Polyimides are presently being investigated for a wide range of aeronautic, aerospace and industrial applications
due to the fact that they have good thermal and chemical resistance yet are flexible. Within the realm
of aerospace applications, polyimides can be employed for deployment, positioning, and vibration attenuation
of large structures including thin-film membrane mirrors and gossamer antennas. The inclusion of single wall
carbon nanotubes raises the conductivity levels to permit electric discharge. Additionally, they augment the
electromechanical coupling properties of piezoelectric polyimides to provide them with actuator capabilities. We
present a temperature-dependent material model based on elasticity theory which characterizes stiffness through
the material as a function of varying concentrations of single wall nanotubes (SWNT). We begin by investigating
the temperature affects on the polyimide. We then discuss the effects of SWNT volume concentration on the
composite storage modulus. The composite model takes into account the alignment, interphase, and geometry
of the SWNTs.
Cellulose Electro-Active Paper (EAPap) has potential as a smart material due to its advantages of biodegradability,
lightweight, air actuation, large displacement output, low actuation voltage and low power consumption. However,
improvement of its small output force and low actuating frequency band still remain as drawbacks. In this study,
asymmetrical arrangement of Multi-Walled Carbon Nanotubes (MWNTs) in cellulose matrix was investigated to resolve
drawbacks. Corona discharging technique was used by means of DC electrophoresis of MWNTs in cellulose matrix. To
make MWNTs mixed cellulose EAPap, cellulose fibers were well dissolved in 8%(w/w) LiCl/DMAc (N,N-dimethyl
acetamide) by swelling procedure followed by solvent exchange technique. MWNTs were well dispersed in the cellulose
solution by sonication for 2 hours, and the suspension was spin-coated on an ITO (Indium tin oxide) coated glass, and
high DC electric field was given to the spincoated suspension for 3 hours at 40°C. The structure of MWNT/Cellulose
film was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and
X-ray diffraction (XRD). It was seen that most of MWNTs were moved and biased toward cathode, and film having
double layer-like structure was made.
Electrospinning of a SWNT-polyimide composite is accomplished under DC electric field. The resulting composite fibers are characterized to assess the alignment of the SWNTs in the polyimide. Polarized Raman spectroscopy is performed using a Nicolet dispersive Raman spectrometer with a polarizer. The Raman spectrum of SWNT-polyimide fibers is recorded at several angles between the SWNT axis and the incident polarization, in the range of 0° to 180°. The Raman peak in each spectrum corresponds to the tangential mode (1590 cm-1) of the SWNT in the composite. Inspection of the spectra reveals that the maximum intensity is obtained when the polarization of incident radiation is parallel to the SWNT axis, while the smallest intensity is obtained when the polarization of incident radiation is perpendicular to the SWNT axis. Difference in the intensities when the radiation is parallel and perpendicular to the SWNT axis indicates preferential alignment of SWNTs in the polyimide fibers.
Single wall carbon nanotube (SWNT)-polymer composites aligned by an AC electric field were characterized using Raman spectroscopy and electrical conductivity measurements to assess the resulting alignment. The Polarized Raman spectra was recorded at several angles between the SWNT axis and the incident polarization ranging from 0° to 180°. Inspection of the spectra revealed that maximum intensity is obtained when the polarization of incident radiation is parallel to the SWNT axis (0° and 180°), while the smallest intensity is obtained when the polarization of incident radiation is perpendicular to the SWNT axis (90°). The electrical measurements were made in three directions; parallel to the aligned SWNTs and perpendicular to the aligned SWNTs. Based on the electrical conductivity and polarized Raman spectroscopy measurements, it can be concluded that the SWNTs in the polymer matrix were preferentially aligned by applying an AC electric field of 43.5 V/mm at a frequency of 1 Hz, 10 Hz, 10 KHz and 100 KHz.