Dielectric parameters of polymers and monomers of the vinyl series in the microwave range

Abstract

The production of polymeric materials is one of the fast-growing sectors in the chemical industry. Improving methods for synthesizing high-molecular compounds and studying their physicochemical characteristics are important tasks of synthetic chemistry. Radical polymerization is currently the main method for producing polymeric materials. Its advantages involve simplicity and low cost, along with the possibility of obtaining a wide range of polymeric materials. The results of measuring the dielectric parameters of various high-molecular compounds (polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, poly(glycidyl methacrylate)) in the frequency range of 100–200 GHz (refractive index and dielectric loss tangent tgδ) are presented. The compounds under study were both those synthesized by radical polymerization with the participation of the conventional initiator, i.e., azobisisobutyric acid dinitrile, and commercial products. The absorption capacity of polymers at room temperature was compared. Polymers with the highest and lowest absorption capacity were determined. The dependence of tgδ on frequency for all the polymers under study is linear, with absorption in the polymers increasing with frequency. Poly(glycidyl methacrylate) exhibits the highest absorption among the studied macromolecules with tgδ being equal to 0.043 at 200 GHz. The minimum tgδ value of 0.0068 was found for polystyrene. For the polymers under study, the refractive index value varies in the range from 1.09 to 1.39. In addition, dielectric properties of the original vinyl monomers (styrene, vinyl acetate, glycidyl methacrylate) were studied. The results are of interest when developing approaches to obtaining polymeric materials with specified characteristics based on vinyl monomers by the method of radical polymerization.