Reprocessing of polyethyleneterephthalate and characterisation of monopolymer blends of virgin and recycled polymers

Recycling of polyethyleneterephthalate (PET from bottles is considered by changing both reprocessing machines and the effect of humidity. The rheological and mechanical properties of this recycled material remain very close to that of the virgin material provided that a careful drying is carried out before any melt operation. The reprocessing has been carried out mainly in view of the use of this secondary material in blends with virgin PET-monopolymer or homopolymer blends. Indeed, this use is a common industrial practice to reuse plastic scraps. Most monopolymer blends show properties between those of the two components but in some cases lower than those expected on the basis of an additive rule. In some cases minima in the properties-composition curves are observed. This occurs mainly when the properties of the two components are very similar. Blends with similar amounts of the two components should be then avoided. On the contrary, when the characteristics of the virgin and of the recycled component are very different, the properties of the blends are determined by those of the matrix.