Effect of Lignosulfonate on the Thermal and Morphological Behavior of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The effect of lignosulfonate on poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, was studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PHBV/lignosulfonate samples were prepared by melt mixing in an internal mixer. SEM showed that PHBV/lignosulfonate samples present a cracked surface that is more intense in mixtures with high lignosulfonate proportions. According to DSC, melting and glass transition temperatures of the PHBV matrix decrease with lignosulfonate addition. The same effect was observed for melting enthalpies (ΔHm), which indicates a decrease of crystallinity. TGA showed that thermal stability of PHBV/lignosulfonate samples was shifted to lower temperatures, which indicates the existence of an interaction between the thermal decomposition processes of PHBV and lignosulfonate.