile ductility reduction, compared with polymer-clay system. POLYM. ENG. SCI., 51:979-991, 2011. (C) 2011 Society of Plastics Engineers

1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/effect-blend-composition-and-organoclay-loading-nanocomposite-structure-and-properties-002058nas a2200157 4500008004100000022001400041245008700055210006900142260007100211300001400282490000800296520144200304100002001746700002301766856011101789 2011 eng d a1520-610600aEffect of chemical substituents on the structure of glassy diphenyl polycarbonates0 aEffect of chemical substituents on the structure of glassy diphe a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB a1579-15890 v1153 a

Polycarbonates offer a wide variety of physical property behavior that is difficult to predict due to complexities at the molecular scale. Here, the physical structure of amorphous glassy polycarbonates having aliphatic and cycloaliphatic chemical groups is explored through atomistic simulations. The influence of chemical structure on solubility parameter, torsion distributions, radial distribution function, scattering structure factor; orientation distributions of phenylene rings and carbonate groups, and free volume distributions, leading to interchain packing effects, are shown. The effect of the cyclohexyl ring at the isopropylidene carbon as compared to the effect of the methyl groups positioned on the phenylene rings results in a larger reduction in the solubility parameter (delta). The interchain distance estimated for polycarbonates in this work is in the range of 5-5.8 angstrom. The o-methyl groups on the phenylene, rings, as compared to a cyclohexyl ring, lead to higher interchain distances. The highest interchain distance is observed with a trimethylcyclohexylidene group at the isopropylidene carbon. Atomistic simulations reveal two different types of packing arrangement of nearest neighbor chains in the glassy state, one type of which agrees with the NMR experimental data The fundamental insights provided here can be utilized for design of chemical structures for tailored macroscopic properties.

1 aSulatha, M., S.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/effect-chemical-substituents-structure-glassy-diphenyl-polycarbonates-001857nas a2200229 4500008004100000022001400041245011600055210006900171260008600240300001300326490000700339520098100346653002101327653001601348653003001364653001601394653002101410653002101431100002401452700002301476856012801499 2011 eng d a0022-234800aEffect of composition on chain dimensions of styrene-methylmethacrylate random copolymers under theta condition0 aEffect of composition on chain dimensions of styrenemethylmethac a325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USAbTAYLOR & FRANCIS INCcAPR a996-10050 v503 a

Rotational-isomeric-state (RIS)-Metropolis Monte Carlo simulations are performed on poly(styrene-ran-methylmethacrylate) random copolymers to study the intrinsic unperturbed (theta-condition) dimensions. Mean-squared end-to-end distance (< r(2)>(o)), mean-squared radius of gyration (< s(2)>(o)), and characteristic ratio (C(n)) have been calculated for these copolymers constituted by different overall chemical compositions (styrene fractions 0.29, 0.56, and 0.70). Calculations were carried out with chains of 500 repeating units. With an increase in the styrene content there is an increase in (< r(2)>(o)), `, and C(n), in agreement with experimental observations. An increase in the fraction of trans conformational states in the backbone torsion angles is found to be responsible for the exhibited chain expansion behavior. The dimensions calculated by the Monte Carlo simulations agree well with experimental values reported in the literature.

10achain dimensions10aMonte Carlo10apoly(methyl methacrylate)10aPolystyrene10arandom copolymer10atheta conditions1 aKaryappa, Rahul, B.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/effect-composition-chain-dimensions-styrene-methylmethacrylate-random-copolymers-under-001529nas a2200217 4500008004100000022001400041245010200055210006900157260006700226300001400293490000800307520070200315653002101017653001801038653002701056653003601083653001801119100002401137700002301161856012701184 2012 eng d a0021-899500aMolecular simulations of the conformational properties of atactic poly(2-ethylbutyl methacrylate)0 aMolecular simulations of the conformational properties of atacti a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcJUL a1586-15910 v1253 a

RIS Metropolis Monte Carlo (RMMC) simulations were used to determine the unperturbed theta-state chain dimensions of atactic stereoconfigurations of poly (2-ethylbutyl methacrylate) [PEBMA]. Root mean-squared end-to-end distance (< r(2)>(o)/M)(1/2) and characteristic ratio (Cn) were calculated along with the backbone torsion angle distribution. The simulated properties are in very good agreement with experimental results. The values of the PEBMA chain dimensions are in-between those corresponding ones for poly(n-butyl methacrylate) and poly (n-hexyl methacrylate) thereby showing the effect of branching in the side-chain. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

