As concluded by SYSTEMIQ, mechanical recycling approach for plastics will dominate for decades. To elucidate the origin of the thermomechanical performance deficiencies of polymer blends, a computational-experimental multiscale approach digging into the blend microstructure is required. This approach can efficiently guide the eco-oriented design of polymer blend and their usability. This project will build upon a recent proposed model to describe with unprecedented accuracy the thermomechanical behavior of both amorphous and semi-crystalline polymers. This development, that enables temperature-, pressure- and rate-dependency in pure polymers, will be extended for polymer blends by incorporating the microstructural details in connection to its mechanical recycling history. To integrate the microstructure revealing the structure-property relationships in polymer blends, a multiscale framework relying on a bottom-up approach is proposed. 3D microstructure reconstruction of polymer blends will be obtained from advanced image analysis methods, transferring to high-fidelity Finite Element simulations. Homogenization techniques will be conducted to disclose the effect of the microscopic details in the observable macroscopic response. The aim is to deliver a scientifically robust model for a wide variety of mechanically recycled polymer blends allowing (i) to increase the after-use pathway and (ii) to increase their usability in mechanically-based applications.