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

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.

1 aNair, S., S.1 aRamesh, C. uhttps://library.ncl.res.in/content/studies-crystallization-behavior-nylon-6-presence-layered-silicates-using-variable-002139nas a2200205 4500008004100000022001400041245026000055210006900315260007300384300001400457490000700471520119000478653001601668653002101684653002701705653003401732100002001766700001501786856013201801 2006 eng d a1381-514800aSynthesis and characterization of main chain thermotropic liquid crystalline polyesters based on methyl 4-[4 `-(omega-hydroxyalkoxy)blphenyl-4-yl]-4-oxobutyrate: Effects of keto group and connectivity on mesophasic characteristics of biphenyl based AB-typ0 aSynthesis and characterization of main chain thermotropic liquid aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcOCT a1003-10130 v663 a

A series of biphenyl based main chain thermotropic liquid crystalline polyesters, poly(hydroxyalkoxybiphenyl oxobutyrate) [PRBOB-2,n (n = 2-8)], containing various methylene spacers was synthesized by using the novel AB-type self-polycondensation route from the monomers, methyl 4-[4'-(omega-hydroxyalkoxy)biphenyl-4-yl]-4-oxobutyrate (HBOB-2,n). The mesophase characteristics of these polyesters was studied using DSC, polarized light optical microscopy and XRD techniques. The transition temperatures were found to decrease upon increasing the spacer length with an even polymer exhibiting higher transition temperature than the odd counterpart. The mesophase type also indicated an odd-even oscillation with the even members showing normal smectic phase and odd members exhibiting tilted smectic phase. The comparison of mesophasic characteristics of these polyesters with that of structurally similar AB-type polyesters indicated that the total number of atoms connecting the mesogen in a polymeric repeat unit governs the nature of the mesophase while the rigidity of the system dictates the magnitude of transition temperatures. (c) 2006 Elsevier B.V. All rights reserved.

10aAB approach10abiphenyl mesogen10aeffect of connectivity10aLiquid crystalline polyesters1 aRanganathan, T.1 aRamesh, C. uhttps://library.ncl.res.in/content/synthesis-and-characterization-main-chain-thermotropic-liquid-crystalline-polyesters-based-101569nas a2200241 4500008004100000022001400041245006100055210006100116260010600177300001200283490000700295520074200302653002201044653001301066653002101079653001701100653003601117653002901153100001601182700001901198700001501217856009501232 2009 eng d a0079-670000aStructural phase transitions of syndiotactic polystyrene0 aStructural phase transitions of syndiotactic polystyrene aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a280-3150 v343 a

Syndiotactic polystyrene (sPS) exhibits four crystal modifications (alpha, beta, gamma, and delta), along with intermediate forms with different molecular conformations, as well as different chain-packing structures. The extensive literature on the crystal structures exhibited by sPS is reviewed herein, including, the mechanisms of phenomena such as solvent-induced crystallization, thermally induced crystallization and gelation, and the phase transitions among the various crystalline forms. The latter have been studied by static and dynamic wide-angle and small-angle X-ray scattering, infrared and Raman spectra, and neutron scattering, etc., in addition to computer simulations. (C) 2009 Elsevier Ltd. All rights reserved.

10acrystal structure10aGelation10aphase transition10apolymorphism10aSolvent-induced crystallization10aSyndiotactic polystyrene1 aGowd, Bhoje1 aTashiro, Kohji1 aRamesh, C. uhttps://library.ncl.res.in/content/structural-phase-transitions-syndiotactic-polystyrene-002029nas a2200253 4500008004100000022001400041245008500055210006900140260009200209300001000301490000800311520115200319653001201471653001601483653001401499653001401513653001401527100002401541700003101565700001501596700002701611700002101638856011601659 2013 eng d a0040-500000aStructure-property relationship of different types of polyester industrial yarns0 aStructureproperty relationship of different types of polyester i a4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLANDbTAYLOR & FRANCIS LTDcJAN a35-450 v1043 a

Four major types of polyester industrial yarns (1000 Denier) which are used commercially were studied for their key structural parameters. An attempt has been made to establish a relationship between morphology and properties of these yarns. High tenacity (HT) polyester yarn has the highest birefringence, amorphous orientation, and long period but is relatively less crystalline. High shrinkage characteristic of HT polyester yarn can be accounted for its higher amorphous orientation. High modulus low shrinkage (HMLS) polyester yarn has higher crystallinity and crystal size compared to HT yarn. Fraction of tie molecules of these yarns has been calculated and found that low shrinkage (LS) and super low shrinkage (SLS) yarns have lesser tie molecules. These LS and SLS yarns are tailor-made to achieve lower shrinkage and at the same time maintaining a good level of tenacity. This is achieved with lower amorphous orientation in the final drawn yarn structure. Amorphous orientation was found to have stronger influence than any other structural parameter on the key yarn properties like modulus, tenacity, elongation, and shrinkage.

10amodulus10aorientation10apolyester10ashrinkage10astructure1 aSamui, Barun, Kumar1 aPrakasan, Manikanda, Priya1 aRamesh, C.1 aChakrabarty, Debabrata1 aMukhopadhyay, R. uhttps://library.ncl.res.in/content/structure-property-relationship-different-types-polyester-industrial-yarns-002059nas a2200265 4500008004100000022001400041245009800055210006900153260009400222300001400316490000800330520114900338653001001487653001201497653001401509653001401523653001401537653001401551100002401565700002101589700002101610700001501631700002701646856012001673 2016 eng d a0040-500000aStudies on the static and dynamic properties of different types of polyester industrial yarns0 aStudies on the static and dynamic properties of different types  a2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLANDbTAYLOR & FRANCIS LTDcOCT a1175-11840 v1073 a

Four major types of polyester industrial yarns, viz. high tenacity (HT), high modulus low shrinkage (HMLS), low shrinkage (LS) and super low shrinkage (SLS) polyester yarns, were studied for their static and dynamic properties. An attempt has been made to establish a linkage between static and dynamic properties of these yarns with its structure and with its end applications. HMLS and HT polyester yarns have lower tan delta and work loss, which are the desired characteristics required for its end applications which include tire and conveyer belt. Higher overall orientation and higher fraction of tie molecules helped to achieve these properties in HT and HMLS polyester yarns. LS and SLS polyester yarns are mostly used for static applications. Low thermal shrinkage is the key requirement for the downstream processes of these yarns. Lower amorphous orientation in these two yarns is primarily responsible for achieving very low thermal shrinkage. A good co-relation has been established between the peak temperature of work loss (in slow speed hysteresis test) and the peak temperature of tan delta (in high-speed dynamic test).

10acreep10amodulus10apolyester10ashrinkage10atan delta10awork loss1 aSamui, Barun, Kumar1 aDasgupta, Saikat1 aMukhopadhyay, R.1 aRamesh, C.1 aChakrabarty, Debabrata uhttps://library.ncl.res.in/content/studies-static-and-dynamic-properties-different-types-polyester-industrial-yarns