Electrical and thermal properties of carbon nanotubes/PMMA composites induced by low magnetic fields

Abstract

Ni particles supported on carbon nanotubes (CNTs) were dispersed in a polymethyl methacrylate (PMMA) matrix by solution blending and then cast onto an electrode to get composite films under low magnetic fields. The orientation of CNTs in the films was characterised by scanning electron microscope and optical microscope. Multimeter and high resistance meter were used to study the electrical behaviour of the nanocomposites. The glass transition temperature T g of PMMA was determined by differential scanning calorimetry. The results show that the alignment of the CNTs dispersed in the PMMA was achieved under a low magnetic strength below 0?5 T. Because of the ferromagnetism of Ni particles, the magnetic alignment of CNTs susceptibly changed. The magnetic alignment units in this work were rod-like CNTs aggregates instead of single CNTs, which took part in the buildup of a specific CNTs network structure in PMMA matrix. The network structure played a key role in significantly improving electrical conductivity and T g of the nanocomposites.

Effects of carbon nanotubes on polymer physics

“…Interestingly, the T g increase was twice as large for the sample with aligned tubes than for the sample without aligned tubes. 94 The increase in T g was even larger, from 2 C with no alignment to 12 C with alignment (above the value for epoxy with no nanotubes), for a 0.05 wt % MWCNT/epoxy composite cured in the presence of an AC electric field. 95 Finally, using prealigned nanotube forests (nanotubes that are grown vertically from a flat substrate) and infiltrating molten polystyrene led to a significant reduction in T g which was more pronounced the less complete the loading.…”

Functionalization of Carbon Nanotubes and Polymer Compatibility Studies

“…This great interest is due to the remarkable anisotropic properties that aligned CNTs cause on polymer matrices. Several methods for this purpose have been described in the literature, including: mechanical stretching, electro-spinning, wet spinning, weak magnetic fields (WMF) (Ma, Wang, & Yu, 2010), electrohydrodynamic (EHD) patterning (Goldberg-Oppenheimer, Eder, & Steiner, 2011), strong magnetic fields (SMF, Kimura et al, 2002), electrophoresis or electric field (Murugesh, Uthayanan, & Lekakou, 2010), and water-assisted chemical vapor (WACV) deposition (Zeng, Ci, Carey, Vajtai, & Ajayan, 2010).…”

Tailoring the properties of a polymer nanocomposite with a magnetic field

“…Therefore, the nanotubes must be first magnetized if realistic magnetic fields are to be employed , that is, by wrapping polymers functionalized with iron oxide nanoparticles . These nanoparticles can also be decorated with nickel, maghemite and magnetite nanoparticles and aligned under a relatively weak field . The decorations occur through chemical methods that destroy the CNT surfaces, do not improve their hydrophobicity, or increase their electrical contact resistance .…”