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network and the percolation threshold of PANI is achieved as seen by the conductivity value of 3.5×10 -7 S cm -1 . Although the percolation threshold is defined as a transition state and occurs at different conductivity values, typically its value is between 10 -11 S cm -1 and 10 -9 S cm -1 . The relatively high conductivity value of 3.5×10 -7 S cm -1 for sample (B) shows that percolation threshold has in fact been reached at a significantly lower concentration than 5% PANI. Sample (C) is a quinary blend containing 5% PANI comprised of HDPE/PS/PMMA/PVDF/PANI. This system attains an even higher conductivity value of 1.2×10 -6 S cm -1 thus corresponding to a lower percolation threshold due to the further geometrical restrictions imposed by the additional phase. Sample (D) represents a blend with five components and a di-block copolymer of adjacent PS and PMMA phases in the blend. Since the PS and PMMA phases are located beside each other, the addition of their copolymer to a blend results in the size of the PS and PMMA phases being decreased (compare Figures 4-13a and 4-13b). This reduction of size in the PS and PMMA phases carries over to other phases including PANI. The highest conductivity value for blend containing 5% PANI is obtained for sample (D) with a value of 4.2×10 -6 S cm -1 . The 5% percolation threshold value for PANI reported above is the lowest ever obtained in a melt processed multi-component system. Moreover, as discussed earlier, since the PANI sample used here is a mixture of 25% PANI and 75% zinc compound, the actual concentration of pure PANI at this percolation threshold value is less than 5%. Points (E), (F), and (G) represent ternary, quaternary, and five-component blends, each of which contains 10% PANI. Point (H) is a quaternary blend containing a copolymer of PS and PMMA. Although the extent of PANI is ten percent in these cases and higher conductivity values are obtained for blends compared to samples containing 5%, a similar behavior in increasing the conductivity value with multi-percolated samples is observed. Higher concentration of PANI in the samples containing 10% PANI results in more connected pathways of PANI in the sample yielding a higher conductivity range from 6.2×10 -11 S cm -1 for ternary to 2.2×10 -3 S cm -1 for the quaternary blend plus copolymer. Ternary, five-component, and six-component samples denoted as (I), (J), and (K), respectively, having 20% PANI are blended. Sample (I) shows a high conductive value of 2.2×10 -3 S cm -1 for the ternary blend indicating that although the PANI is encapsulated by the middle 130
phase(PMMA), the concentration of PANI is high enough (20 vol%) to create a random network inside the PMMA. This implies that at a high concentration of PANI, the effect of the morphology of the system on the conductivity is less important. At those higher concentrations, random connected pathways form in the system for all morphologies. But morphology is still affective whereas samples (J) and (K) comprising of more components represent higher conductivity values of 1.2×10 -3 S cm -1 and 4.5×10 -3 S cm -1 . Samples L and M in Figure 4-14 with 25% PANI demonstrate that 25% of PANI in the sample is sufficient to completely diminish the effect of morphology on conductivity and random networks of PANI form everywhere in the sample. Even at higher concentrations of PANI no significant increase in conductivity for the blend is observed as random pathways saturate the sample. Since the PANI concentration and morphology of the phases in these samples have no affect on the conductivity, even ternary(sample N) and binary(sample O) blends show the maximum conductivity and plateau behavior. 4.5 Conclusions We have used polyaniline as a conductive polymer to prepare a solid, 3D, low percolation threshold conductive device through the control of multiple encapsulation and multiple percolation effects in a 5 component PE/PS/PMMA/PVDF/PANI polymer blend system through melt processing. The percolation threshold in the multi-component polymer blend is shown to be sensitive to the morphological continuity of the various encapsulated phase networks. PANI is situated in the core of the multiple network system due to its high surface tension and polarity and, in this way its percolation threshold can be reduced to less than 5%. The detailed morphology and continuity diagrams of binary, ternary, quaternary and finally quinary systems are progressively studied in order to systematically demonstrate the concentration regimes resulting in the formation of these novel multiple-encapsulated morphological structures. First, an onion-type morphology of HDPE/PS/PMMA/PVDF is prepared which is comprised of an HDPE matrix with a multiple-component polymeric droplet phase consisting of a PS shell, a PMMA middle layer and PVDF in the core. The order of phases in this concentrically organized onion morphology is thermodynamically controlled and is described by Harkins spreading 131
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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)
Page 125 and 126: polyanion such as hyaluronan (HA)(P
Page 127 and 128: 2.4.1.1.7 Effect of Salt on Multila
Page 129 and 130: 2.4.1.1.8 Overcompensation of the M