10achain dimensions10aconformations10aMonte Carlo simulation10apoly(2-ethylbutyl methacrylate)10avinyl polymer1 aKaryappa, Rahul, B.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/molecular-simulations-conformational-properties-atactic-poly2-ethylbutyl-methacrylate-002197nas a2200253 4500008004100000022001400041245013900055210006900194260008600263300001400349490000700363520124800370653002001618653002501638653002101663653001701684653002301701653001801724653001901742653001201761100002601773700002301799856012101822 2012 eng d a0022-234800aPrediction of structure and energy of trans-1,4-polybutadiene glassy surface by atomistic simulations of free-standing ultrathin films0 aPrediction of structure and energy of trans14polybutadiene glass a325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USAbTAYLOR & FRANCIS INCcMAR a2201-22210 v513 a

Atomistic modeling of amorphous trans-1,4-polybutadiene (TPBD), using molecular mechanics and molecular dynamics (MD) simulations, is performed to generate three-dimensionally periodic bulk and two-dimensionally periodic thin film condensed phases. The condensed structures are constructed using multiple polymer chains. Structural and energetic relaxations and sampling of properties are performed using MD in the canonical ensemble (NVT) by a procedure that relieves local high-energy spots and brings the system to realistic thermodynamic states. The calculated surface energy for TPBD, 30.72 erg/cm(2), is in excellent agreement with the reported experimental value of 31 erg/cm(2). The structure of the surface layers is probed in terms of the atomic mass density variations, bond-bond orientation function profiles, and the distribution of the dihedral angles about the rotatable backbone bonds. The thickness of the surface layer over which the density varies smoothly but rapidly is found to be approximately 15 angstrom. The level of agreement of the calculated surface energy with the experimental value is superior in comparison to previous investigations in the literature using the atomistic approach for flexible polymers.

10a4-polybutadiene10aatomistic simulation10abond-orientation10aConformation10amolecular dynamics10apolymer glass10asurface energy10atrans-11 aIjantkar, Ashwini, S.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/prediction-structure-and-energy-trans-14-polybutadiene-glassy-surface-atomistic-002289nas a2200229 4500008004100000022001400041245013800055210006900193260008700262300001200349490000700361520139900368653001101767653001401778653001501792653002601807653001901833653003001852100002501882700002301907856012901930 2013 eng d a0892-705700aEffect of organic modification on the intercalation and the properties of poly(phenylene oxide)/polystyrene blend-clay nanocomposites0 aEffect of organic modification on the intercalation and the prop a1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLANDbSAGE PUBLICATIONS LTDcAPR a392-4150 v263 a

Nanocomposites prepared by the dispersion of unmodified and organically modified montmorillonite (MMT) clay into poly(2,6-dimethyl phenylene oxide)/polystyrene miscible blend in the range of 2-10 wt% clay were investigated by wide-angle x-ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis and tensile mechanical tests. The systems based on unmodified sodium MMT (Na+MMT) as well as Cloisite 20A, Cloisite 30B and Cloisite 10A organically modified clays showed polymer intercalation. The glass transition temperature (T-g) value was not affected by the volume fraction of clay and chemical nature of the organoclay. The thermal degradation stability of nanocomposites is found to be only slightly better than that of the blend matrix. A percolation threshold of around 4 wt% organoclay loading is observed. An improvement of 35% relative to unfilled polymer blend matrix is observed for the modulus, for Cloisite 20A nanocomposite containing 2 wt% organoclay. The observed modulus improvement with significant retention of elongational tensile strength and tensile ductility in case of unmodified Na-MMT and Cloisite 30B nanocomposites appears promising. The modulus prediction using Halpin-Tsai model is found to be closer to the experimental data when MMT volume fraction rather than the organoclay volume fraction is used.

10afiller10ainterface10ainterphase10amechanical properties10aNanostructures10aPolymer-matrix composites1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/effect-organic-modification-intercalation-and-properties-polyphenylene-oxidepolystyrene-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

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.

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