Effect of plant tannin and glycerol on thermoplastic starch: Mechanical, structural, antimicrobial and biodegradable properties.

Thermoplastic starch is a good candidate for preparing biobased plastics. However, certain deficiencies in the ingredient, such as its poor mechanical strength and lack of antibacterial activity, need to be strengthened. In this work, a new method of producing TPS via extrusion and injection at a large scale was explored using tannin and glycerol simultaneously. The effect of the tannin content on the performance of TPS was investigated. The results showed that the synergistic effect of a small amount of tannin (2.5-7.5 wt%) and glycerol increased the tensile strength and maintained a stable elongation at break, and tannin aggregation occurred in TPS at higher tannin contents, which corresponded to increased tensile and flexural strengths. 15T-TPS has optimal mechanical performance with maximal relative crystallinity. The introduced tannin in TPS effectively enhanced the thermal stability but slightly reduced the biodegradability in soil and endowed TPS with antibacterial activity. Therefore, TPS containing tannins has the potential to be used in biomedical, food packaging and agricultural areas.