Medium density polyethylene composites with functionalized carbon nanotubes

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• A strong interface between single-walled carbon nanotubes (SWNTs) and polymer matrices is crucial for improving composite mechanical properties.
• Sidewall functionalization of SWNTs is explored to enhance interfacial chemistry and mechanical performance.

Purpose of the Study:

• To evaluate the effect of sidewall functionalization on SWNT aspect ratio and composite interfacial chemistry.
• To determine the role of functionalized SWNTs in enhancing the mechanical properties of medium density polyethylene (MDPE) composites.

Main Methods:

• Synthesis of fluorinated SWNT derivatives (F-SWNTs) and a perfluorinated derivative (F-SWNT-C(11)F(x)H(y)).
• Integration of pristine and functionalized SWNTs into an MDPE matrix at 1 wt% loading.
• Characterization using FTIR, Raman, NMR, XPS, AFM, SEM, TGA, DSC, and tensile tests.

Main Results:

• The perfluorinated derivative, F-SWNT-C(11)F(x)H(y), resulted in a 52% enhancement in tensile strength compared to neat MDPE.
• SWNTs with higher aspect ratios in the 1 wt% SWNT/MDPE composite showed less mechanical improvement due to poor interfacial chemistry.
• Fluorinated SWNT derivatives demonstrated superior mechanical enhancement in the MDPE matrix.

Conclusions:

• Sidewall functionalization, particularly perfluorination, is key to achieving strong interfacial adhesion between SWNTs and MDPE.
• Optimized interfacial chemistry in SWNT-polymer composites leads to significant improvements in mechanical properties.
• The study highlights the potential of tailored SWNT functionalization for advanced composite materials.