02478nas a2200265   4500008004100000022001400041245011100055210006900166260009900235300001400334490000700348520149400355653001701849653001801866653003301884653002401917653001801941653002301959100002601982700002002008700001902028700002102047700001802068856012602086       2006                        eng d  a0141-391000aStabilization of gamma-sterilized biomedical polyolefins by synergistic mixtures of oligomeric stabilizers0 aStabilization of gammasterilized biomedical polyolefins by syner  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcOCT  a2451-24640 v913 a<p>The stabilization of polyolefins against gamma-sterilization has been studied with single or binary additive system. The present attempt is to utilize synergistic mixtures of stabilizers which are approved for food contact applications. Ethylene-propylene (EP) copolymer has been melt-mixed with hindered amine stabilizers (HAS), phenolic antioxidants and organo-phosphites (hydroperoxide decomposer). Samples were sterilized with different doses of gamma-radiation. Stabilization was characterized in terms of changes in the functional groups (oxidation products), tensile properties, yellowing and surface morphology by FTIR spectroscopy, Instron, colorimetry (reflectance) and scanning electron microscopy (SEM), respectively. Results were discussed by comparing the stabilizing efficiency of mixtures with and without phenol system. Among phenol containing systems, where we mostly observe discoloration due to the oxidation of hindered phenol and the combination of secondary HAS, tertiary HAS, organo-phosphite and hindered phenol exhibited improved stabilization efficiency than single or binary additive systems. The mixture of secondary HAS and tertiary HAS, has shown antagonistic effect of stabilization whereas their combination with organo-phosphite has exhibited synergistic effect of stabilization even at higher doses of gamma-sterilization. The effects have been explained through the interaction between the stabilizers. (c) 2006 Elsevier Ltd. All rights reserved.</p>10aAntioxidants10adiscoloration10aethylene-propylene copolymer10agamma-sterilization10astabilization10atensile properties1 aAlariqi, Sameh, A. S.1 aKumar, Pratheep1 aRao, B., S. M.1 aTevtia, Amit, K.1 aSingh, R., P.  uhttp://library.ncl.res.in/content/stabilization-gamma-sterilized-biomedical-polyolefins-synergistic-mixtures-oligomeric-201800nas a2200253   4500008004100000022001400041245011900055210006900174260006800243300001400311490000800325520084700333653002601180653003401206653001901240653001801259653003801277100002201315700002001337700002001357700002101377700001801398856013001416       2007                        eng d  a0021-899500aSynthesis and characterization of hindered amine light stabilizers based on end functionalization of polypropylene0 aSynthesis and characterization of hindered amine light stabilize  a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY  a1596-16020 v1043 a<p>A polymeric hindered amine light stabilizer (HALS), where HALS moiety was attached at the terminal end of the polypropylene chain via end-functionalized vinylidine PP through simple organic reactions, was synthesized. It comprises the synthesis of vinylidine-terminated polypropylene by using Cp2ZrCl2/MAO as catalyst system and epoxidation of vinylidene polypropylene. The final product was synthesized by carrying out the reaction between epoxy end functionalized polypropylene and 4-amino-2,2,6,6-tetrametyl piperidine. The final product was characterized by using H-1 NMR, C-13 NMR, and FT-IR spectra. Functionality was calculated by using vapor phase osmometry and H-1 NMR. The solubility and diffusion coefficient of the product were calculated and also its stabilization performance was checked. (c) 2007 Wiley Periodicals, Inc.</p>10aend functionalization10afunctionalization of polymers10apolymeric HALS10apolypropylene10avinylidine and photostabilization1 aReddy, Raghunatha1 aKumar, Bijendra1 aRana, Sravendra1 aTevtia, Amit, K.1 aSingh, R., P.  uhttp://library.ncl.res.in/content/synthesis-and-characterization-hindered-amine-light-stabilizers-based-end-functionalization