Photothermal methods and atomic force microscopy images applied to the study of poly(3-hydroxybutyrate) and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) dense membranes

Thermal and transport properties of some polyhydroxyalkanoates (PHAs), poly-3-hydroxybutyrate and poly-3hydroxybutyrate-co-3-hydroxyvalerate copolymers at different concentrations (8, 14, and 22%), were studied by using photoacoustic and photothermal techniques. Mass diffusion coefficients were obtained for carbon dioxide and oxygen by using a gas analyzer. Specific heat capacity measurements were performed by monitoring temperature of the samples under white light illumination against time. Thermal diffusivities were determined by using the open photoacoustic cell configuration. The results were discussed considering the incorporation of hydroxyvalerate units in the poly(3-hydroxybutyrate) unit cell and were correlated with atomic force microscopy images of the upper surface of membranes. New information on transport properties of PHAs is provided.