Anisotropic thermal conductivity of polypropylene composites filled with carbon fibers and multiwall carbon nanotubes

Abstract

Polypropylene‐based composites filled with carbon fibers and multiwall carbon nanotubes were produced by coagulation precipitation technique. Composite articles were produced by conventional injection molding technique. It was shown that the addition of carbon nanotubes (10% of total amount of carbon fibers) results in significantly increased anisotropic thermal conductivity of the composite due to formation of thermal conductive bridges between carbon fibers, which are oriented during molding. The addition of CNTs has a significant effect with more than a 50–70% increase of both the axial and transverse thermal conductivity of the composite. Produced composites were used for injection molding of polymeric radiators for LED lamps, showing sufficient heat dissipation efficiency allowing using them for industrial application in the field. POLYM. COMPOS., 36:1951–1957, 2015. © 2014 Society of Plastics Engineer

The relevance of material and processing parameters on the thermal conductivity of thermoplastic composites

“…The damage to the nanotubes because of the functionalization process might also play part in the TC lowering. This bridge-formation effect is seen in many combinations of CNTs with the second filler [41][42][43][44][45] and shows great promise for improving the TC of polymer composites. The CNTs also seem to be severely less affected by polymer flow, thus show less orientation in the flow direction after processing [44].…”

The roles of interphase and filler dimensions in the properties of tunneling spaces between CNT in polymer nanocomposites

“…Polymer carbon nanotube (CNT) nanocomposites can be applied in many fields such as electronics, aerospace, and sensing, due to the excellent performances of CNT including high‐electrical conductivity and exceptional mechanical properties . The growing level of studies on polymer CNT nanocomposites confirms this claim.…”

Tailoring the properties of a polymer nanocomposite with a magnetic field

“…Including 1 wt% of multiwall carbon nanotubes (MWNTs) in polyvinyl alcohol increases the elastic modulus and hardness of the resulting composite by 80% and 60%, respectively . Composites with aligned CNTs exhibit higher electric and thermal conductivities than those that contain randomly dispersed CNTs and, as expected, this enhancement is a function of the nanomaterial weight content . The percolation threshold for CNTs in a typical polymer lies within 0.5 wt%, and is influenced by several factors, such as degree of alignment, dispersion homogeneity, polymer type, and processing method .…”

“…The alignment of CNTs along particular directions in a polymer matrix can be accomplished by applying external electric and magnetic fields , by injection molding or by leveraging the fluid drag force on the nanoparticles as they are being dispersed in the uncured matrix . Since CNTs have a poor magnetic susceptibility, this necessitates the application of a relatively strong external magnetic field during alignment to produce a force that exceeds the thermal energy and viscous resistance of the uncured polymer .…”