Alignment of multi-wall carbon nanotubes by disentanglement in ultra-thin melt-drawn polymer films

• Published in: Carbon (New York) Vol. 60; pp. 366 - 378
• Main Authors: Arras, Matthias M.L., Schillai, Christoph, Keller, Thomas F., Schulze, Robert, Jandt, Klaus D.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2013; Elsevier
• Subjects: Alignment; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Lead (metal); Materials science; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanotubes; Physics; Polyethylenes; Polymer matrix composites; Polymeric films; Polypropylenes; Transmission electron microscopy; Carbon nanotubes; Films; Polymers; Melts
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2013.04.049

Aligned multi-wall carbon nanotube (MWCNT)/polymer composite films were created in a one-step process. 5wt% MWCNT/semi-crystalline polymer composite films of approximately 100nm thickness were obtained by melt-drawing. The matrix polymers were isotactic polypropylene (iPP), poly(1-butene) (PB-1) and high density polyethylene (HDPE). Transmission electron microscopy (TEM) investigations revealed an exceptionally high degree of local MWCNT alignment with an angular deviation of <10° (HDPE) and <20° (iPP and PB-1) parallel to the films’ drawing direction for a broad range of drawing velocities. For HDPE, the lamellar polymer-crystals at the interface between the MWCNT and the polymer film were identified as the nano-hybrid shish-kebab morphology by selected area electron diffraction. Based on the direct visualization of the MWCNT disentanglement process in the TEM, a polymer physics-based model for the unraveling of MWCNT entanglements, a source of aligned MWCNTs, is proposed that explains differences in MWCNT alignment encountered for different matrix polymers. The melt-drawing mediated MWCNT alignment provides both an innovative approach for the fabrication of applicable MWCNT containing films and a versatile tool for studying the interface in MWCNT/polymer composites.