02185nas a2200241   4500008004100000022001400041245011100055210006900166260009900235300001400334490000700348520126300355653001901618653001901637653003401656653002401690653001601714100002601730700001801756700001901774700001801793856013201811       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<p>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.</p>10aBiodegradation10achain scission10aComposting and fungal culture10agamma-sterilisation10aPolyolefins1 aAlariqi, Sameh, A. S.1 aKumar, A., P.1 aRao, B., S. M.1 aSingh, R., P.  uhttps://library.ncl.res.in/content/biodegradation-gamma-sterilised-biomedical-polyolefins-under-composting-and-fungal-culture-102479nas a2200265   4500008004100000022001400041245011100055210006900166260009900235300001400334490000700348520149400355653001701849653001801866653003301884653002401917653001801941653002301959100002601982700002002008700001902028700002102047700001802068856012702086       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.  uhttps://library.ncl.res.in/content/stabilization-gamma-sterilized-biomedical-polyolefins-synergistic-mixtures-oligomeric-200891nas a2200229   4500008004100000022001400041245014200055210006900197260007300266300001200339490000700351653001300358653002300371653002400394653001100418653002200429100002600451700002000477700001900497700001800516856012700534       2007                        eng d  a0167-577X00aStabilization of gamma-sterilized biomedical polyolefins by synergistic mixtures of oligomeric stabilizers. part II. polypropylene matrix0 aStabilization of gammasterilized biomedical polyolefins by syner  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB  a299-3090 v9210aCeramics10aChemical synthesis10aElectron microscopy10aOxides10aX-ray diffraction1 aAlariqi, Sameh, A. S.1 aKumar, Pratheep1 aRao, B., S. M.1 aSingh, R., P.  uhttps://library.ncl.res.in/content/stabilization-gamma-sterilized-biomedical-polyolefins-synergistic-mixtures-oligomeric-102005nas 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-001726nas a2200217   4500008004100000022001400041245009100055210006900146260007500215300001200290490000700302520092900309653001901238653003401257653002001291653001601311653001801327100002601345700001801371856011901389       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<p>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.</p>10aBiodegradation10aComposting and fungal culture10agamma-Dose rate10aPolyolefins10aSterilization1 aAlariqi, Sameh, A. S.1 aSingh, R., P.  uhttps://library.ncl.res.in/content/effect-gamma-dose-rate-biodegradation-gamma-sterilized-biomedical-polyolefins-002137nas a2200253   4500008004100000022001400041245012900055210006900184260005700253300001400310490000700324520121300331653001501544653001401559653001901573653001801592653001801610653002201628100003101650700002801681700002601709700002001735856012801755       2010                        eng d  a1598-503200aPreparation and characterization of bioceramic nanocomposites based on hydroxyapatite (HA) and carboxymethyl cellulose (CMC)0 aPreparation and characterization of bioceramic nanocomposites ba  a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcDEC  a1160-11670 v183 a<p>We report the synthesis of biomimetic nanocomposites based on carboxymethyl cellulose (CMC) and hydroxyapatite (HA) nanoparticles via a co-precipitation method. Physico-chemical characterization was performed before and after calcination by Fourier transform infrared (FTIR) spectroscopy, solid state (31)P nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). The formation of nanocomposites was observed by wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The spectral and crystallographic data indicated the formation of hydroxyapatite in the presence of CMC. They were observed as aggregates of HA nanoparticles and CMC, whose sizes were approximately similar to 260 +/- 40 nm. The crystallite size of the hydroxyapatite particles decreased (with 2 wt% 18 +/- 3 nm) with increasing CMC content. The morphological aspects of the calcined samples revealed the sintering ability of HA nanoparticles. Nanocomposites of hydroxyapatite nanoparticles that mimic the process of nucleation and growth in nature can be prepared using biomacromolecules such as CMC.