Dispersion and confinement of multiwall carbon nanotubes in immiscible polymer blends

A wide spectrum of applications of carbon nanotubes (CNTs) in specific engineering applications includes high performance materials in space applications, automotive applications, electronic devices, electromagnetic shielding (EMI) and electrostatic dissipative (ESD) materials. High L/D ratio and flexibility along with attractive forces between multiwall carbon nanotubes (MWNTs) surfaces manifest in highly ‘agglomerated’ structure of ‘as-received’ MWNTs. Incorporation of MWNTs in various polymer matrices has been exploited as a strategy to obtain electrically conducting composites with superior mechanical and thermal properties. CNTs pose issues during processing with polymer matrices, arising from ‘agglomeration’ and ‘entanglement’ of MWNTs, ‘slippage’ of nanotubes during deformation and, poor polymer/MWNTs interfacial interaction. It is therefore a challenging task to achieve a uniform dispersion of MWNTs in a polymer matrix through melt-mixing technique. In order to uniformly disperse MWNTs in immiscible polymer blends, it is necessary to enhance the extent of ‘debundling’ of MWNTs and selectively localize the MWNTs in one of the phases or at the interface. It is difficult to determine the state of dispersion of MWNTs in polymer matrices using a single characterization technique. Hence, the investigation of dispersion has been carried out at various length scales in order to study the overall state of dispersion of MWNTs in the polymer blend of polyamide 6 (PA6) and acrylonitrile butadiene styrene copolymer (ABS) with the help of novel organic non-covalent modifiers in combination with a suitable reactive compatibilizer. Thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy of the Indian Institute of Technology Bombay, India and Monash University, Australia.