Investigating the Suitability of Carbon Nanotube Reinforced Polymer in Transcatheter Valve Applications

Figure 1. Microscopy images of the nanotubes; typical SEM images of the (a) low (5000×) and (b) high aspect ratio (25,000×) nanotubes in their raw powder forms, and respective images close up at 20,000× and 100,000× magnification. Typical AFM topography images of (c) 0.5% and (d) 1.0% w/w low aspect nanotubes in PC3595A polyurethane. Black arrows highlight nanotubes imbedded within the polymer matrix.

Figure 2. Typical Raman spectra of low and high aspect ratio nanotubes showing the positions of the D, G and G′ bands.

Figure 3. Representative bright-field microscopy images of the distribution of nanotubes within the polymer matrix in (a) 0%, (b) 0.125%, (c) 0.5%, and (d) 1.0% w/w composites. Scale bars represent 20 µm.

Figure 4. Typical stress–strain curves exhibited in Carbothane® PC3595A with increasing nanotube concentration from 0.125 to 1.0% w/w.

Figure 5. Mean secant modulus against the dispersion time (hours) in an ultrasonic bath for 0.5 and 1.0% composites (n = 5). Error bars represent ± SE.

Figure 6. (a) Secant Modulus at 5% strain of 0 and 1.0% composites after immersion in distilled water for several days (n = 5). (b) Sample thickness (µm) with increasing time immersed in water (n = 6). Error bars represent ± SE.

Figure 7. Elastic modulus between 0.5 and 1.0 MPa stress with increasing strain rate and nanotube content (n > 4).

Figure 8. Results of the sterilization tests—secant modulus at 5% strain for the (a) neat, 0% and (b) composite 1.0% films and percentage stress relaxation for the (c) neat, 0% and (d) composite 1.0% films several days following gamma sterilization. Error bars represent ± SE.

Figure 9. Dip coated, reinforced polymeric heart valves with (a) 0%, (b) 0.125%, (c) 0.5%, and (d) 1.0% nanotube concentrations.