Modified styrene-butadiene-styrene block copolymer as compatibiliser precursor in polyethylene/poly(ethylene terephthalate) blends

A styrene-butadiene-styrene block copolymer (SEBS) was functionalised with diethyl maleate (DEM) and added to very low density polyethylene (VLDPE)/poly(ethylene terephthalate) (PET) blends in the presence of Ti(OBu)4 as transesterification catalyst, to favour the formation of grafted copolymer during the reactive processing to improve the compatibility between the two immiscible polymers. SEBS was also functionalised with 2-hydroxyethyl methacrylate (HEMA) in order to obtain a more reactive compatibiliser precursor. The reactivity of the functionalised SEBS was compared by taking into account the functionalisation degree (FD) (determined by spectroscopic methods) and by performing selective extraction of the PET/modified SEBS 80/20 binary blends. Moreover the molecular weight determination of the polymer fractions by SEC chromatography and viscometric measurements allowed us to calculate the effective yield of PET grafting to SEBS chains.