Twin-screw extruders (TSE) are widely used for compounding and polymer blending operations mainly because of their flexibility in providing varying levels of dispersive and distributive mixing independently. TSEs have also been used as continuous reactors for chemical reactions, such as polymerization and compatibilization. It is known that the reaction conversion can be improved using different process conditions, e.g., temperature, flow rate, screw speed and screw configuration, that can influence the reaction kinetics. However, not much is known about reactive extrusion when it comes to the evaluation of the reaction in-processing and along the extruder barrel, especially when the process condition is varied. In this work, the effect of screw rotation speed and feed rate on the compatibilization of the reaction of PA^ and PP-g-AA was evaluated by on-line ATR/MIR. The on-line ATR/MIR method, developed in house, was used to follow the reaction conversion along the extruder barrel in different location upstream the die, in real time. The area ratio of the peak of carbonyl stretching in amide present in PA6 at 1640 cm-1 standardized to the IR area of the peak at 1170 cm-1 relative to PP is applied to evaluate the evolution of the reaction of compatibilization between the amine end group in the chain of PA6 and acrylic acid grafted in the PP chain. Higher feed rates, which can be related with how full the extruder barrel is, and the screw speed influence the residence time distribution (RTD) along the extruder barrel, therefore, should have a significant impact in its kinetics. In order to study the extent of this influence, screw profiles were chosen to impose different types of flow in the melt, mild and aggressive extensional mixing elements recently developed by Maia and co-workers.