Miscibility behaviour of amorphous poly(3-hydroxybutyrate) (a-PHB)/styrene–vinyl phenol copolymer (STY-co-VPH) blends applying an association model

In this work a Fourier transform infrared (FTIR) study of blends of styrene–vinyl phenol copolymers (containing different proportions of styrene) with atactic PHB is presented. The equilibrium constant describing phenolic OH/ester carbonyl hydrogen bonds (KA) has been experimentally determined from the quantification of the hydrogen-bonded carbonyl group fraction as a function of temperature, and the effect of functional group accessibility on KA values has been discussed. An average value of KA=41 has been employed to perform a prediction of miscibility maps employing the association model of Painter and Coleman. A fairly good agreement between theoretical predictions and experimental results has been obtained.