Effect of Natural Phenolics on the Thermal and Processing Behaviour of Poly(3-Hydroxybutyrate)

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its relatively poor mechanical properties and narrow processing window. hi this paper, different natural phenol-based additives, including tannic acid (TA), grape bagasse extract (EP), and a lignocellulosic biomass (LC) were used as thermal and processing stabilizers for PHB. The thermal stability of both neat and doped PHB samples was studied by Theology and calorimetry. The experimental results showed that neat PHB massively degrades and that the addition of phenol additives enhances the thermal stability of PM, preserving the polymer molecular weight after processing. This finding was in agreement with the slower decay in viscosity observed through theological tests. Physical and chemical interactions between polymer and additive were considered as key factors to interpret the experimental data. LC affected the melt crystallization kinetics of PHB enhancing crystallization upon cooling. This finding suggests that LC was a heterogeneous nucleating agent, potentially able to control the physical aging of PHB. The described results are of interest for the development of sustainable alternatives to synthetic polymer additives, by increasing the applicability of bio-based materials.