01630nas a2200157   4500008004100000022001400041245013300055210006900188260007100257300001200328490000700340520096900347100001701316700001501333856012401348       2005                        eng d  a0024-929700aStudies on the crystallization behavior of nylon-6 in the presence of layered silicates using variable temperature WAXS and FTIR0 aStudies on the crystallization behavior of nylon6 in the presenc  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN  a454-4620 v383 a<p>The crystallization of nylon-6 clay nanocomposite was studied by variable temperature wide-angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR). Nylon-6 was found to crystallize into gamma phase at 210 degreesC, as indicated by its characteristic peaks in WAXS. However, an additional peak was observed close but on the lower angle side of the main gamma phase peak, indicating the presence of a metastable phase. The extent of metastable phase that developed was dictated by the clay content in the nanocomposite as well as the crystallization conditions. The temperature dependence of the d spacing of the gamma phase obtained in the presence of clay layers showed difference from the gamma phase obtained by treating nylon-6 in KI/I-2 solution. Variable temperature FTIR studies were conducted on the gamma phases for the first time, and it showed definite differences in the spectra of the phases obtained by the two methods.</p>1 aNair, S., S.1 aRamesh, C.  uhttps://library.ncl.res.in/content/studies-crystallization-behavior-nylon-6-presence-layered-silicates-using-variable-001970nas a2200169   4500008004100000022001400041245006800055210006600123260007100189300001400260490000700274520137000281100001701651700001501668700001601683856010101699       2006                        eng d  a0024-929700aCrystalline phases in nylon-11: studies using HTWAXS and HTFTIR0 aCrystalline phases in nylon11 studies using HTWAXS and HTFTIR  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR  a2841-28480 v393 a<p>Nylon-11 was crystallized into different crystalline phases by appropriate methods. The chance in the structure during heating was monitored in situ by wide-angle X-ray scattering (WAXS). The alpha phase obtained by precipitating nylon-11 in 1,4-butanediol started transforming into the pseudohexagonal phase on heating, but the transformation was not fully completed before melting. The melt crystallized sample at 175 degrees C gave the pseudohexagonal phase, which transformed into the alpha' phase on cooling to room temperature at about 100 degrees C. The d spacing of the 00 1 reflection also showed a change at the transition temperature. The melt-quenched sample showed the pseudohexagonal phase, which did not change during heating, but on cooling transformed into alpha' phase. The gamma phase was obtained by casting nylon-11 in trifluoroacetic acid (TFA), and it changed into the pscudohexagonal phase at about 110 degrees C on heating. The d spacing of the 001 reflection depended on the way in which it was obtained. The studies have shown that nylon-11 is one of the few nylons that exhibit an extensive degree of polymorphism. High-temperature Fourier transform infrared spectroscopy (HTFTIR) studies revealed, apart from the conformational differences between various phases of nylon-11, some information on the formation of the gamma phase.</p>1 aNair, S., S.1 aRamesh, C.1 aTashiro, K.  uhttps://library.ncl.res.in/content/crystalline-phases-nylon-11-studies-using-htwaxs-and-htftir-002014nas a2200253   4500008004100000022001400041245010500055210006900160260007300229300001200302490000800314520111200322653001501434653002401449653001801473653001901491653001101510100001501521700001701536700001701553700002501570700003301595856013201628       2006                        eng d  a0304-885300aFinite size effects on the structural and magnetic properties of sol-gel synthesized NiFe2O4 powders0 aFinite size effects on the structural and magnetic properties of  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a190-1950 v3023 a<p>Nanoparticles of nickel ferrite have been synthesized by the sol-gel method and the effect of grain size oil its structural and magnetic properties have been Studied in detail. X-ray diffraction (XRD) studies revealed that all the samples are single phasic possessing the inverse spinel structure. Grain size of the sol-gel synthesized powders has been determined from the XRD data and the strain graph. A grain size of 9 nm was observed for the as prepared powders of NiFe2O4 obtained through the sol-gel method. It was also observed that strain was induced during the firing process. Magnetization measurements have been carried out on all the samples prepared in the present series. It was found that the specific magnetization of the nanosized NiFe2O4 powders was lower than that of the corresponding coarse-grained counterparts and decreased with a decrease in grain size. The coercivity of the sol-gel synthesized NiFe2O4 nanoparticles attained a maximum value when the grain size was 15 nm and then decreased as the grain size was increased further. (c) 2005 Elsevier B.V. All rights reserved.</p>10agrain size10amagnetic properties10aNanoparticles10aNickel ferrite10astrain1 aGeorge, M.1 aJohn, A., M.1 aNair, S., S.1 aJoy, Pattayil, Alias1 aAnantharaman, Maliemadom, R.  uhttps://library.ncl.res.in/content/finite-size-effects-structural-and-magnetic-properties-sol-gel-synthesized-nife2o4-powders-0