</p>10abiopolymer10acellulose10ahydroxyapatite10aNanoparticles10aParticle size10aX-ray diffraction1 aKumar, Annamalai, Pratheep1 aMohaideen, Kamal, Khaja1 aAlariqi, Sameh, A. S.1 aSingh, Raj, Pal  uhttps://library.ncl.res.in/content/preparation-and-characterization-bioceramic-nanocomposites-based-hydroxyapatite-ha-and-001945nas a2200217   4500008004100000022001400041245009800055210006900153260008000222300001000302490000700312520112900319653003701448653001401485653002201499653001801521100002601539700001801565700001901583856012501602       2011                        eng d  a1319-802500aGamma-initiated oxidation of isotactic polypropylene: effect of gamma-dose rate on durability0 aGammainitiated oxidation of isotactic polypropylene effect of ga  aTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANYbSPRINGER HEIDELBERGcJAN  a29-380 v363 a<p>The effect of gamma-irradiation dose rate on the chemical, molecular, and mechanical properties of isotactic polypropylene (iPP) films was investigated using three different Co-60 sources with dose rates of 600, 660, and 780 Gy h(-1). Fourier transform infrared spectroscopy coupled with chemical derivatization with NO and SF4, and measurements of the elongation at break, toughness, and molecular weight were used to describe the effects of gamma-dose rate on iPP. It was found that the formation of oxidation products depended significantly on the dose rate. However, the kinetic accumulation of ketones were more sensitive to the dose rate of gamma source. Degradation induced by gamma-radiation depends on the dose rate-the degradation of mechanical properties was more significant at a low dose rate than at a high dose rate. It was found that the lower the dose rate, the higher the degree of oxidation in terms of the formation of gamma-products. The mechanism of gamma-degradation is discussed based on the correlation between the changes in chemical and physical properties upon exposure to gamma-radiation.</p>10aChemical and physical properties10aDose rate10agamma-irradiation10apolypropylene1 aAlariqi, Sameh, A. S.1 aSingh, R., P.1 aRao, B., S. M.  uhttps://library.ncl.res.in/content/gamma-initiated-oxidation-isotactic-polypropylene-effect-gamma-dose-rate-durability-002735nas a2200169   4500008004100000245012100041210007000162260000800232300001400240490000600254520207300260100002602333700002802359700002802387700002002415856013002435       2017                        eng d00aStabilization of γ-sterilized low-density polyethylene by synergistic mixtures of food-contact approval stabilizers0 aStabilization of γsterilized lowdensity polyethylene by synergis  cJUN  a145–1560 v83 aIn our previous studies, we have found the synergistic combinations of stabilizers which follow different mechanisms of stabilization and are approved for food contact applications. The present attempt is to test the potentials of those systems in stabilizing γ-sterilized low-density polyethylene (LDPE). The results were discussed by comparing the stabilizing efficiency of mixtures with and without phenol systems as well as with their counterparts of isotactic polypropylene (iPP) and ethylene-propylene copolymers (EP) matrices. LDPE has been melt-mixed with tertiary hindered amine stabilizer (tert-HAS), oligomeric HAS stabilizer, phenolic and organo-phosphite antioxidants and subjected to γ-sterilization. Stabilization in terms of changes in oxidation products, tensile properties, yellowing and surface morphology was evaluated by FT-IR spectroscopy, Instron, colorimetry, and scanning electron microscopy (SEM), respectively. The results of the present study confirm the validity of those systems for protecting various polyolefins against γ-sterilization. The results showed that the synergism, antagonism and the trend in stabilization efficiency of the binary, ternary and quaternary stabilizer systems were almost similar in LDPE, iPP and EP matrices. The binary system of oligomeric HAS and tert-HAS has shown the antagonistic effect of stabilization, whereas their combination with organo-phosphite has exhibited synergistic effect even at higher doses of γ-sterilization. The combination of oligomeric HAS, tert-HAS, organo-phosphite and hindered phenol exhibited improved stabilization efficiency than single or binary additive systems. The phenol systems have shown long term of stability than that of phenol-free systems. It was found that the consumption of oligomeric stabilizer significantly depends on the components of stabilization mixture. It was concluded that the stability of polyolefins (LDPE, iPP and EP) against γ-sterilization can be achieved by blends of different stabilizers which are approved for food contact applications.1 aAlariqi, Sameh, A. S.1 aAl-Areqi, Niyazi, A. S.1 aAlaghbari, Elyas, Sadeq1 aSingh, Raj, Pal  uhttps://library.ncl.res.in/content/stabilization-%CE%B3-sterilized-low-density-polyethylene-synergistic-mixtures-food-contact