Strong, Tough, Electrospun Polymer–Nanotube Composite Membranes with Extremely Low Density

Abstract

Electrospinning has been used to produce porous, low density, polymer–nanotube composite membranes. The membrane mechanical properties can be enhanced by tuning the nanotube content, aligning the fibers during spinning, and by post production drawing. The mechanical properties are maximized for membranes with a nanotube content of 0.43 vol %. Aligned composites at this volume fraction have been prepared by spinning onto a rotating drum collector electrode. This method results in significant increases in modulus, strength, and toughness. The best composites, produced at the maximum drum rotation rate, were post treated by a drawing step to result in further increases in modulus and strength. These methods allows the production of membranes with densities as low as ∼340 kg m−3 but with values of stiffness, strengths and toughness's more typically found in bulk thermoplastics; 1.2 GPa, 40 MPa, and 13 J g−1.

Mechanical properties of individual electrospun polymer-nanotube composite nanofibers

“…In addition, to calculate the modulus we resort to assuming purely brittle failure, a significant simplification. We can test the validity of these assumptions fairly simply by noting that, for a range of reported PVA-nanotube composites (7,18,30), the strength scales linearly with the modulus ( B =0.04E) as shown in Figure 4. For comparison, we plot the calculated strength versus the calculated modulus for our fibers in Figure 4.…”

“…Watersoluble PABS-SWCNTs (www.carbonsolution.com) were chosen to achieve high-quality nanotube dispersions in the PVA/water solutions (7,16). A concentration of 250gL -1 of PVA was used to prepare PVA/PABS-SWCNTs solutions with various mass fractions of SWCNTs (from 1 wt% down to 0.06wt%).…”

“…In recent years, a number of papers have appeared demonstrating the strength of polyvinylalcohol (PVA)-nanotube fibers (18,20) and films (23,24). In addition, surprisingly strong electrospun membranes have been produced from PVA (7).…”

“…For many of these applications, mechanical strength and toughness are extremely important as even partial failure could have catastrophic consequences. While the topological properties of the network have a significant influence on its mechanical properties (7), the strength of the membrane is ultimately limited by the strength of the individual fibers. As such, significant work has gone into reinforcing the individual fibers through the incorporation of carbon nanotubes (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Carbon Nanotubes Reinforced Electrospun Polymer Nanofibres

“…The tensile strength of these membranes increased from 5.8 MPa to 12.9 MPa by adding 1wt% of MWNTs. In a recent study, however, Blond et al [155] achieved a higher level of reinforcement. They produced aligned SWNT/PVA nanofibre membrane with the strength of up to 40 MPa using a rotating drum collector followed by mechanical stretching.…”