02005nas a2200253   4500008004100000022001400041245011800055210006900173260009900242300001200341490000700353520106500360653001801425653001401443653002001457653002601477653001501503653001801518100002601536700002001562700001901582700001801601856013201619       2009                        eng d  a0141-391000aEffect of gamma-dose rate on crystallinity and morphological changes of gamma-sterilized biomedical polypropylene0 aEffect of gammadose rate on crystallinity and morphological chan  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcFEB  a272-2770 v943 a<p>The present work is aimed to study the changes in crystallinity and morphology of biomedical polyolefins after gamma-sterilization. The isotactic polypropylene (iPP) films were sterilized by gamma-radiation and the changes were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and atomic force microscopy (AFM) techniques. The effect of dose rate on crystallinity changes also was focused. It was found that crystallinity and morphology significantly changed with gamma-irradiation. There was an increase in crystallinity Lip to 10 kGy accompanied with decrease in viscosity and mechanical properties. The changes in crystallinity mainly depend on gamma-irradiation dose and dose rate. The rise in crystallinity was attributed to chain scission and forming new perfect lamellae. However, the reduction was accompanied by occurrence of gamma- and beta-phases and crosslinking. Possible explanations for transitions in phases are also discussed based on our results. (C) 2008 Elsevier Ltd. All rights reserved.</p>10aCrystallinity10aDose rate10aGamma radiation10amechanical properties10aMorphology10apolypropylene1 aAlariqi, Sameh, A. S.1 aKumar, Pratheep1 aRao, B., S. M.1 aSingh, R., P.  uhttps://library.ncl.res.in/content/effect-gamma-dose-rate-crystallinity-and-morphological-changes-gamma-sterilized-biomedical-002761nas a2200253   4500008004100000245011300041210006900154260000800223300001400231490000600245520182500251653001602076653001802092653003802110653002502148653003202173653002502205653004502230653003202275653001702307653003302324100001902357856013102376       2011                        eng d00aSynthesis and characterization of cholesteric thermotropic liquid crystalline polyesters based on isosorbide0 aSynthesis and characterization of cholesteric thermotropic liqui  cOCT  a1520-15270 v23 a<p>Generally main chain cholesteric thermotropic liquid crystalline polymers are prepared form chiral dia-cid or diol monomer. But these monomers are costly. Isosorbide is chiral cycloaliphatic diol accessible from renewable resources in the form of pure enantiomers. Thus it is used to synthesize main chain cholesteric thermotropic liquid crystalline polymers. Incorporation of phenyl hydroquinone into the backbone of the main chain frustrates chain pack-ing, thus lowering the crystallinity and depressing the melting point below the degradation temperature, also improves the solubility due to disruption of packing and maintains the mechanical and thermal performance. Results: Optical microscopy study reveals that more than 50% of isosorbide content with phenyl hydroquinone and terephthalic acid showed “yellow iridescent oily streaks” with a background of mosaic/marble texture. These are the typical textures of cholesteric liquid crystalline phase. Copolyesters based on phenyl hydroquinone, isosorbide and terephthalic acid are soluble in aprotic solvents like N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP). Solubility increases with the content of isosorbide percent. Thermal stabil-ity of all copolyesters was more than 300˚C on the basis of 10 wt% loss. Conclusions: It was found that main chain cholesteric thermotropic liquid crystalline polymers can be prepared form chiral cycloaliphatic diol such as isosorbide. Main chain cholesteric thermotropic liquid crystalline polyesters are prepared from phenyl hydroquinone, isosorbide and terephthalic acid showed thermal stability more than 300˚C. Main chain cholesteric thermotropic liquid crystalline polymers are soluble in aprotic solvents like DMAC, DMSO, DMF and NMP</p>10aCholesteric10aCrystallinity10adifferential scanning calorimetry10aInherent   Viscosity10aLiquid Crystalline Polymers10aOptical   Microscopy10aSolubility and Solution Polycondensation10aThermo Gravimetric Analysis10athermotropic10aWide Angle X-Ray Diffraction1 aChavan, Nayaku  uhttps://library.ncl.res.in/content/synthesis-and-characterization-cholesteric-thermotropic-liquid-crystalline-polyesters-based