BNGR-HASS
Propriétés à l’Ambiante de Polymères Amorphes Greffés UDETA
Analytical methods
Différentiel scanning calorimetry (DSC) DSC measurements havebeenperformedon1015mgsampleswithaDSCQ1000 fromTA instrumentsequippedwithaliquidnitrogencoolingsystem.Anitrogenandargon flowwasused, theT4modewasselected.Theglasstransitiontemperaturesweremeasured from+10°C/min temperature ramps.
Solvent resistance
The solvent resistance tests were carried outwit various solvents in which the samples were immersed.Four Possible Results Can Be Observed: i)the sample is unchanged after immersion for along time, ii)thesamplekeepsthesameroughshape, the dimensions are increased, iii)a hazy solution is obtained and the sample has disappeared, iv)aclear solutionisobtainedandnopieceofthesampleisremaining.Wecanthusconcludethat : i) the sample is not soluble in this solvent, ii) the sample is swollen by the solvent, it is sensitivetothesolventbutnotsolubleinit, iii)the polymer is not completely soluble in the solvent,iv)the samples completely dissolved,it is soluble in the solvent.
Dynamic mechanical analysis (DMA)
DMAmeasurementswere carried out using a 2980DMAfromTAinstruments equippedwithaliquidnitrogencoolingsystem.Theelastic(E’)andviscous(E”) flexural modulus were recorded from 2 °C/min temperature ramps, using a single cantilever geometry.
Creep tests Creep experiments were carried out in aDMA2980 in the single cantilever geometry.Thetemperaturewassetat10°CbelowTgofthestudiedmaterial.Aftertheset 136 ChapitreIV–Propriétésàl’AmbaintedePolymèresAmorphesGreffésUDETA temperature hasbeen reached,apreloadforceof0.01N was applied during5minutes.The stresswasthenrapidlyincreasedto10MPa,thedisplacementoftheextremityofthesample was recordedasa functionof time.Thestresswas releasedafter2hoursanda2hours recoverywasmonitored. In The Special caseofPMMA3,which is very brittle, sometests wereperformedata1MPaload.
Three-point bending tests ADMA2980 operating in the three point bending geometry was used for three point bending tests. The temperature was set at 30°C. After the temperature has been reached, afiveminutesequilibriumtimehasbeenapplied.Thecentralpartof thesample wasthendisplacedwithaloadrateof+4N/min.
Stress cracking measurements Stresscrackingexperimentsweredonetostudythecombinedinfluenceofsolvent andmechanical stress onPMMAsamples. The stress relaxation, andcrazes andcracks formationwere examined.A homemadethree point b endingapparatusbasedonaroutine rheometerwasused.Theminimumlengthofthesamplesis24.25mm(distancebetweenthe twoouter cylindersof thisgeometry).The appliedforceand de formation were monitored using anARES (Rheometric Scientific) straincontrolled rheometer. Five pictures per minutewererecordedthroughavideocameralinkedtoacomputerequippedwithLynxRT
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