In rigid poly(vinyl chloride) (PVC)-lignin (L) blends the possibility of forming intermolecular interactions between the PVC and L can take place only at low L loading (up to 10 parts). At high L loading there is an imbalance between the tendency of L molecular components to associate by H-secondary bonds, and the potential for forming intermolecular bonds with PVC. Our studies have shown that specific plasticizers could break parts of the H-secondary bonds present in L, thus creating possibilities of interactions at a molecular scale with other polar polymers by forming intermolecular bonds. The presence of specific plasticizers strongly influences the properties and the morphology of the blends, and permits higher L loading. The data regarding the properties of plasticized copolymer (vinyl chloride-vinyl acetate) (VC-VAc)-L blends show the important role of these specific plasticizers. Some results show also the possibility of L-filler interaction. The blends were studied with regard to their morphology by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM) and with regard to their mechanical properties by tensile testing.