Miscibility and carbon dioxide transport properties of blends of bacterial poly(3-hydroxybutyrate) and a poly(vinylidene chloride-co-acrylonitrile) copolymer

The purpose of this work is to study the CO2 transport properties of isotactic poly(3-hydroxybutyrate) (iPHB) blended with a miscible second component, a copolymer of vinylidene chloride (VDC) and acrylonitrile (AN) units. All the investigated blends are rubbery, allowing a reasonable strategy to tough PHB without impairing its original biodegradability. The miscibility required for this purpose was confirmed by differential scanning calorimetry, measuring both the glass transition and melting temperatures of the blends. The melting point depression induced by the copolymer was used to quantify the interactions between the components of the blend. Carbon dioxide transport properties of blends having less than 50% by weight of the copolymer were measured by gravimetric sorption experiments in a Cahn electro balance. The effect of the VDC-co-AN copolymer was to decrease the diffusivity and permeability of the pure iPHB due to its well-known high barrier character.