Thermo-mechanical method can be used in PET fiber wastes, polypropylene wastes, polyamide wastes, etc. Thermo-mechanical method is based on re-melt- ing of thermoplastic wastes to obtain re-granules. Re-granules can be used in staple fiber production or in plastic industry. Due to the degradations and viscosity drops, re-granules are used in staple fiber production. Solid state post-condensation can be used to increase viscosity, however the process requires very high energy.