Characterization of scrap poly(ethylene terephthalate)

The goals of the investigation were: to indicate the methods of characteriz ation of recycled polymers, to show general tendencies in properties deteri oration and characterize recyclates on Central Europe and European Communit y markets. The properties and composition of scrap poly(ethylene terephthal ate) from several sources were characterized by: TGA, DSC, FTIR, tensile pr operties, dynamic viscosity, intrinsic viscosity and thermooxidative stabil ity. We found that all PET regrinds contained admixture of other polymers ( 0.1-5 wt%). The presence of more than 50 ppm PVC makes PET worthless for ad vanced application as film forming, because it catalyzes the hydrolysis and reduces the strength of material. Although the individual flakes of recycl ed PET show almost unchanged molecular characteristics and properties, the processed regrinds always exhibit worse properties. Partial restoration of recycled PET properties can be achieved by careful working, removing the du st fraction and by proper drying. The difference between studied PET's resu lts from different applied recycling procedure. Admixtures of polymers with out compatibilizer always deteriorate tensile properties. Various levels of stability of polymer viscous flow during film and tape extrusion were obse rved, depending on composition of recycled PET from various sources. Microg els were observed in all samples during film extrusion. (C) 2000 Elsevier S cience Ltd. All rights reserved.