This paper presents a study of radar absorbing materials (RAM), based on conducting polymer polypyrrole (PPy) and organic-inorganic nanocomposite of PPy filled with lamellar structure kaolinite clay (PPy/Kao) for X-band frequency range application. PPy was obtained via a chemical synthesis using doping agent chloride acid, lauric acid, and sodium dodecyl sulfate. The nanocomposites were produced via in situ polymerization, where the same experimental conditions were applied for PPy synthesis. The radar absorbing composite was obtained by mechanically mixing an epoxy resin matrix with the synthesized materials. The characterization was done using infrared spectroscopy, scanning electron microscopy (SEM), thermogravimetric analyses, and differential scanning calorimetry thermal analysis, and electromagnetic measurements. Kao in the nanocomposite was used to promote polymer
All over the world standards for Gel Permeation Chromatography (GPC) are produced using ionic polymerization. Standards are commercialized in a broad range of molecular weight and their dispersity (Ð) must be lower than 1.1. This work proposes the synthesis of polystyrene standards using Nitroxide Mediated Polymerization (NMP), an alternative technique to produce controlled polymers that is much more robust when compared to ionic polymerization. Standards with different ranges of molecular weights were obtained, all of them with very narrow molecular weight distribution (MWD) and dispersity (Ð) lower than 1.10. In order to do that, several combinations of different initiators were tested. Advanced GPC Triple Detector was used to obtain important properties, such as absolute number and weight average molecular weights, dispersity and intrinsic viscosity. The analytical method used in the characterization of the samples was inhouse validated in terms of linearity, accuracy, precision, repeatability and robustness. The validation study demonstrated the quality of the measurements and ensured that the information obtained for a given analyte by the GPC technique is reliable.
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