Nylon 6.6 accelerating aging studies II. Long-term therm al-oxidative.pdf

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1、PolymerDegradationandStability95(2010)1471e1479ContentslistsavailableatScienceDirectPolymerDegradationandStabilityjournalhomepage:www.elsevier.com/locate/polydegstabNylon6.6acceleratingagingstudies:II.Long-termthermal-oxidativeandhydrolysisresultsR.Bernstein*,K.T.GillenSandiaNationalLaboratories,

2、OrganicMaterialsDepartment,Albuquerque,NM87185-0888,USAarticleinfoabstractArticlehistory:Long-term(greaterthan5yearexposures),low-temperature(aslowas37C)acceleratedovenagingReceived23November2009resultswereobtainedforNylon6.6fibersunderthermo-oxidativeconditions(airagingwithanoxygenReceivedinrevi

3、sedformpartialpressureof13.2cmHginAlbuquerque).Toassesstheimportanceofhumidityonaging,experi-14June2010mentswerealsoconductedunderacombinationof100%RHplus13.2cmHgofoxygenpartialpressureatAccepted22June2010temperaturesrangingfrom138Cto64Cplusanadditionalexperimentat70%RHand80C.Thelow-Availableo

4、nline30June2010temperaturetensilestrengthresultsshowedthattheArrheniusactivationenergyunderthepureoxidativedegradationconditionsdroppedfromw96kJ/molabovew100Cew30kJ/molbelowthisKeywords:temperature,indicativeofatransitionintheoxidativechemistryatlowtemperatures.EarlierworkbyNylonHumidityourgroup

5、onthesamematerialconcludedthathydrolyticdegradationeffectsdominatedoxidationThermal-oxidativeeffectsathigheragingtemperatures.However,thecurrentlong-term,low-temperaturecomparisonsArrheniusevaluationleadtotheconclusionthathumidityisnotanimportantagingfactorbeloww50C.ByextrapolatingFieldagingtime

6、etemperaturesuperposedoxidativedegradationdatausingthelow-temperatureactivationenergy,Tensilestudiesweobtainpredictionsat21C.Atthistemperature,weestimatethatatensilestrengthlossof50%takesontheorderof70years.The21Cpredictionsareshowntobereasonablyconsistentwithlong-term(upto38year)ambientresults

7、onsimilarNylonmaterialsremovedfromfield-agedparachutes.Althoughtheestimatedaverageexposuretemperaturevariesfromparachutetoparachute,thehighestaveragetemperatureisestimatedtobeontheorderof21C.Ó2010ElsevierLtd.Allrightsr