This article reports on the interfacial modifications induced by different amounts of a succinyl-fluorescein grafted atactic polypropylene (a-PP-SF) as a truly interfacial agent. in polypropylene/talc composite materials. The a-PP-SF used, which contains 4% grafts, was previously obtained in our laboratory by chemical modification of a byproduct from industrial polymerization reactors. Thermal and mechanical analyses of composites, performed under dynamic conditions, led to the correlation of parameters at the microscopic scale with others at the macroscopic scale. Thus, the interfacial effect caused by different amounts of a-PP-SF in the composite can be concluded by observations made at either scale.