Ph.D. thesis (pdf) - dirac

More documents

Recommendations

Info

$Guide to Imfufa LaTeX - dirac$

92 Alpha Relaxation correlation between stretching and fragility should be interpreted as a correlation between stretching and the isochoric fragility, while a correlation to isobaric fragility is an indirect consequence hereof. This means that the stretching is related to the “pure” effect of temperature on the relaxation time. This is consistent with the fact that the fragility and the stretching both stay constant on an isochrone. So far we have considered only fragility and stretching at the conventional glass transition temperature, that is around τ α = 100 s. However, the stretching depends on the relaxation time and also the departure from Arrhenius temperature dependence and hence the fragility depend on relaxation time (see sections 2.2 and 3.3.5). The general qualitative behavior is that the fragility decreases approaching the strong limit when the relaxation time is decreased and the “normal” liquid regime is approached. The decrease in relaxation time is also accompanied by a decrease in stretching (increase in β KWW ) and a Debye behavior is approached as the liquid regime is reached. This gives support to the idea that the intrinsic (isochoric) fragility of a liquid is correlated to the intrinsic stretching of the relaxation function. 5.4 Summary We report dielectric relaxation data under pressure for two molecular liquids, m- toluidine and DBP. We combine the relaxation time data with the available thermodynamic data and analyze the respective effect of density and temperature on the dynamics. This result is consistent with a general picture in which the isochoric fragility is constant on an isochrone. The shape of the relaxation function (eg. expressed by the stretching parameter β KWW ) is also found to be constant on an isochrone. We use the framework in chapter 3 in order to discuss effect of density on the possible correlation between the fragility and the stretching of the relaxation function. We suggest that if the stretching correlates to fragility then it should be correlated to isochoric rather than isobaric fragility.
Résumé du chapitre 6 Le facteur de structure cohérent a été mesuré dans le polyisobutylène pour différentes masses molaires et dans le cumène en fonction de la température à pression atmosphérique et à 300 MPa. Les expériences et les résultats sont présentés dans ce chapitre. L’effet principal de la pression est une augmentation du vitesse de son, tandis que son amortissement reste plus ou moins le même. Le facteur de non-ergodicité (rapport entre l’intensité élastique et l’intensité totale) mesuré dans les verres (en dessous de T g ) ne varie pas avec la pression. Cela implique une augmentation du paramètre α défini par Scopigno et al. [2003] du fait de la dépendance en pression de la température de transition vitreuse. Le paramètre α augmente aussi avec la masse molaire. L’évolution de α avec la pression comme celle avec masse molaire ne suivent pas l’évolution attendue du fait de la correlation entre α et la fragilité isobare. Sur la base du schéma developpé dans le chapitre trois, on discute l’effet respectif de la température et de la densité sur une corrélation possible entre α et la fragilité du liquide. On suggère que la grandeur à considérer dans le cadre d’une corrélation d log e(ρ) avec α n’est pas une fragilité mais la derivée d log ρ . C’est-à-dire que α est relié à l’effet de la densité sur le temps de relaxation plutôt qu’à l’effet de la température.
Page 1:
THÈSE présentée par Kristine NIS
Page 5 and 6:
Acknowledgement First of all I woul
Page 7 and 8:
Contents Abstract iii Acknowledgeme
Page 9:
CONTENTS ix 9 Summarizing discussio
Page 12 and 13:
2 Introduction fragility with other
Page 15:
Résumé du chapitre 2 De manière
Page 18 and 19:
8 Slow and fast dynamics glass. The
Page 20 and 21:
10 Slow and fast dynamics energy in
Page 22 and 23:
12 Slow and fast dynamics increasin
Page 24 and 25:
14 Slow and fast dynamics (linear)
Page 26 and 27:
16 Slow and fast dynamics The dynam
Page 28 and 29:
18 Slow and fast dynamics T > T 2