Page 131 and 132: important factors determining the g
Page 133 and 134: As shown in Figure 2-44, swelling a
Page 135 and 136: increasing the pH value due to a de
Page 137 and 138: CHAPTER 3 - ORGANIZATION OF THE ART
Page 139 and 140: discussed above, HDPE, PS, PMMA, an
Page 141 and 142: CHAPTER 4 - LOW PERCOLATION THRESHO
Page 143 and 144: or model which predicts where the p
Page 145 and 146: concentration threshold for the ons
Page 147 and 148: chemical and weathering resistance,
Page 149 and 150: Table 4-1. Material Characteristics
Page 151 and 152: filled with blend pellets. To facil
Page 153 and 154: 4.3.6 Conductivity Measurements DC
Page 155 and 156: experimentally in this research gro
Page 157 and 158: a) b) c) d) Figure 4-4. Schematic i
Page 159 and 160: microstructure of the quaternary bl
Page 161 and 162: a) b) c) d) Figure 4-6. SEM microgr
Page 163 and 164: a) b) PVDF PS PMMA c) d) e) HDPE PS
Page 165 and 166: Uniform layers of PS and PMMA situa
Page 167 and 168: the concentration of HDPE is increa
Page 169 and 170: a) b) c) e) Figure 4-11. SEM microg
Page 171 and 172: melt-processable and contains 25 wt
Page 173 and 174: One question that should be address
Page 175: Conductivity(S/cm) Ternary Blend 1,
Page 179 and 180: (6) Virgilio, N.; Desjardins, P.; L
Page 181 and 182: ONION MORPHOLOGY HDPE PVDF PS Contr
Page 183 and 184: work described above has focused on
Page 185 and 186: thermodynamic explanation to predic
Page 187 and 188: four-point probe increases continuo
Page 189 and 190: in the rheology tests were compress
Page 191 and 192: 5.3.6 Layer-by-Layer Deposition The
Page 193 and 194: prepare a polymer blend structure w
Page 195 and 196: a) b) c) Figure 5-3. Scanning elect
Page 197 and 198: spontaneously self-assembled. After
Page 199 and 200: 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,
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6.3.5.2 Focused Ion Beam (FIB) and
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a) c) b) d) e) f) PMMA PMMA HDPE HD
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y Harkins theory, PS will always si
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a) b) c) d) e) f) PS Figure 6-6. a)
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a) b) HDPE : black PS : grey PMMA :
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6.4.6 Continuity, Co-continuity, an
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c) V III II I VII I IV VI Figure 6-
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Continuity Scheme (a) Figure 6-10.
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Addition of a low concentration of
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Addition of small amounts of HDPE t
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icontinuous network with the HDPE.
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Three examples are shown in Figure
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(9) Mekhilef, N.; Verhoogt, H. Poly
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structures are formed due to the co
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CONCLUSION AND RECOMMENDATIONS In t
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REFERENCES A. K. Gupta, K. R. S. (1
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Caruso, F. (2003). Hollow Inorganic
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Domenech, S. C., Bortoluzzi, J. H.,
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Geuskens, G., Gielens, J. L., Geshe
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Hou, S., Harrell, C. C., Trofin, L.
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Krass, H., Papastavrou, G., & Kurth
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Macdiarmid, A. G., Jin-Chih, C., Ha
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Niziol, J., & Laska, J. (1999). Con
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Reghu, M., Yoon, C. O., Yang, C. Y.
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Shirakawa, H., Louis, E. L., MacDia
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Utracki, L. A. (1991). On the visco
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Yasuda, K., Armstrong, R., & Cohen,
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literature has examined factors inf
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(Reignier & Favis, 2000, 2003a; Rei
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Table A-1.2. Interfacial tensions a
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acquisition of images with a very h
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Table A-1.3. Continuity of the PMMA
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(17) Reignier, J.; Favis, B. D., Ma
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PANI. Theoretically, the extent of
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Equation A-2.7 0( ) 0 1. 5 σ = σ
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Cumulative Mass × 10 5 (g) dipping
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of PANI, and an increase in the con
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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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