Plasma‐modified CNFs, GPs, and their mixtures for enhanced polypropylene thermal conductivity

Abstract

Low thermal conductivity of polypropylene (PP) is a key factor in limiting its use for the manufacture of solar heaters. To overcome this problem, in the present work, two different methods were tested to increase the thermal conductivity of a PP matrix by increasing the dispersion and compatibility between PP and carbon nanoparticles (CNPs). In the first method, CNPs modified superficially by plasma of propylene were used, and in the second, mixtures of CNPs (carbon nanofibers and graphene platelets in 9:1, 8:2, and 7:3 ratios) were used. Dispersion and compatibility between PP and CNPs were tested by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The results show that both methodologies increase the dispersion and compatibility and, therefore, the thermal conductivity of the PP matrix (0.14 W m−1 K−1), which reached up 0.90 W m−1 K−1. It was also observed that dispersion is a key factor in high concentrations (5 wt/wt%) of CNPs to obtain high thermal conductivity and compatibility in low concentrations (1 wt/wt%). Finally, only a synergistic effect was observed at 1 wt/wt% when using surface‐modified CNPs by plasma and at 5 wt/wt% when the CNPs were used without surface treatment.

Matching micro‐ and nano‐boron nitride hybrid fillers for high‐thermal conductive composites

“…[12][13][14][15][16][17][18][19][20] Fundamentally, these micro/nanofillers could enhance the polymer's TC via forming continuous thermal conductive pathways in composites. 21,22 Some studies reported that the filler's size and content significantly influenced the formation of thermal conductive networks. 23,24 On the one hand, the fillers with larger sizes benefited for lower thermal interfacial resistances and higher TCs, due to their fewer contact interfaces.…”

“…To solve this problem, many researchers have fabricated polymer composites by incorporating micro/nanofillers with high TCs into the polymer matrix, such as metal particles, 7,8 graphene nanosheets, 9,10 carbon nanotubes, 11 and boron nitride nanosheets (BNNs) 12–20 . Fundamentally, these micro/nanofillers could enhance the polymer's TC via forming continuous thermal conductive pathways in composites 21,22 . Some studies reported that the filler's size and content significantly influenced the formation of thermal conductive networks 23,24 .…”

Enhancement of polypropylene mechanical behavior by the synergistic effect of mixtures of carbon nanofibers and graphene nanoplatelets modified with cold propylene plasma

“…On the contrary, CNPs [P], load transfer with the polymer occurs through van der Waals or π-interactions, weaker than the hydrogen and covalent bonding presented by CNPs [M]. 53,54 The differences mentioned above in compatibility were also studied by Raman analysis in a previous study (Covarrubias et al 15 ); the compatibility was related to the intensity of the 2D band associated with tangential vibrations (carbons with sp 2 hybridization). The signal of the tangential vibrations related to carbon atoms with sp 2 hybridization dissipated when the surface of the CNPs interacted with the PP matrix.…”

“…4,14 It is well known that surface treatments of the CNPs can increase compatibility. [15][16][17][18][19] However, the most modification methods require long periods of exposure of the CNPs to chemical substances that are aggressive with the surface and have solventassociated problems, such as environmental problems and solvent disposal costs. From an industrial point of view, where mass production is a priority, these approaches lead to substantial economic and environmental issues.…”

“…Although significant advances have been demonstrated in the area, 11–13 two main factors limited the application of polymeric nanocomposites with CNPs: The poor compatibility of CNPs in polymeric matrices limits the potential improvements of polymer composites 4,14 . It is well known that surface treatments of the CNPs can increase compatibility 15–19 . However, the most modification methods require long periods of exposure of the CNPs to chemical substances that are aggressive with the surface and have solvent‐associated problems, such as environmental problems and solvent disposal costs.…”