Bacterial cellulose (BC) gelatinous films prepared in stationary culture were dried by three different drying methods: hot air drying, vacuum drying and vacuum freezing drying. The structure of dried bacterial cellulose films was characterized using scanning electron microscopy (SEM), infrared spectroscopy (IR) and X-ray diffraction (XRD), and mechanical properties were tested. The results showed that the surface of films prepared by hot air drying were uniform and dense, cavities and cracks configurations existed in vacuum dried films, and layer and porous structures were observed in vacuum freezing dried films. FTIR spectra and X-ray pattern confirmed that vacuum freezing drying reduced the strength of hydrogen bonds between cellulose macromolecules and the degree of crystallinity of BC films but had little influence on the crystal structure. For those reasons, mechanical properties of BC films prepared by vacuum freezing drying were lower than that of those films by other methods.

The combustion properties, flame retardant property, thermal degradation and component of pyrolysis products of calcium alginate fibers were investigated in this paper. The limiting oxygen index value of calcium alginate fibers was 34.4 showing no combustion in the air. The fiber extinguishes instantly when it is moved away from the fire. During the combustion process, the heat release rates (HRR), effective heat combustion (EHC) and total heat release (THR) of calcium alginate fibers were lower than those of cotton fibers, but higher than those of sodium alginate. The carbon dioxide yield rate of calcium alginate fibers was higher than that of cotton fibers but lower than that of sodium alginate. Calcium carbonate and calcium hydroxide, which are beneficial to hamper fibers combustion and diffusion of heat and oxygen, were formed during thermal degradation of calcium alginate fibers. There were 15 kinds of pyrolysis products in gas phase of calcium alginate fibers at 350°C and 45 kinds at 700 °C, while there were 26 kinds of pyrolysis products of sodium alginate at 350°C and 26 kinds at 700°C. Based on a series of study, the flame retardant mechanism of calcium alginate fibers was analyzed.

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Cotton fabric with excellent antibacterial properties was obtained by treated with polyamide-amine (PAMAM) dendrimers as a carrier and silver nitrate as an antibacterial agent. The antibacterial cotton fabrics were prepared by the methods of one-bath process and two-bath process. Antibacterial activity of cotton fabrics treated by two different methods was good, but the antibacterial durability of cotton fabric treated with two-bath process was better than that treated with one-bath process. After 50 washing cycles, cotton fabric treated with two-bath process still had good antibacterial property and its inhibitory rate to Gram-positive S. aureus and Gram-negative E. coli was over 99 %. It was found that the breaking strength retention of finished cotton fabrics was 85.83 % and the decrease of cotton fabrics’ whiteness index was about 15 %.