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CHAPTER 7 - GENERAL DISCUSSIONS AND PERSPECTIVE In the previous chapters, it was shown that a hierarchically ordered, interfacial tension driven morphology can be assembled. In this multiple-percolated structure, thermodynamic properties can determine the number of interfaces between phases(the number of contacts between phases). In the next perspective of the work the influence of viscous forces on the morphology by changing the shape and size of the phases can be studied. For example, by increasing the shear stress in a bi-continuous/dispersed phase morphology, the size of the droplets should be decreased due to the increasing breakup rate as compared to coalescence. Moreover, due to the higher shear force, the shape of the droplets may also become more elongated. Therefore, changing the applied shear stress on the system would be expected to result mostly in the variation of the size and shape of the phases. Changing the hierarchical order of phases in the blend, which depends significantly on the thermodynamic properties of the system, is almost impossible. It is well-known that the third factor affecting the morphology of multi-component blends is the composition of phases. This factor affects the morphology by imposing a geometrical restriction between phases and controls the rate of breakup and coalescence. At high concentration of one phase the droplets of that phase coalesce further with each other and therefore the rate of coalescence increases until a continuous structure is constructed. For blends comprised of more than three components, composition can also play a role in the prediction of the phase morphology. Thermodynamics plays another role in the morphology of ternary blends through the governing Harkins equation and the prediction of three-phase contact and two-phase contact morphologies as mentioned in detail in chapter 6. In both cases of complete and partial wetting, a high interfacial tension between phases results in a decrease of the interfacial area between them leading to larger phase sizes. All the effects of these three parameters(composition, interfacial tension, and shear stress) are schematically shown for a complete wetting case of a ternary blend in Figures 7-1 and 7-2. Figures 7-1 and 7-2 illustrate various morphologies of a blend with a matrix of phase (A) depending on the interfacial tension of B/C and the composition of phases B and C at low shear rate and high shear rate, respectively. It is shown that at low concentration of minor phases, a matrix/core-shell morphology is observed. At higher concentration of minor phases, tri-continuous and bi-continuous/dispersed 206
structures are formed due to the coalescence of droplets. At low interfacial tension of B/C the interfacial area between these phases increases and small droplets of phase (C) are dispersed in phase (B). For the case of a high interfacial tension of B/C, the droplets coalesce with each other and large droplets or a continuous structure of that phase is observed. Finally the effect of shear rate is shown and at low shear rate, the shape of the phases are more regular and the phase sizes are larger due to the higher capillary number. At high shear rate, the structures become more elongated and the number of composite droplets and continuous islands increase due to the smaller size of the phases. Interfacial Tension Composition Equation 7-1. Dependence of the morphology of a ternary blend demonstrating complete wetting on the interfacial tension of B and C and as a function of the composition of Phases B and C at low shear rate. Note that in the schematics, yellow represents phase (A) which is the matrix, blue represents phase (B) and green represents phase (C). 207
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© Sepehr Ravati, 2010. UNIVERSITÉ
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DEDICATED To my parents iii
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RÉSUMÉ Cette thèse présente, po
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devenir une structure hiérarchique
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ABSTRACT This thesis presents, for
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system can be increased from 10 -15
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CONDENSÉ EN FRANÇAIS Dans ce trav
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deuxième coquille de PS. Les phase
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structures à percolation multiple
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autre sous-type de morphologie dans
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TABLE OF CONTENTS DEDICATION.......
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xxiii 2.4.1.1.1 Charged Polymer Ads
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5.3.4 Annealing Test ..............
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xxvii REFERENCES ..................
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LIST OF FIGURES xxix Figure 1-1. a)
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Figure 2-12. SEM photomicrograph of
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Figure 2-34. Schematic view of diff
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Figure 4-8. SEM micrographs of vari
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Figure 5-6. a),b) Scanning electron
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and c) triangular concentration dia
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n number of moles p concentration o
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AFM atomic force microscopy LIST OF
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PS-co-PMMA copolymer of PS and PMMA
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1.1 Introduction CHAPTER 1 - INTROD
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Figure 1-2. Human heart, longitudin
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One of the applications for porous
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On the other hand, a novel tri-cont
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2.1 Polymer Blends CHAPTER 2 - LITE
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Based on Sterling’s approximation
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Antonoff’s rule (Equation 2-13) i
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2.1.2.1 Binary Polymer Blends 2.1.2
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Some other studies(Everaert, Aerts,
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where the parameter z is dependent
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“compatibilization” was suggest
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a) λ BC A and B are matrices, b) C
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Reignier & Favis, 2000, 2003a; Reig
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measure the interfacial tension of
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a) b) Figure 2-6. Dependence of the
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Omonov et al. found double percolat
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2.1.2.2.3 Effect of Composition on
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a) b) C B A c) Figure 2-12. SEM pho
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In the case where PS is the matrix,
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Posthuma de Boer, 1999) (Kumin & Ch
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lattice, such as square lattice, wi
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magnetization, which is a function
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Polymers have long been thought of
