Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

<strong>Abstract</strong><span>The aim of this study was to identify and compare the effect of ultrasound (US) and microwave (MW) irradiation on the assisted synthesis reaction to obtain cationic corn and potato starch derivatives, with cationizing agent (3-chloro-2-hydroxypropyl)-trimethylammonium chloride in solutionand in limited solvent conditions, known as a paste process. The starch derivatives were characterized by techniques, such as Fourier Transformed Infrared Spectroscopy, Thermo Gravimetric Analysis, Differential Scanning Calorimetry, Scanning Electron Microscopy and Atomic Force Microscopy.The application of both (MW) and (US) irradiation as energy sources permitted the shortening of the etherification time to minutes from the previously reported 18 hours of traditional heating. The results show the high potential of alternative energy sources to innovate and increase the efficiency of a technological starch derivatization process.</span><br /><strong>Keywords:</strong><span> Cationic starch, characterization, microwave, synthesis, ultrasound.</span>