In this study thermal and mechanical properties and chemical structure of four different polymers (PE, PP, polyASA and PVC) were investigated to find out if the recycled polymers had the same properties and can be used in the same applications as the virgins or not. FT-IR was used for investigation of chemical structure. TGA, DSC and thermal stability were used to compare the thermal properties. Tensile test also used to examine the mechanical properties. All the tests showed the recycling process is not done completely well. The differences in results for virgins and recycled samples are the reasons which verified this claim. The results obtained from this study clarifying that the amount of stabilizer in the recycled polymers were considerably less than the amount in virgins, means that the company had not added enough stabilizer during the recycling process.