Specific mechanical energy (SME) is a measurement commonly used in industry for the characterization of extrusion runs and degree of dispersion in composites, however, it has never been used to evaluate the reaction efficiency during the reactive extrusion of polymer blends. This work studies for the first time, the influence of the SME on the reaction efficiency and stability of the material during the reactive extrusion of Polypropylene carbonate (PPC) and Polybutylene succinate (PBS) and the likelihood of optimizing the process in question. Compounding runs at different screw speeds (reaching speeds of 1000rpm) and flow rates were conducted while maintaining the same amount of SME. A premade compatibilizer based of MAH and PPC was added to the blends at different amounts (5 to 25 wt%) while keeping the blend ratio the same for all the runs. Different characterization techniques were carried out to study the reaction efficiency and stability of the products. The grafting efficiency increased with the addition of compatibilizer and happened to have the same value for samples compounded at different processing conditions. The proton NMR spectra of all the samples with compatibilizer showed evidence of the formation of copolymer in the system. A more significant decay in viscosity was found for blends compounded at lower flow rates than then ones made at higher screw speeds. Also, more evidence of graft reactions was seen due to a change in the shear thinning behavior in blends extruded at longer times than the ones made at higher shear. Finally, scanning electron microscopy images showed that the compatibilizer successfully suppressed the coalescence of the PPC droplets and improved the interface between the phases. It was concluded that is it possible to carry out the functionalization of PPC and PBS and obtain blends that are stable at much shorter residence time if enough shear is imparted in the system (carry out reactive extrusion at high speeds).