ABSTRACT
ThecharacterizationoftheinitialstateofPDMSadsorptiononfumedsilicaprovidesamethodfortheanalysisofsilica-watermoleculeinteractions.Inthissection, itisshownthattightlyboundwatermoleculesarenotreleasedfromthesilica surfaceduringthemechanicalmixing.Thisfeatureconcernsthespecificamount
Q~,measuredrightaftertheendofthemechanicalmixingandaftereliminating freechains;Q~hasbeenfoundtovaryasthesquarerootofthechainmolecular weightaccordingtotheequation
ThelinearvariationofthefractionofboundrubberQ~/QiisdepictedinFig.2;Qi istheinitialamountofpolymerpergramofsilicainthemixture.Sucharesult
(g/g)
FIG.2Fractionofboundpolymer.Purepolymer;specificsurfacearea:300m2jg (Ill),150m2 jg(0),and50m2 jg(A)(thescaleofM~/2 /Qiwasdividedby3).x: bimodalpolymer(specificarea:50m2 jg;thescaleofM~ 1 /2 /Qiwasdividedby3). CurveA,fractionmeasuredrightafterthemechanicalmixingofPDMSwithsilica. CurveB,fractionmeasuredatequilibrium.
