Improving the Process Ability of Poly (3-Hydroxybutyrate) by a Polyphenolic Natural Additive

The severe environmental issues generated by the non-biodegradability of most polymeric materials has fostered the search for more eco-friendly solutions. Polyhydroxybutyrate (PHB), produced by bacterial cells and easily hydrolyzed is one of appealing choice but its properties are still not competitive with those of standard polymers. Among others, one reason is related to the fact that the high processing temperature (due to the high crystallization point) is responsible for severe thermal degradation. In this paper, the effect of Tannic Acid (TA) as a thermal stabilizing processing agent for HPB is investigated by rheological as well as calorimetric techniques under conditions similar to those used in real processing applications. The results show that TA is effective in improving the thermal stability and processability of PHB, while keeping its biodegradable attitude. Compared to neat PHB, TA containing samples show a lower and delayed thermal degradation. FTIR measurements support the hypothesis that stabilization is determined by TA/PHB crosslinking.