02184nas a2200241 4500008004100000022001400041245011100055210006900166260009900235300001400334490000700348520126300355653001901618653001901637653003401656653002401690653001601714100002601730700001801756700001901774700001801793856013101811 2006 eng d a0141-391000aBiodegradation of gamma-sterilised biomedical polyolefins under composting and fungal culture environments0 aBiodegradation of gammasterilised biomedical polyolefins under c aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAY a1105-11160 v913 a

Polyolefin-based commodities are widely used as biomedical devices and food packaging after gamma-sterilisation. The aim of the present work was to study the effect of gamma-sterilisation on the biodegradation of polyolefins. Films of isotactic polypropylene, high-density polyethylene and ethylene-propylene (EP) copolymers were sterilised under gamma-radiation with doses of 10 and 25 kGy. Neat and sterilised samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and chain scission in polymer chains were characterized by FTIR spectroscopy, SEM and viscometric measurements, respectively. A gradual decrease in intrinsic viscosity [eta] and increase in carbonyl and hydroxyl regions in FTIR spectra were found for the gamma-sterilised samples as a function of increasing dose. Polypropylene was found to be more susceptible to both radio-oxidation and biodegradation. It was observed that in case of ethylene-propylene copolymers, extent of gamma-sterilisation and/or biodegradation depends on the composition and distribution of comonomers. Important surface erosion was detected by SEM, for higher sterilisation doses, after composting. (c) 2005 Elsevier Ltd. All rights reserved.

10aBiodegradation10achain scission10aComposting and fungal culture10agamma-sterilisation10aPolyolefins1 aAlariqi, Sameh, A. S.1 aKumar, A., P.1 aRao, B., S. M.1 aSingh, R., P. uhttp://library.ncl.res.in/content/biodegradation-gamma-sterilised-biomedical-polyolefins-under-composting-and-fungal-culture-102018nas a2200217 4500008004100000022001400041245009200055210006900147260006800216300001400284490000800298520122500306653001301531653001601544653003301560100002401593700002301617700001801640700002201658856012001680 2008 eng d a0021-899500aModeling of a fluidized bed propylene polymerization reactor operated in condensed mode0 aModeling of a fluidized bed propylene polymerization reactor ope a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY a2067-20760 v1083 a

The gas-phase polymerization of propylene is one of the most widely accepted and commercially used processes for the manufacture of polypropylene (PP). Because of the highly exothermic nature of polymerization reactions, temperature runaway and subsequent polymer melting and agglomeration may occur, and the reactor has to be operated in a small operating window for safety. The addition of liquid monomer for heat removal (condensed mode) broadens the operating window and can substantially increase (by 50-100%) the capacity of given reactor hardware. This article describes the extension of a comprehensive mathematical model for the simulation of fluidized bed PP reactors to include the condensed mode of operations. The model is used to determine the influence of the operating parameters on the polymer properties and particle size distribution. The model is also used to determine the effects of two active sites and the reaction kinetics on macroscopic variables. The developed framework is useful for simulating multimonomer, multisite Ziegler-Natta-type olefin fluidized bed polymerization reactors operated under condensed mode. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 108: 2067-2076, 2008.

10aModeling10aPolyolefins10aZiegler-Natta polymerization1 aUtikar, Ranjeet, P.1 aHarshe, Yogesh, M.1 aMehra, Anurag1 aRanade, Vivek, V. uhttp://library.ncl.res.in/content/modeling-fluidized-bed-propylene-polymerization-reactor-operated-condensed-mode-001725nas a2200217 4500008004100000022001400041245009100055210006900146260007500215300001200290490000700302520092900309653001901238653003401257653002001291653001601311653001801327100002601345700001801371856011801389 2010 eng d a1566-254300aEffect of gamma-dose rate on biodegradation of gamma-sterilized biomedical polyolefins0 aEffect of gammadose rate on biodegradation of gammasterilized bi a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScDEC a600-6070 v183 a

The aim of the present study is to study the effect of gamma-dose rate on the biodegradation of gamma-sterilized polyolefins. Films of isotactic polypropylene, high density polyethylene and ethylene-propylene (EP) copolymer were sterilized under gamma-radiation with doses of 10 and 25 kGy. Two different (60)Co sources were used with dose rate 600 and 780 Gy h(-1). Neat and sterilized samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and intrinsic viscosity in polymer chains were characterized by FT-IR spectroscopy, SEM and viscometric measurements, respectively. It was observed that both gamma-degradation and biodegradation processes depend on the dose rate of gamma-source. It was found that the biodegradation of gamma-sterilized polyolefins in composting and microbial culture environments increased with decreasing the gamma-dose rate.

10aBiodegradation10aComposting and fungal culture10agamma-Dose rate10aPolyolefins10aSterilization1 aAlariqi, Sameh, A. S.1 aSingh, R., P. uhttp://library.ncl.res.in/content/effect-gamma-dose-rate-biodegradation-gamma-sterilized-biomedical-polyolefins-0