Carbon nanotubes as nanofillers

Outline I II Polymer microcomposites filled with microparticles I.1 Mechanical melt blends I.2 Importance of « polymer/filler » interface (tension and adhesion) I.3 "Polymerization-filled composites" PFC's Polymer nanocomposites filled with nanoparticles II.1 Layered silicate as nanofillers - Polymer-clay nanocomposites : melt blending vs in situ polymerization - Polyolefinic matrices : role of matrices and compatibility - Polyester matrices : role of clays and organo-modification II.2 Carbon nanotubes as nanofillers - Polymer-CNTs composites : production and properties - « Melt blending » technique, e.g., in elastomeric matrices - in situ polymerization, e.g., in thermoplastic matrices III General conclusions et outlook Chapter : Polymer nanocomposites filled with nanoparticles Part II Carbon nanotubes as nanofillers Allotropic forms of Carbon Curl, Kroto, Smalley 1985 graphene Iijima 1991 (From R Smalley´s web image gallery) Carbon Nanotubes - Single-wall nanotubes (SWNTs) ~ 1-2 nm Few microns - Multi-wall nanotubes (MWNTs) TEM images of various MWNTs ~ - 50 nm Properties of CNT • Electrical : – High electric conductivity (higher than copper) – Easy process for Conductive Semi-conductive • Thermal : ‘Kink CNT’: divide conductive and semi-conductive – High thermal conductivity (higher than silicon) – Stable at high temperature • Physical : – 100 times stronger than steel but very light – Elastic behavior (Pressing CNT tip bend and recover to its original state) • Chemical : – Rarely react with other compounds – Chemically stable (a) (b) (c) Conductive Semiconductive Diode Synthesis methods of CNT • Arc discharge – – – First CNT synthesis method used by Dr.Iijima Arc is formed in the gap between two graphite electrodes Grow SWNT with catalyst (Co, Ni, Fe, Y, etc.), while MWNT without catalyst metal – Usual conditions : • 400~700 torr (use He gas) • 20~30 V between electrodes • 1mm distance between electrodes • 50~100 A – For higher purity: • Rotate cathode to uniform the arc • High the temperature • Use Hydrogen gas instead Helium gas Synthesis methods of CNT (cont’) • Laser vaporization – First used Smalley Group in 1995 – Use He or Ar gas and maintain 500 torr – Use laser, vaporize graphite Synthesis methods of CNT (cont’) CVD (Chemical vapor deposition) – Advantages : temperature, the insert gas, pressure, gas flow, catalyst, etc – Insert hydrocarbon gas (C2H2, C2H4, CH4, etc) into quartz tube and obtain Energy  insert gas decomposed and CNT grow on a quartz boat surface – Energy source categorizes CVD : thermal CVD, Hot filament plasma CVD, Microwave plasma CVD, RF plasma CVD, etc Synthesis methods of CNT (cont’) • CVD – – Thermal CVD – – – uses C2H2 gas and Ni, Fe, Co or all together as a catalyst Implementation is easy Grow large uniform CNT at high temperature (over 800 oC) Use mixture of Pd and Ni for substrate to maintain the high temperature condition  can grow high purity CNT vertically under 600o C Interest of carbon nanotubes as nanofillers  Electrical properties : Electronic components, sensors,…  Mechanic properties : high tenacity Tensile strength (GPa) Carbon nanotubes Tenacity Carbon fibers HDPE : 0.023 GPa Reinforcement of polymeric matrix (nano)composites  Thermal properties : « stability » and flame retardant behavior ... Part II Carbon nanotubes as nanofillers Allotropic forms of Carbon Curl, Kroto, Smalley 1985 graphene Iijima 1991 (From R Smalley´s web image gallery) Carbon Nanotubes - Single-wall nanotubes. .. Interest of carbon nanotubes as nanofillers  Electrical properties : Electronic components, sensors,…  Mechanic properties : high tenacity Tensile strength (GPa) Carbon nanotubes Tenacity Carbon. .. CVD, Hot filament plasma CVD, Microwave plasma CVD, RF plasma CVD, etc Synthesis methods of CNT (cont’) • CVD – – Thermal CVD – – – uses C2H2 gas and Ni, Fe, Co or all together as a catalyst Implementation