Electrical Conductivity and Dielectric Behavior of Some Poly(Alkyl Methacrylate)s/Polyvinylpyrrolidone Blends

Abstract

A systematic dielectric study over a frequency range of 100 Hz up to 100 k Hz was carried out on some poly(alkyl methacrylate)s: poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(butyl methacrylate) (PBMA) blended with polyvinylpyrrolidone (PVP). The compatibility investigation, which was tested by using the dielectric method and confirmed by viscosity technique, led to a conclusion that both PMMA/PVP and PEMA/PVP blends are incompatible while PBMA/PVP blends are compatible. Tetrachlorophthalic anhydride (TCPA) was chosen to be added in increasing quantities (0%–30% by weight) to the investigated blends. Ten percent of such anhydride was found to solve the problem of phase separation between both incompatible blends. Moreover, the electrical conductivity of the investigated blends was found to increase linearly, in the semilogarithmic scale, by increasing TCPA content (10⁻¹² to 10⁻⁵ S⁻¹ cm⁻¹). After subtraction of the losses due to dc conductivity, the dielectric data reveal a lower frequency absorption region, which is found to be unchanged by increasing either the blend ratio or the content of TCPA. This region ascribes the Maxwell-Wagner effect due to the difference in the permittivity and conductivities in polymeric materials. The higher values of ϵ″ in the higher frequency range for all the blends indicates a higher frequency absorption region with maximum frequency out of the available range of frequencies. The addition of TCPA shifts this maximum towards lower frequencies. This shift indicates an increase in the molar volume of the rotating units and consequently an increase in the relaxation time.

Keywords:

• Dielectrics
• polymer blends
• compatibility