DIELECTRIC ANALYSIS OF THE BREAKUP OF LIQUID-CRYSTALLINE POLYMER FIBERS IN A THERMOPLASTIC MATRIX

In this paper we discuss the use of dielectric spectroscopy as a means to study the morphology of polymer blends. We have investigated a mod el system of thermotropic liquid crystalline polymer (Vectra B950) fib ers lined up in a polypropylene (Stamylan P 13E10) matrix. The appeara nce of interfacial polarization at the interface between the two polym eric phases makes it possible to calculate the shape of the inclusions . For this purpose a formula is derived, which gives the shape factor of a distorted fiber as a function of the distortion amplitude. The ca lculated shapes of the fibers agree very well with the actual shapes, despite the approximations made. The agreement was proven by performin g dielectric measurements under an optical microscope. As expected, th e growth rate of thick fibers is smaller than that of thinner ones. A comparison between experiments under the microscope and in a dielectri c sample holder showed the importance of the heating rate on the break up of the fibers.