PREPARATION AND ANTIMICROBIAL PROPERTIES OF PVA/TANNIN BLEND FILMS

Wattle tannin(TN),a kind of polyphenols compound originated from black wattle,was introduced into poly(vinyl alcohol)(PVA) to prepare PVA/TN blend films by solution blending method.Glutaraldehyde was used to slightly crosslink PVA/TN blend films.The PVA/TN blend films were characterized by scanning electron microscopy(SEM),wide-angle X-ray diffraction(WAXD) and differential scanning calorimetry(DSC).The SEM observations revealed that PVA and TN was miscible in the blend films,which may due to the strong intermolecular hydrogen bonding between the hydroxyl groups from PVA and TN.The melting temperature of the blend film decreased from 231.7℃ to 221.3℃ when the TN content in the blend film increased from 0 to 20%,but the crystallinity of PVA was slightly decreased.It was found that less than 1.8% of the total amount of TN in blend films could be leached out when the blend films were soaked in water even for 24 h.This implies the good stability of PVA/TN blend films in water,which is beneficial to the long duration of antibacterial activity.The antibacterial activities of PVA/TN blend films were challenged by Escherichia coli(CMCC 44103),Staphylococcus epidermidis(ATCC 12228) and Staphylococcus aureus(ATCC 6538) with contact mode.The results showed that with the addition of TN,these PVA-based polymer films exhibited strong antibacterial activities against both gram-negative and gram-positive bacteria.For instance,only 0.5% of E.coli was survived on the blend film with 20% TN after 1 h contacting.Therefore,the PVA/TN blended films may have great potential in packaging material and coating fields.