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Optimization of Buckypaper-enhanced Multifunctional Thermoplastic Composites

View Article: PubMed Central - PubMed

ABSTRACT

A series of flattened-nanotube reinforced thermoplastic composites are sizably fabricated as a function of buckypaper loading. The effects of the volume fraction, nanotube alignment and length on the tensile performance of the composites are factored into a general expression. The incorporation of self-reinforcing polyphenylene resin (Parmax) into a highly aligned buckypaper frame at an optimal weight ratio boosts the tensile strength and Young’s modulus of the buckypaper/Parmax composite to 1145 MPa and 150 GPa, respectively, far exceeding those of Parmax and aligned buckypaper individually. The composite also exhibits improved thermal (>65 W/m-K) and electrical (~700 S/cm) conductivities, as well as high thermoelectric power (22 μV/K) at room temperature. Meanwhile, the composite displays a heterogeneously complex structure. The hexyl groups of Parmax noncovalently interact with the honeycomb structure of the flattened nanotube through π-stacking and CH-π interaction, correspondingly improving the dispersity of polymer on the nanotube surface and the interfacial stress transferring while the high alignment degrees of nanotube facilitate phonon and charge transport in the composites.

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The temperature dependence of thermal conductivity (a), electrical conductivity (b) and Seebeck Coefficients (c) of the buckypaper/Parmax composites with different carbon nanotube content. The thermal and electric properties of the 65%-stretched buckypaper are also included for comparison.
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f2: The temperature dependence of thermal conductivity (a), electrical conductivity (b) and Seebeck Coefficients (c) of the buckypaper/Parmax composites with different carbon nanotube content. The thermal and electric properties of the 65%-stretched buckypaper are also included for comparison.

Mentions: CNTs are excellent filler for the fabrication of conductive nanocomposites thanks to their high charge mobility and high aspect ratio. The dispersion and alignment of MWNTs in the polymer matrix directly determine the electrical properties of the polymer composites16. As seen in Fig. 2a, the electric conductivity (σ) of the buckypaper/Parmax composites along with 65%-stretched buckypaper strip shows a positive temperature dependence (dσ/dT > 0), showing a non-metallic behavior. The mechanisms of the charge carrier transport in the buckypaper network are mainly the fluctuation-assisted tunneling through barriers and the variable-range hopping between mesoscopic metallic islands of conducting tubes separated by insulating ones17. Parmax is an insulator with an electrical conductivity of approximately 10−13 S/cm. The electrical conductivity is dramatically enhanced by the incorporation of buckypaper. When 45 wt% CNT is added to the Parmax (45BPmx), the conductivity increases to 78.7 S/cm, improved approximately 14 orders of magnitude compared to that of the neat Parmax. For the composite 60BPmx, the conductivity climbs to 698.5 S/cm, significantly higher than that of the composites containing low CNT content by using the regular mixing dispersion approach18. These high conductivities are attributed to the MWNT alignment and the dense packing of MWNT buckypaper, leading to better contacts among the nanotubes. The electric conductivity of the neat 65%-stretched buckypaper sample can reach 1032.3 S/cm.


Optimization of Buckypaper-enhanced Multifunctional Thermoplastic Composites
The temperature dependence of thermal conductivity (a), electrical conductivity (b) and Seebeck Coefficients (c) of the buckypaper/Parmax composites with different carbon nanotube content. The thermal and electric properties of the 65%-stretched buckypaper are also included for comparison.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5304317&req=5

f2: The temperature dependence of thermal conductivity (a), electrical conductivity (b) and Seebeck Coefficients (c) of the buckypaper/Parmax composites with different carbon nanotube content. The thermal and electric properties of the 65%-stretched buckypaper are also included for comparison.
Mentions: CNTs are excellent filler for the fabrication of conductive nanocomposites thanks to their high charge mobility and high aspect ratio. The dispersion and alignment of MWNTs in the polymer matrix directly determine the electrical properties of the polymer composites16. As seen in Fig. 2a, the electric conductivity (σ) of the buckypaper/Parmax composites along with 65%-stretched buckypaper strip shows a positive temperature dependence (dσ/dT > 0), showing a non-metallic behavior. The mechanisms of the charge carrier transport in the buckypaper network are mainly the fluctuation-assisted tunneling through barriers and the variable-range hopping between mesoscopic metallic islands of conducting tubes separated by insulating ones17. Parmax is an insulator with an electrical conductivity of approximately 10−13 S/cm. The electrical conductivity is dramatically enhanced by the incorporation of buckypaper. When 45 wt% CNT is added to the Parmax (45BPmx), the conductivity increases to 78.7 S/cm, improved approximately 14 orders of magnitude compared to that of the neat Parmax. For the composite 60BPmx, the conductivity climbs to 698.5 S/cm, significantly higher than that of the composites containing low CNT content by using the regular mixing dispersion approach18. These high conductivities are attributed to the MWNT alignment and the dense packing of MWNT buckypaper, leading to better contacts among the nanotubes. The electric conductivity of the neat 65%-stretched buckypaper sample can reach 1032.3 S/cm.

View Article: PubMed Central - PubMed

ABSTRACT

A series of flattened-nanotube reinforced thermoplastic composites are sizably fabricated as a function of buckypaper loading. The effects of the volume fraction, nanotube alignment and length on the tensile performance of the composites are factored into a general expression. The incorporation of self-reinforcing polyphenylene resin (Parmax) into a highly aligned buckypaper frame at an optimal weight ratio boosts the tensile strength and Young’s modulus of the buckypaper/Parmax composite to 1145 MPa and 150 GPa, respectively, far exceeding those of Parmax and aligned buckypaper individually. The composite also exhibits improved thermal (>65 W/m-K) and electrical (~700 S/cm) conductivities, as well as high thermoelectric power (22 μV/K) at room temperature. Meanwhile, the composite displays a heterogeneously complex structure. The hexyl groups of Parmax noncovalently interact with the honeycomb structure of the flattened nanotube through π-stacking and CH-π interaction, correspondingly improving the dispersity of polymer on the nanotube surface and the interfacial stress transferring while the high alignment degrees of nanotube facilitate phonon and charge transport in the composites.

No MeSH data available.


Related in: MedlinePlus