Development of Antioxidant Packaging Film Based on Chinese Bayberry Tannin Extract and Polyvinyl Alcohol

The current work explores the potential use of commercial Chinese bayberry tannin(BT)to develop antioxidant PVA-based films using solvent casting process for packaging applications.The effect of BT concentration on opa-city,water resistance and antioxidant capacity of resulting films was investigated.Properties like tensile strength,thermal behavior,and morphological aspects were also characterized.The experimental results showed that PVA/BT films formed with uniformly brown color and generally good transparency,offering good antioxidant ability.The PVA film containing BT presented slightly higher water resistance according to the results of moisture content and water vapor permeability,especially at low BT content(<10 wt%).The PVA can be compounded with up to 10 wt%BT without any obvious deterioration in the tensile strength.The PVA/BT films exhibited better thermal degradation behavior compared with PVA alone because of the chemical bonds of PVA-BT and the for-mation of char at high temperature.Based on the results,PVA incorporated with Chinese bayberry tannin may provide broader formulation options for packaging materials with antioxidant action.

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

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/BTfilms.All cross-linkers provided promotion of the water vapor per-meability,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 intermo-lecular interaction of PVA and BT to a reasonable extent.

Highly active Pd-Fe/α-Al_(2)O_(3) catalyst with the bayberry tannin as chelating promoter for CO oxidative coupling to diethyl oxalate

A novel Pd-Fe/α-Al_(2)O_(3) catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring a-Al_(2)O_(3) as support for the synthesis of diethyl oxalate from CO and ethyl nitrite.A variety of characterization techniques including N2 physical adsorption,optical microscopy,scanning electron microscopy and energy dispersive system(SEM-EDS),inductively coupled plasma optical emission spectroscopy(ICP-OES),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),were employed to explore the relationship between the physicochemical properties and activity of catalysts.It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd,reduce the particle size and make the active Pd as a multi-ring distribution on the commercial a-Al2O3 suppo rt,which we re beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite.0.3 wts Pd-Fe/α-Al_(2)O_(3) showed excelle nt catalytic activity and selectivity in a continuous flow,fixed-bed reactor with the loading amount of 10 mL catalysts,Under the mild reaction conditions,the space-time yield of diethyl oxalate was 978 g L^(-1) h^(-1) and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.