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epoxy as a function of nanotube wei
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Figure 2-19. Approaching the percol
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Figure 2-21. Transmission electron
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Figure 2-22: Dependence of PE conti
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Figure 2-24. Plot of the total numb
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chain provides the conductive path
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2.3.1.2.1 Polyaniline One of the mo
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CoPA/LLDPE/PANI blend and a poor-qu
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Narkis and co-workers extended and
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Figure 2-31: Conductivity of PVDF/P
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organic thin films, a novel and str
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on the topic have been reported in
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succeeded in creating thin films wi
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Addition of salt to the solution of
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different from that of linear homop
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Figure 2-39. Macromolecule with a)
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polyanion such as hyaluronan (HA)(P
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2.4.1.1.7 Effect of Salt on Multila
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2.4.1.1.8 Overcompensation of the M
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important factors determining the g
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As shown in Figure 2-44, swelling a
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increasing the pH value due to a de
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CHAPTER 3 - ORGANIZATION OF THE ART
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discussed above, HDPE, PS, PMMA, an
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CHAPTER 4 - LOW PERCOLATION THRESHO
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or model which predicts where the p
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concentration threshold for the ons
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chemical and weathering resistance,
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Table 4-1. Material Characteristics
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filled with blend pellets. To facil
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4.3.6 Conductivity Measurements DC
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experimentally in this research gro
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a) b) c) d) Figure 4-4. Schematic i
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microstructure of the quaternary bl
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a) b) c) d) Figure 4-6. SEM microgr
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a) b) PVDF PS PMMA c) d) e) HDPE PS
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Uniform layers of PS and PMMA situa
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the concentration of HDPE is increa
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a) b) c) e) Figure 4-11. SEM microg
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melt-processable and contains 25 wt
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One question that should be address
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Conductivity(S/cm) Ternary Blend 1,
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phase(PMMA), the concentration of P
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(6) Virgilio, N.; Desjardins, P.; L
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ONION MORPHOLOGY HDPE PVDF PS Contr
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work described above has focused on
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thermodynamic explanation to predic
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four-point probe increases continuo
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in the rheology tests were compress
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5.3.6 Layer-by-Layer Deposition The
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prepare a polymer blend structure w
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a) b) c) Figure 5-3. Scanning elect
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spontaneously self-assembled. After
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a) b) c) d) e) f) g) h) Figure 5-5.
Page 201 and 202: Since the ultra-low surface area va
Page 203 and 204: c) a) b) Figure 5-6. a),b) Scanning
Page 205 and 206: salt to a PSS polyelectrolyte solut
Page 207 and 208: A relationship between macropore si
Page 209 and 210: close together. It is interesting t
Page 211 and 212: Figure 5-9. Mass increase (%) indic
Page 213 and 214: In this work the conductance of the
Page 215 and 216: deposited PANI layers increases unt
Page 217 and 218: (52) Guo, H. F.; Packirisamy, S.; G
Page 219 and 220: 6.2 Introduction It is well-known t
Page 221 and 222: modified version of Harkins theory(
Page 223 and 224: 6.3 Experimental 6.3.1 Materials Co
Page 225 and 226: Complex voscosity (Pa.s) 1,0E+04 1,
Page 227 and 228: 6.3.5.2 Focused Ion Beam (FIB) and
Page 229 and 230: a) c) b) d) e) f) PMMA PMMA HDPE HD
Page 231 and 232: y Harkins theory, PS will always si
Page 233 and 234: a) b) c) d) e) f) PS Figure 6-6. a)
Page 235 and 236: a) b) HDPE : black PS : grey PMMA :
Page 237 and 238: 6.4.6 Continuity, Co-continuity, an
Page 239 and 240: c) V III II I VII I IV VI Figure 6-
Page 241 and 242: Continuity Scheme (a) Figure 6-10.
Page 243 and 244: Addition of a low concentration of
Page 245 and 246: Addition of small amounts of HDPE t
Page 247 and 248: icontinuous network with the HDPE.
Page 249 and 250: Three examples are shown in Figure
Page 251: (9) Mekhilef, N.; Verhoogt, H. Poly
Page 255 and 256: CONCLUSION AND RECOMMENDATIONS In t
Page 257 and 258: REFERENCES A. K. Gupta, K. R. S. (1
Page 259 and 260: Caruso, F. (2003). Hollow Inorganic
Page 261 and 262: Domenech, S. C., Bortoluzzi, J. H.,
Page 263 and 264: Geuskens, G., Gielens, J. L., Geshe
Page 265 and 266: Hou, S., Harrell, C. C., Trofin, L.
Page 267 and 268: Krass, H., Papastavrou, G., & Kurth
Page 269 and 270: Macdiarmid, A. G., Jin-Chih, C., Ha
Page 271 and 272: Niziol, J., & Laska, J. (1999). Con
Page 273 and 274: Reghu, M., Yoon, C. O., Yang, C. Y.
Page 275 and 276: Shirakawa, H., Louis, E. L., MacDia
Page 277 and 278: Utracki, L. A. (1991). On the visco
Page 279 and 280: Yasuda, K., Armstrong, R., & Cohen,
Page 281 and 282: literature has examined factors inf
Page 283 and 284: (Reignier & Favis, 2000, 2003a; Rei
Page 285 and 286: Table A-1.2. Interfacial tensions a
Page 287 and 288: acquisition of images with a very h
Page 289 and 290: Table A-1.3. Continuity of the PMMA
Page 291 and 292: (17) Reignier, J.; Favis, B. D., Ma
Page 293 and 294: PANI. Theoretically, the extent of
Page 295 and 296: Equation A-2.7 0( ) 0 1. 5 σ = σ
Page 297 and 298: Cumulative Mass × 10 5 (g) dipping
Page 299 and 300: of PANI, and an increase in the con
Page 301 and 302: Resistance(ohm) 1.0E+12 1.0E+11 1.0
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esistance value. Samples containing
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The results of resistance for PS/PE
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Caruso, F., & Schuler, C. (2000). E
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