PVA对生物合成细菌纤维素膜拉伸性能的影响

The Effect of Polyvinyl Alcohol on Tensile Property of Biosynthesized Bacterial Cellulose Membrane

BC膜生物合成的过程受培养基中加入不同浓度PVA的影响,会产生拉伸性能各异的BC膜。培养基中添加低浓度(20和40 g·L·1)聚乙烯醇(PVA)后BC膜产量和拉伸强度等指标均有提高,培养至96 h时20和40 g·L·1 PVA浓度的培养基中BC产量分别比对照组高出40.48%和16.9%,此时40 g·L·1 PVA培养基中BC膜的弹性模量和拉伸强度最大,分别为4.56 GPa和66.8 MPa;而添加高浓度(60和80 g·L·1)PVA后BC膜产量和拉伸强度均降低。X-射线衍射结果显示培养基中低浓度的PVA可以提高膜的结晶度,而高浓度的PVA降低BC膜的结晶度;扫描电镜照片显示培养基中添加低浓度PVA后形成的BC膜结构更为致密均匀。

The synthesis process of BC （bacterial cellulose） is influenced by different concentrations of added PVA, and the BC membranes with different tensile properties can be then produced. The yield and the tensile strength of the prepared BC membranes can be improved when the concentration of PVA in the medium is low （20 and 40g·L-1）. After 96 h fermentation, the yield of BC membrane cultured in medium with addition of 20 and 40 g·L-1PVA are 40.48% and 16.9% higher than that of the control group （cultured in the medium without adding PVA）, respectively; while with the addition of 40g·L-1 PVA in the medium, the elastic modulus and tensile strength of the synthesized BC membranes reach their highest levels which are 4.56 GPa and 66.8 MPa, respectively. By contrast, both the yield and the tensile strength of the BC membranes produced in the medium supplemented with higher concentration of PVA （60 and 80 g·L-1） will be decreased. According to the XRD spectra, the influence of different concentrations of added PVA in the medium shows opposite trends; that is, low concentration of PVA added leads to higher crystallinity while high PVA concentration leads to lower crystallinity. According to their SEM photographs, the texture structures of BC membranes prepared in mediums with different concentrations of PVA were compared. It was found that the membranes cultured from low-concentration-PVA loaded medium show much denser and more even.