Blends of ethylene-co-vinyl acetate and poly(3-hydroxybutyrate) with adhesion property

The structure and properties of ethylene-co-vinyl acetate (EVA) and poly(3-hydroxybutyrate) (PHB) blends depended on their PHB content, i.e. PHB phase dominated the structure for amounts of PHB higher than 50 wt%, whereas EVA phase is dominant for PHB content lower than 50 wt%. EVA/PHB (70:30) blend showed unexpected different structure because of higher miscibility and the creation of new interfacial interactions between C=O and CH3 groups of PHB and CH3 and C=O groups of EVA, these interactions led changing of the phase structure of ethylene and vinyl acetate domains in EVA. As a consequence, improved thermal, viscoelastic and morphological properties were obtained. EVA+PHB blends containing 60 wt% or more PHB did not show tack and, interestingly, the addition of 20–30 wt% PHB enhanced the tack and displaced the maximum tack of pure EVA to lower temperature. The tack of EVA/PHB (70:30) blend was the highest among all blends because of its particular structure, fibrillation was also shown. Finally, the adhesion of EVA+PHB blends containing 20–30 wt% PHB to polypropylene (PP) substrate was higher than the one of pure EVA because of the interactions between the ethylene domains in EVA phase of the blend and PP substrate surface