Abstract
Polymer nanocomposite materials of higher thermal and electrical transport properties are important to nanotechnology applications such as thermal management, packaging, labelling and the textile industry. In this work, thermal and electrical conductivities in nanocomposites of multiwalled carbon nanotubes (MWCNT) and isotactic polypropylene (iPP) are investigated in terms of MWCNT loading, temperature dependence, and anisotropy caused by melt shearing. IPP/MWCNT nanocomposites show a significant increase in thermal and electrical conductivity with increasing MWCNT loading, reaching 17.5 W/m K and 10−6 S/m, respectively, at a MWCNT 5.0 weight percentage at 40°C. The increase in MWCNT/iPP is more than would be expected based on the additivity rule, and suggests a reduction of the interfacial thermal electrical resistance at nanotube-nanotube junctions and the nanotube-matrix interface. The anisotropy in both conductivities was observed to be larger at low temperature and to disappear at higher temperature due to isotropic electrical and thermal contact in both directions. Oriented MWCNT/iPP nanocomposites exhibit higher electrical and thermal conductivities, attributed primarily by orientation of nanotubes due to the shearing fabrication process.
Highlights
The modern history of human technology has been defined by the replacing of machines with suitable materials which can perform functions more efficiently and without much maintenance
The isotactic polypro‐ pylene (iPP) polymer was added to the xylene containing the multi-wall carbon nanotubes (MWCNT) to form different weight percent‐ age concentrations of MWCNTs in the nanocomposites for the study
Our results suggest that alternative nanocomposite fabrication and processing methods that combine the effect of aligning a matrix and higher MWCNT loadings are likely to exhibit higher electrical conductivities with broader percolation threshold
Summary
The modern history of human technology has been defined by the replacing of machines with suitable materials which can perform functions more efficiently and without much maintenance. Composite materials have continuously been substituted with nano-engineered and adapted polymer nanocomposite materials. Carbon nanotubes have been considered as ideal additive fillers for composite materials to improve both electrical and thermal transport properties. Experimental and theoretical work has shown a significantly high thermal conductivity with 3000 W/m K for multi-wall carbon nanotubes (MWCNT) [1,2]. Polymers have low thermal and electrical conductivities due to restriction of the phonon/electron motion through the composite matrix, and have larger interfacial thermal/electrical resistances at the polymernanotube interfacial surface [4, 11,12]
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