Page 30 and 31:
20 Slow and fast dynamics as theore
Page 32 and 33:
22 Slow and fast dynamics and sugge
Page 34 and 35:
24 Slow and fast dynamics The boson
Page 36 and 37:
26 Slow and fast dynamics modulus 3
Page 39 and 40:
Chapter 3 What we learn from pressu
Page 41 and 42:
3.2. Empirical scaling law and some
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
3.3. Correlations with fragility 37
Page 49 and 50:
3.4. Temperature dependences 39 mea
Page 51: 3.5. Summary 41 assumption that the
Page 55 and 56: Chapter 4 Experimental techniques a
Page 57 and 58: 4.2. Dielectric spectroscopy 47 4.1
Page 59 and 60: 4.2. Dielectric spectroscopy 49 fie
Page 61 and 62: 4.3. Inelastic Scattering Experimen
Page 79: Résumé du chapitre 5 La relaxatio
Page 82 and 83: 72 Alpha Relaxation the dielectric
Page 84 and 85: 74 Alpha Relaxation Measuring the c
Page 86 and 87: 76 Alpha Relaxation 4 2 0 This work
Page 88 and 89: 78 Alpha Relaxation for the 1 s iso
Page 90 and 91: 80 Alpha Relaxation log10(τ α ) 2
Page 92 and 93: 82 Alpha Relaxation 2 1 0 216.4K th
Page 94 and 95: 84 Alpha Relaxation function has a
Page 96 and 97: 86 Alpha Relaxation 2.5 2.5 2 2 log
Page 98 and 99: 88 Alpha Relaxation 0.4 log 10 Im(
Page 100 and 101: 90 Alpha Relaxation keeping the rel
Page 105 and 106: Chapter 6 High Q collective modes I
Page 107 and 108: 6.1. Inelastic X-ray scattering 97
Page 109 and 110: 6.2. Sound speed and attenuation 99
Page 115 and 116: 6.3. Nonergodicity factor 105 where
Page 117 and 118: 6.3. Nonergodicity factor 107 1 0.9
Page 119 and 120: 6.3. Nonergodicity factor 109 high
Page 121 and 122: 6.4. Nonergodicity factor and fragi
Page 127 and 128: 6.5. Summary 117 d log (e(ρ))/ d l
Page 129: Résumé du chapitre 7 Dans ce chap
Page 132 and 133: 122 Mean squared displacement colle
Page 134 and 135: 124 Mean squared displacement 1.5 I
Page 136 and 137: 126 Mean squared displacement 1.4 1
Page 138 and 139: 128 Mean squared displacement a cen
Page 140 and 141: 130 Mean squared displacement cumen
Page 142 and 143: 132 Mean squared displacement / a
Page 144 and 145: 134 Mean squared displacement I P i
Page 146 and 147: 136 Mean squared displacement as be
Page 149: Résumé du chapitre 8 Le pic de bo
Page 152 and 153:
142 Boson Peak The FEC-model sugges
Page 154 and 155:
144 Boson Peak the Qout Q in factor
Page 156 and 157:
146 Boson Peak We are mainly intere
Page 158 and 159:
148 Boson Peak 1.5 x 10−3 ω [meV
Page 160 and 161:
150 Boson Peak comparison of the ev
Page 162 and 163:
152 Boson Peak In figure 8.6 we sho
Page 164 and 165:
154 Boson Peak Predictions/explanat
Page 166 and 167:
156 Boson Peak meaning that the Deb
Page 168 and 169:
158 Boson Peak g(ω)/ω 2 [arb. uni
Page 170 and 171:
160 Boson Peak are equivalent becau
Page 172 and 173:
162 Boson Peak m P /m ρ 2 1.8 1.6
Page 174 and 175:
164 Boson Peak S(ω) [arb.unit] S(
Page 176 and 177:
166 Boson Peak 3 2.5 S(ω) [arb. un
Page 178 and 179:
168 Boson Peak perature effect on t
Page 181 and 182:
Chapter 9 Summarizing discussion Wh
Page 183 and 184:
173 temperature in the harmonic app
Page 185:
Chapter 10 Perspectives In this wor
Page 188 and 189:
178 BIBLIOGRAPHY Angell, C. A. [199
Page 190 and 191:
180 BIBLIOGRAPHY Casalini, R. and R
Page 192 and 193:
182 BIBLIOGRAPHY Farago, B., Arbe,
Page 194 and 195:
184 BIBLIOGRAPHY Inamura, Y., Arai,
Page 196 and 197:
186 BIBLIOGRAPHY Monaco, A., Chumak
Page 198 and 199:
188 BIBLIOGRAPHY Patkowski, A., Gap
Page 200 and 201:
190 BIBLIOGRAPHY Sekula, M., Pawlus
Page 203 and 204:
Appendix A Details on the samples T
Page 205 and 206:
A.1. Cumene 195 the value found fro
Page 207 and 208:
A.2. PIB 197 The temperature depend
Page 209 and 210:
A.4. DBP 199 peak differently at di
Page 211 and 212:
A.6. Other samples 201 NH 2 tempera
Page 213 and 214:
Appendix B Data compilations B.1 Da
Page 215 and 216:
B.1. Data compilation 205 DHIQ = De
Page 217 and 218:
B.1. Data compilation 207 Triphenyl
Page 219 and 220:
Appendix C Dielectric setup Figure
Page 222:
Abstract The degree of departure fr
show all

Ph.D. thesis (pdf) - dirac

Create successful ePaper yourself

Delete template?

Save as template?