02396nas a2200241 4500008004100000022001400041245011200055210006900167260005700236300001200293490000700305520154300312100002201855700001801877700001901895700001801914700001801932700002201950700001801972700002101990700002102011856012202032 2014 eng d a0022-246100aMulti-walled CNT-induced phase behaviour of poly(vinylidene fluoride) and its electro-mechanical properties0 aMultiwalled CNTinduced phase behaviour of polyvinylidene fluorid a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJAN a103-1130 v493 a

A simple two-step process was used to disperse acid functionalizedmulti-walled carbon nanotubes (CNTs) in poly(vinylidene fluoride) (PVDF). While the neat solvent-cast PVDF showed coexistence of alpha- and beta-phases; the composite films exhibited only beta-phase crystals. Further studies on the crystalline behaviour, using differential scanning calorimetry and small-angle X-ray scattering techniques showed an increase in the percentage of crystalline phase with CNT. The network formed by CNTs in the matrix reduced the macroscopic electrical resistivity of composite films. The dielectric constant increased with CNT loading. Further, these composites were investigated for its electromagnetic wave absorbance (EWA) and strain sensing properties. The EWA properties were studied in the X-band (6-12 GHz) region. A maximum of similar to 37 dB reflectivity loss at similar to 9.0 GHz was obtained in a similar to 25 mu m thick PVDF film containing only 0.25 wt% of functionalized CNT. Preliminary studies showed a systematic change in electrical resistance by the application of dynamic bending strain in nanocomposite film. The film also showed a significant improvement in mechanical stiffness owing to efficient stress transfer from matrix to filler, the property desirable for a good strain sensor. In view of the unique combination of EWA and electro-mechanical properties, the nanocomposite films are expected to serve as a multifunctional material for strain sensing in health monitoring as well as in radar absorption.

1 aRath, Sangram, K.1 aDubey, Sachin1 aKumar, Sudheer1 aKumar, Sanjay1 aPatra, A., K.1 aBahadur, Jitendra1 aSingh, A., K.1 aHarikrishnan, G.1 aPatro, Umasankar uhttps://library.ncl.res.in/content/multi-walled-cnt-induced-phase-behaviour-polyvinylidene-fluoride-and-its-electro-002356nas a2200217 4500008004100000022001400041245017300055210006900228260011000297300001400407490000700421520142000428100002201848700002101870700002401891700002201915700002401937700002201961700002401983856013102007 2016 eng d a1463-907600aCharacterizing the nanoclay induced constrained amorphous region in model segmented polyurethane-urea/clay nanocomposites and its implications on gas barrier properties0 aCharacterizing the nanoclay induced constrained amorphous region aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJAN a1487-14990 v183 a

There has been an increasing recognition of the fact that purely geometric factors associated with clay platelet dispersion in a polymer matrix cannot adequately explain the barrier properties of polymer/clay nanocomposites. The objective of the present work is to understand the nanoclay induced structural changes in a polyurethane-urea matrix and clay dispersion at different length scales using segment-specific characterization techniques and implications of the same in gas barrier properties using He, N-2 and CO2 as probe molecules. Wide angle X-ray diffraction (WAXD) and positron annihilation life time spectroscopy (PALS) studies revealed nanoclay induced alterations in the chain packing of the amorphous soft segments of the polyurethane matrix at a molecular scale of a few Angstroms. The hard segment organization and the phase morphology of the nanocomposites, spanning length scales of several nanometers, were investigated by small angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, the presence of a constrained amorphous region surrounding the nanoclay was confirmed from AFM, WAXD and PALS results. Several pertinent structural variables from the gas transport point of view were deduced from these characterization techniques to understand the effect of the barrier properties in tandem with the clay dispersion morphology.

1 aRath, Sangram, K.1 aSudarshan, Kathi1 aBhavsar, Rupesh, S.1 aKharul, Ulhas, K.1 aPujari, Pradeep, K.1 aPatri, Manoranjan1 aKhakhar, Devang, V. uhttps://library.ncl.res.in/content/characterizing-nanoclay-induced-constrained-amorphous-region-model-segmented-polyurethane-002073nas a2200181 4500008004100000022001400041245013100055210006900186260000900255300001600264490000700280520138700287100001801674700002301692700002201715700002301737856013101760 2023 eng d a1463-907600aInvestigation of Al2O3 induced variations in the structural parameters in strontium borosilicate glasses using solid state NMR0 aInvestigation of Al2O3 induced variations in the structural para cMAY  a13550-135590 v253 a

The physical properties of oxide glasses are crucially dependent on the atomistic structural speciation. In this study, we investigate the variation in the local ordering in the glass network of strontium borosilicate glasses (34.82 SrO, 51.84 B2O3, 13.34 SiO2 in mol%) with a progressive substitution of B2O3 by Al2O3 and estimate the structural parameters: the oxygen packing fraction, and the average network coordination number. The coordination of the network forming cations at various glass compositions is determined using B-11, Al-27, and Si-29 solid-state nuclear magnetic resonance (SSNMR). The SSNMR reveals that at the higher substitution of B2O3 by Al2O3 in the glass composition, the coordination network of Al3+ exists predominantly in the 4 coordinated state, the network forming B3+ cations transform from a tetrahedral BO4 to a trigonal BO3 structure, and the Q(4) form of silicates is dominant. The average coordination number and the oxygen packing fraction were calculated using the parameters obtained from the SSNMR results, and it is observed that the average coordination number decreases, and the oxygen packing fraction increases on incorporating Al. It is interesting to note that some of the thermophysical properties of these compositions closely follow the pattern shown by the average coordination number and the oxygen packing fraction.

1 aIllath, Kavya1 aOjha, Prasanta, K.1 aRath, Sangram, K.1 aAjithkumar, T., G. uhttps://library.ncl.res.in/content/investigation-al2o3-induced-variations-structural-parameters-strontium-borosilicate-glasses