A preliminary investigation on the use of poly(ethyleneterephthalate-co-?-caprolactone) copolymer as compatibiliser of HDPE/PET blends

A preliminary study on the possibility to use the copolymer poly[(ethylene terephthalate)-co(epsilon -caprolactone)] as a compatibilising agent in blends of high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) is reported. The copolymer was synthesised by polycondensation of low-molecular PCL precursors, previously end-capped with reactive isocyanate groups, and oligomers of PET obtained from PET waste through a controlled depolymerisation procedure. HDPE/PET blends at a composition of 70/30 w/w with and without the addition of 10 wt.-% of compatibiliser were prepared in a single-screw mixer extruder. The effect of compatibiliser was evaluated by studying the thermal, dynamic-mechanical and mechanical properties and the morphology of the blends. The compatibiliser was found to be a good emulsifying agent from a morphological point of view. Nevertheless, the mechanical properties of the blend were not improved by the addition of the compatibiliser.