Microwave absorbing polymer composites

The authors have synthesized the thermally stable epoxy resin modified polymer composites such as polydiphenylamine, benzidine polyvinyl alcohol, styrene polymethyl methacrylate by in situ polymerization technique. To this, the materials were modified with triethylene tetramine as hardener to obtain highly cross-linked thermosetting resins in weight percentages with AR grade epoxy resin. Then the reflection characteristics of these polymer composites, made as thin slabs was carried out by a transmission/ reflection method using a vector network analyzer R&S ZVA40, in the X and Ku-bands [8.0 to 18.0 GHz]. The microwave reflectivity properties of all these three blends were evaluated, and the epoxy modified styrene polymethyl methacrylate is found to be remarkably high upto - 50.2 dB at 14.1 GHz. The reflectivity of -10 dB or less could be obtained for a range of 7.4 GHz for the epoxy modified polydiphenylamine. The response slightly varies for all three samples. After due comparison of their response, epoxy modified polydiphenylamine and benzidine polyvinyl alcohol are deemed to be suitable as microwave absorber in the X and styrene polymethyl methacrylate is suitable in the Ku-band. The morphological features of the composites were examined using xray powder diffratogram and scanning electron microscopy.