Unsaturated polyester resin (UPRc) was synthesized from maleic anhydride (MA) and products of glycolysis. Oligo-polyethylene terephthalate (OPET) and oligo-cellulose (OC) were obtained by depolymerization of polyethylene terephthalate (PET) waste and paper waste, respectively, both with triethylene glycol in the presence of a catalyst. OC and OPET glycolyzed product and UPRc were characterized by gel permeation chromatography, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and nuclear magnetic resonance (H-1-RMN, C-13-RMN, HSQC). Measurements showed that the initial morphological integrity of OC changed due to incorporation of semicrystalline OPET in ploycondensation with MA. Results reflect the enhanced hydrophobicity and thermal stability of the cellulose as a consequence of esterification.