Improvement of the compatibility between poly(3-hydroxybutyrate) and poly(8-caprolactone) by reactive extrusion with dicumyl peroxide

Poly(3-hydroxybutyrate) is a biodegradable aliphatic polyester obtained through bacterial fermentation that has gained attention in the last few years; nevertheless, its industrial applications are restricted because of some drawbacks related to its high stiffness and fragility which is associated to its high crystallinity. In this work, poly(3-hydroxybutyrate) (P3HB) was melt blended with poly(epsilon-caprolactone) (PCL) at a constant weight ratio of 75125 (P3HB/PCL) by reactive extrusion with different contents of dicumyl peroxide (DCP) in the 0-1 wt% range. The effects of the DCP load on mechanical, thermal and morphology of the P3HB/PCL blend were studied. Results showed a positive increase in the elongation at break and the impact-absorbed energy of 91% and 231% respectively with regard the uncompatibilized P3HB/PCL blend by the addition of 1 wt% DCP, being this a clear evidenced of the improved compatibility between these polymers. Moreover, morphology of DCP-compatibilized P3HB/PCL blend obtained by field emission electron microscopy (FESEM) and atomic force microscopy (AFM) showed a remarkable decrease in the particle size, of poly(epsilon-caprolactone)-rich domains randomly dispersed in the poly(3-hydroxybutyrate). In addition, both FESEM and AFM also revealed improved interfacial adhesion between P3HB- and PCL-rich phases with a noticeable decrease in the gap between them. Addition of 1 wt% DCP also contributes to lowering the degree of crystallinity of PHB by 14% in the blend and other thermal properties are not highly affected by the reactive extrusion with DCP. (C) 2016 Elsevier Ltd. All rights reserved.