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4.3.5 Characterization of Phase Morphology 4.3.5.1 Microtoming and Scanning Electron Microscopy (SEM) The specimens were cut and microtomed to a plane face under liquid nitrogen using a microtome (Leica-Jung RM 2065) equipped with a glass knife and a cryochamber type (LN 21). After the appropriate chemical treatment at room temperature with selective solvents (acetic acid for PMMA, cyclohexane for PS, chromic acid for PANI, and DMF for all three of PVDF, PMMA, and PS) to remove one or several of the components, the sample surface was coated with a gold/palladium by plasma deposition. A JEOL JSM 840 scanning electron microscope, operated at a voltage of 10 keV to 12 keV, was used to obtain photomicrographs of the sample surface. 4.3.5.2 Focused Ion Beam (FIB), Atomic Force Microscopy (AFM) A FIB/AFM technique was used to examine the PE/PS/PMMA blend. After cryomicrotoming of the specimens using a glass knife to obtain perfectly flat surface, samples were coated with a gold-palladium alloy. The surface of the samples was then treated and etched using a Hitachi focused ion beam FIB-2000A operated at 30 keV gallium beam. FIB uses a focused beam of gallium ions which are accelerated to energy of 5-50 kiloelectronvolts. Using an electrostatic lens, ion beam can be focused on a very small spot, resulting in a high resolution because of the small emitting area. In this work, a 0.8 nA beam current and a dwell time at 3 μs was applied in order to remove approximately 3-4 μm of the surface. Milling was carried out parallel to the observed surface. Since each polymer component has a different interaction with the gallium beam, this approach induces topological differences and hence increases the contrast between components. The milled surface of the specimen was then examined by a scanning probe microscope dimension (AFM) with a Nanoscope IIIa controlled in topological mode. The atomic force microscope measures topography with a force probe. Silicon tips with spring constant of 40 N/m and a resonant frequency of around 300 kHz was employed. 106
4.3.6 Conductivity Measurements DC electrical measurements were performed through the vertical thickness of the substrate at ambient temperatures using a Keithley electrometer model 6517. The sample is placed between two sample holders and a DC voltage is applied using two point probe equipment. The setup works at a voltage range of 0-1000V and an ammeter range of 0-20mA. To standardize equal pressure for all samples, a 5lb load was applied on the sample holders. Cylindrical specimens with a thickness of 1.2mm and a radius of 1.25cm were tested in dry air. Although the top and bottom surfaces of the samples are flat, two graphite sheets covered the surface of the sample in order to ensure good contact of the sample surface and electrodes. The electrical conductivity of the samples varied over a wide range from 10 -12 S cm -1 to 10 -1 S cm -1 . The average % error in the conductivity measurements is ± 0.2 orders of magnitude. 4.4 Results and Discussions 4.4.1 Reducing the Percolation Threshold of PANI in a Multi-component Polymer Blend The principal objective of this work is to control the morphology of a multi-component polymer blend in order to significantly reduce the percolation threshold of the conductive PANI component. The first question to be addressed is where does the PANI need to be located in the blend system? In recent work, Zhang et al.(J. Zhang, et al., 2007) demonstrated that the percolation threshold of one component could be reduced to values as low as three percent by preparing a ternary blend and situating that phase at the interface of two other co-continuous phases. In Figure 4-3a, it is shown that polystyrene situates at the interface of PE and PMMA and the ordering of the phases can be directly related to Harkins spreading theory. In Figure 4-3a, the identification of the phases can be clearly seen by the topographical heights induced by FIB etching and subsequently quantified by AFM analysis in the topographical mode. Previous work showed that PMMA is 107
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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
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
Page 147 and 148: chemical and weathering resistance,
Page 149 and 150: Table 4-1. Material Characteristics
Page 151: filled with blend pellets. To facil
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 and 176: Conductivity(S/cm) Ternary Blend 1,
Page 177 and 178: phase(PMMA), the concentration of P
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
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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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