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the percolation threshold. As compared in Figures 2-20a and 2-20b, by using high aspect ratio fillers such as conductive fibers/wires, the conductivity of the polymer composite can be achieved at a much lower filler loading level (Figure 2-20c). Carbon-black particles are more irregularly shaped and often have long branches reaching out from the main body of the particle. These moderately structured fillers can require anywhere from 5 to 35% loading to reach the percolation threshold(Sichel, 1982). In carbon black filled nitrile rubber composite, the percolation threshold lies in between 20% and 35%, while for a short carbon fiber filled composite it ranges from 10% to 20%(Pramanik, Khastgir, & Saha, 1992). Highly shaped fillers such as carbon or stainless-steel fibers may be present in as little as a few percent by volume in order to achieve low resistance. Gelves et al.(Gelves, Lin, Sundararaj, & Haber, 2006) used silver and copper nanowires with a diameter of 25 nm and aspect ratios of up to 200 and 400, respectively. Electrical percolation thresholds of 0.5-0.75 vol.% for silver nanowires and 0.25-0.75 vol.% for copper nanowires in PS nanocomposites were found. Figure 2-20. Schematic illustrations of conductivity establishment for polymer composites with (a) spherical fillers, (b) high aspect ratio fillers (fiber/wire) and (c) percolation threshold (Vc) in a resistivity vs. filler loading plot(Wong, 2003-2008) Lin et al.(Lin, Gelves, Haber, Potschke, & Sundararaj, 2008) reported an electrical percolation threshold between 1 and 2 vol.% for polystyrene/copper nanowire nanocomposites. The nanowires have a diameter of around 25 nm and an average length of 1.29±0.83 μm. A very low percolation threshold of high aspect ratio fillers for silver nanotubes is shown in Figure 2-21. 50
Figure 2-21. Transmission electron micrograph of silver nanowires(Wong, 2003-2008) • Polymer Polarity Some studies(Miyasaka et al., 1982a) revealed that the polymer polarity may be related to the percolation threshold; that is the higher the polarity of a given polymer, the larger the percolation threshold is. As well, a correlation between the surface tension of the polymer and the percolation threshold was found(Johnson, Kendall, & Roberts, 1971): the larger the surface tension, the larger is the percolation threshold. • Polymer Viscosity Percolation threshold is limited by increasing the viscosity of the polymer(Sau, Chaki, & Khastgir, 1997), since high viscosity of the polymer results in high amount of breakdown and degradation of the structure of carbon black owing to the high shearing action experienced during mixing. Consequently, the formation of a conductive network throughout the matrix is delayed and occurs at a higher concentration(Sau, Chaki, & Khastgir, 1998). • Polymer Crystallization High-density polyethylene loaded with conductive carbon black showed that the carbon black aggregates tend to concentrate in amorphous regions. A major part of the carbon black aggregates in a semi-crystalline system are located in amorphous regions. Lower percolation 51
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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
Page 45 and 46: PS-co-PMMA copolymer of PS and PMMA
Page 47 and 48: 1.1 Introduction CHAPTER 1 - INTROD
Page 49 and 50: Figure 1-2. Human heart, longitudin
Page 51 and 52: One of the applications for porous
Page 53 and 54: On the other hand, a novel tri-cont
Page 55 and 56: 2.1 Polymer Blends CHAPTER 2 - LITE
Page 57 and 58: Based on Sterling’s approximation
Page 59 and 60: Antonoff’s rule (Equation 2-13) i
Page 61 and 62: 2.1.2.1 Binary Polymer Blends 2.1.2
Page 63 and 64: Some other studies(Everaert, Aerts,
Page 65 and 66: where the parameter z is dependent
Page 67 and 68: “compatibilization” was suggest
Page 69 and 70: a) λ BC A and B are matrices, b) C
Page 71 and 72: Reignier & Favis, 2000, 2003a; Reig
Page 73 and 74: measure the interfacial tension of
Page 75 and 76: a) b) Figure 2-6. Dependence of the
Page 77 and 78: Omonov et al. found double percolat
Page 79 and 80: 2.1.2.2.3 Effect of Composition on
Page 81 and 82: a) b) C B A c) Figure 2-12. SEM pho
Page 83 and 84: In the case where PS is the matrix,
Page 85 and 86: Posthuma de Boer, 1999) (Kumin & Ch
Page 87 and 88: lattice, such as square lattice, wi
Page 89 and 90: magnetization, which is a function
Page 91 and 92: Polymers have long been thought of
Page 93 and 94: epoxy as a function of nanotube wei
Page 95: Figure 2-19. Approaching the percol
Page 99 and 100: Figure 2-22: Dependence of PE conti
Page 101 and 102: Figure 2-24. Plot of the total numb
Page 103 and 104: chain provides the conductive path
Page 105 and 106: 2.3.1.2.1 Polyaniline One of the mo
Page 107 and 108: CoPA/LLDPE/PANI blend and a poor-qu
Page 109 and 110: Narkis and co-workers extended and
Page 111 and 112: Figure 2-31: Conductivity of PVDF/P
Page 113 and 114: organic thin films, a novel and str
Page 115 and 116: on the topic have been reported in
Page 117 and 118: succeeded in creating thin films wi
Page 119 and 120: Addition of salt to the solution of
Page 121 and 122: different from that of linear homop
Page 123 and 124: 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
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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.
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Since the ultra-low surface area va
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c) a) b) Figure 5-6. a),b) Scanning
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salt to a PSS polyelectrolyte solut
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A relationship between macropore si
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close together. It is interesting t
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Figure 5-9. Mass increase (%) indic
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In this work the conductance of the
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deposited PANI layers increases unt
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(52) Guo, H. F.; Packirisamy, S.; G
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6.2 Introduction It is well-known t
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modified version of Harkins theory(
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6.3 Experimental 6.3.1 Materials Co
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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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