The Piezoelectric, Electric, and Dielectric Properties of Amorphous Polyimide Polymers

1. The Piezoelectric, Electric, and Dielectric Properties of Amorphous Polyimide Polymers A research investigation by Paul Paris and Dr. Joseph Ficht under the direct supervision of Dr. Zoubeida Ounaies

2. Project One Synopsis • To investigate the effect of carbon nanotubes (CNT’s) in terms of content and method of processing, on the piezoelectric, electric, and dielectric properties of an amorphous piezoelectric polyimide polymer.

3. Project Two Synopsis • To investigate the effect of carbon nanofibers (CNF’s) and carbon nanotubes (CNT’s) on the mechanical, electrical, and dielectric properties of PVDF

7. What is an Amorphous Polymer? • A polymer with randomly oriented molecules that are intertwined like cooked spaghetti • The polymer has a glasslike, transparent appearance • Examples: • Polystyrene-hard and rigid plastic at room temperature • Polyethyl Acrylate- soft, flexible rubbery material at room temperature

8. Electroactivity E l’<l

9. What Is Piezoelectricity? Actuator function: Sensor function: Force • Requires dipole orientation • Dipoles collectively respond to field • due to remnant polarization • Sensing and actuation capability Piezoelectricity

10. What is a Polyimide ? • A polymer of imide monmers that in conjunction with the carbon nanotubes, produce a composite that has excellent physical, electrical, and mechanical properties • Light weight and flexible • Multilayer insulators • Resistance to harsh space environment • Good support structures Structure of bCN(APB/ODPA), Polyimide

11. What is Polyvinyl Difluoride? Polyvinyl Difluoride (PVDF) is a polymer comprised of hydrogen, carbon, and fluorine atoms. It is a polar substance as the hydrogen atoms lose electrons to the fluorine atoms. In 1969 it was first observed that this polar or dipole nature could be used to generate piezoelectricty.

12. Single Walled Carbon Nanotube (SWNT) What is a Carbon Nanotube? • A thin layer of graphene rolled into a seamless tube and capped at both ends • Electrical, Thermal, and Mechanical properties of graphite help to improve electrical conductivity, thus enhancing the structural composition of the polymer

13. Health monitoring Flow sensors and actuators Smart Ski (ACX) What are some applications? • NASA Applications • Electro-optical Device Technologies • Precise positioning • Switches • Multifunctional Membranes • Antennas • Reflectors • Smart skins • Tuning and positioning inflatable structures • Biomedical • Portable Artificial organs • lightweight fetal heart monitor • Ultrasonic imaging • Tissue engineering Inflatable Antennae Ultrasonic imaging

14. Experimental Details • SEM images to investigate dispersion of CNT’s • Electrode samples for electrical and dielectric measurements • Measurement comparison using thermally stimulated current measurements (TSC) • Dielectric and electrical properties as a function of frequency at room temperature before and after poling • Pole at a single voltage; time; temperature

15. SEM Results of BCN SWNT .05wt% BCN SWNT Samples

16. SEM Results of PVDF+ DWNT

17. Results of Dielectric Constant Testing on Polyimide

18. Results of Dielectric Testing on PVDF

19. Results of Dielectric Testing on PVDF (Continued)

20. Results of Adding CNF and DWNT to PVDF • Pure PVDF is an insulator but adding carbon nanofibers increased the dielectric constant and conductivity. Adding the double walled nanotubes, however, greatly increased the dielectric constant and conductivity and now shows the characteristics of a conductor.

21. QUESTIONS?