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1、PolymerDegradationandStability96(2011)595e607ContentslistsavailableatScienceDirectPolymerDegradationandStabilityjournalhomepage:www.elsevier.com/locate/polydegstabAcceleratedageinganddegradationinpoly-L-lactide/hydroxyapatitenanocompositesClaireDelabarde,ChristopherJ.G.Plummer,Pierre-EtienneBourban
2、,Jan-AndersE.Månson*LaboratoiredeTechnologiedesCompositesetPolymères(LTC),ÉcolePolytechniqueFédéraledeLausanne(EPFL),CH-1015Lausanne,SwitzerlandarticleinfoabstractArticlehistory:Dry,compressionmoldedfilmsofmedicalgradepoly-L-lactide(PLLA)showedamarkedreductioninReceived6October2010tensilestrengthand
3、strainafteracceleratedageinginaqueousNaOHat50C,accompaniedbymassloss,Receivedinrevisedformsurfaceerosion,increasedhydrophilicityand,inthecaseoftheinitiallyamorphousfilms,coldcrystal-7December2010lizationowingtotheplasticizingeffectoftheageingmedium.AdditionofwelldispersednanosizedAccepted27December
4、2010hydroxyapatite(nHA)particlesresultedinincreasesintherateofmasslossduringageing,identifiedAvailableonline13January2011withaccelerateddegradationatthematrix/particleinterfaces.However,theassociateddecreasesintensilestrengthandstraintofailwithageingtimewerefarlessmarkedinthepresenceofthenHAthanKeyw
5、ords:intheunmodifiedfilms.ThisimpliedthatnHAactsasaneffectivetoughenerofthebulkmaterial,AgeingDegradationconsistentwithTEMobservationsofthedeformedfilms,whichindicatedfailureoftheparticleematrixPLLAinterfacestopromoteplasticdeformationofthePLLA.HydroxyapatiteÓ2011ElsevierLtd.Allrightsreserved.Nanocomp
6、ositeMechanicalproperties1.Introductiondimensionsandcrystallinemorphology[17e23].Moreover,otherphysicalchangesmayresultfromprolongedexposuretoanaqueousPoly-L-lactide(PLLA)isasemicrystallinethermoplasticthatmedium,suchasphysicalageing,changesinthecrystallineiswidelyusedinbiomedicalapplications,owing
7、toitsexcellentmorphologyandplasticizationowingtowaterabsorption,whichbiocompatibilityandinherentbiodegradability[1e12].ItismayalsobeofcrucialimportancefortheperformanceofPLLAincurrentlyunderconsiderationfor
