Assisted compatibility, and balanced regulation of the mechanical, thermal, and antioxidant activity of polyvinyl alcohol-chinese bayberry tannin extract films using different di-aldehydes as cross-linkers

Abstract

Polyvinyl alcohol (PVA)-based films containing Chinese bayberry tannin (BT) were prepared by cross-linking using glyoxal, glutaraldehyde and dialdehyde starch, individually. The presence of cross-linkers was evident to promote the transparency and decrease the moisture content of PVA/BT films, while the water solubility stayed almost unchanged in the cross-linked PVA/BT films. All cross-linkers provided promotion of the water vapor permeability, mechanical property and thermal stability of PVA/BT films. The best water vapor barrier capacity was found in case of glutaraldehyde cross-linked PVA/BT film, while the highest tensile strength was encountered in case of glyoxal cross-linked PVA/BT films, compared with the uncross-linked films. The scavenging action of the films towards DPPH radical activity was influenced by the nature of each cross-linker. Namely, the PVA/AT film cross-linked by glutaraldehyde acquired the lowest radical scavenging activity in a certain time, suggesting that glutaraldehyde decreased the release rate of BT from PVA. Based on the experimental data, glutaraldehyde and dialdehyde starch could be more suitable for PVA/BT film preparation since they can promote the intermolecular interaction of PVA and BT to a reasonable extent.