The discussion covers physical recycling of thermosetting polyurethanes(PU) in a closed loop recycling system. The recovery of PUs are followed by grinding with the conversion into secondary granules. These granules are introduced as a filler into cross-linked PU as well as linear PU matrices. The compatibility between filler and matrices and resulting properties are investigated with the variables of filler content, swelling time, and surface characteristics of fillers. While the increase of the filler content up to 10 wt% improved the mechanical properties of the composites, further increase of the filler content began to deteriorate those properties. A adhesion between filler and matrix was improved as the swelling time increased, possibly due to the interpenetration of poly(propylene glycol)oxide into the filler granules. In addition, reactive fillers resulted in significant improvements of the mechanical properties, especially with excess OH groups.