Effect of drying method on properties and structure of bacterial cellulose film

Effects of drying methods( direct drying,freeze drying,and homogenization drying) on the properties( thickness,water absorption water vapor permeability,light transmittance,mechanical properties,and so on) of bacterial cellulose film prepared by Acetobacter xylinus were investigated by measuring the thickness,water absorption,water vapor permeability,light transmittance and mechanical properties of filmsstudied.The film was prepared by Acetobacter xylinus. Meanwhile,the structure of bacterial cellulose film was analyzed utilizing by infrared spectroscopy and scanning electron microscopy( SEM) in order to reveal the mechanism of drying method to the film properties.There was a significant effect of drying method on the properties of bacterial cellulose films. The thickness,water absorption and water vapor permeability of freeze drying film were 0.47 mm,88.14% and 53.28 g / m2,respectively,which were apparently higher than that of the other films( p <0.05). The tensile strength of the direct drying film was 46.7 MPa,and the break elongation of the freeze drying film was 4.48%,which were apparently higher than that of the other films( p < 0.05).The light transmittance of direct drying film was best,and there was a positive correlation between the light transmittance and wavelength in the direct drying and homogenization drying films. The light transmittance of three kinds of films( prepared by direct drying,freeze drying,and homogenization drying) were 35.21%,69.27%,and 8.91%,respectively( p < 0.05).The structural structure of freeze drying sample was loose and pertusate by according to the SEM scanning electron microscopy analysis. The structural structure of direct drying and homogenized drying sample films was compact.The SEM results were highly consistent with the porosity of films.According to the infrared spectroscopy analysis,there was characteristic absorption peak of cellulose among the three kinds of films samples and the characteristics of the peak were affected by the drying methods.Thus,the impact of the drying methods had a significant effect on the bacterial cellulose film structure,and the properties of bacterial cellulose films were also affected by the drying methods.