RESUMEN

In this work, the charge dynamics characteristics of injection, transport and decay in porous and non-porous polytetrafluoroethylene (PTFE) film electrets were investigated by means of corona charging, isothermal and thermal stimulating surface-potential decay measurements. The results showed that the initial surface potential, whether positively or negatively charging, is much higher in non-porous PTFE than in porous PTFE. For porous film the value of initial surface potentials increases with increase of film thickness. Higher charging temperature can remarkably improve charge stability. The charge dynamics are correlated to materials microstructure according to their scanning electron micrographs. For non-porous PTFE films, polarizability change of C-F bonds is the main origin of electret charges; but for porous PTFE film a large number of bulk and interface type traps are expected because of the greater area of interface and higher crystallinity.

Asunto(s)

RESUMEN

The relation between the orientational stability and molecule structure in the molecule dipole polymer electret with second-order optical nonlinearities was studied by means of IR and UV spectra. The effect of the solvents on the structure was discussed when the materials were prepared. The results showed that dipole moment orientation would damaged the conjugate pi system of the chromophore dipole molecule when the specimen was poled around the glass transition temperature. The Cis-Trans photoisomerization and thermal isomerization of azobenzene group was main reason that caused the dipole orientational relaxation. The used solvents when the specimen were prepared will affect material structure and consequently affect the nonlinear optics stability of molecular dipole polymer electrets.