@article { ISI:000263212700021,
	title = {Effect of gamma-dose rate on crystallinity and morphological changes of gamma-sterilized biomedical polypropylene},
	journal = {Polymer Degradation and Stability},
	volume = {94},
	number = {2},
	year = {2009},
	month = {FEB},
	pages = {272-277},
	publisher = {ELSEVIER SCI LTD},
	address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND},
	abstract = {<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>},
	keywords = {Crystallinity, Dose rate, Gamma radiation, mechanical properties, Morphology, polypropylene},
	issn = {0141-3910},
	doi = {10.1016/j.polymdegradstab.2008.10.027},
	author = {Alariqi, Sameh A. S. and Kumar, A. Pratheep and Rao, B. S. M. and Singh, R. P.}
}
@article {42786,
	title = {Synthesis and characterization of cholesteric thermotropic liquid crystalline polyesters based on isosorbide},
	journal = {Materials Sciences and Applications},
	volume = {2},
	year = {2011},
	month = {OCT},
	pages = {1520-1527},
	abstract = {<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 {\textquotedblleft}yellow iridescent oily streaks{\textquotedblright} 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 300oC 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 300oC. Main chain cholesteric thermotropic liquid crystalline polymers are soluble in aprotic solvents like DMAC, DMSO, DMF and NMP</p>},
	keywords = {Cholesteric, Crystallinity, differential scanning calorimetry, Inherent   Viscosity, Liquid Crystalline Polymers, Optical   Microscopy, Solubility and Solution Polycondensation, Thermo Gravimetric Analysis, thermotropic, Wide Angle X-Ray Diffraction},
	doi = {10.4236/msa.2011.210205},
	author = {Chavan, Nayaku}
}
