Blending poly(3-hydroxybutyrate) with tannic acid: Influence of a polyphenolic natural additive on the rheological and thermal behavior

• Poly(3-hydroxybutyrate) (PHB) has been blended to tannic acid (TA).
• TA addition improves the thermal properties of the neat PHB.
• TA addition widens the processability temperature window.
• A crosslinking mechanism between PHB and TA could justify the experimental data.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its relatively poor mechanical properties and narrow processing window. In this paper, a natural polyphenolic additive, tannic acid (TA) was used as thermal and processing stabilizer for PHB. The thermal stability of both neat and TA-doped PHB samples was studied by rheology and calorimetry. The experimental results show that the neat PHB massively degrades and that the addition of tannic acid enhances the thermal stability of PHB, thus widening the processing window of the polymer. Physical and chemical interactions between the polymer and the additive were considered as key factors to interpret the experimental data. The described results are of interest for the development of sustainable alternatives to synthetic polymer additives, by increasing the applicability of bio-based materials.

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