Study On The Preparation And Properties Of Antibacterial Chitosan Derivatives/Lyocell Fibers

Chitosan, the most naturally occurring biopolymer, has good antibacterial activity with broad spectrum. Lyocell is a new process for cellulose fiber manufacturing cellulose fiber using its solution in NMMO/H₂O. Based on absolutely physical process, Lyocell is environment-friendly and replacing the traditional viscose process. Modifying cellulose fiber with chitosan and its antibacterial derivatives using this Lyocell process is an exciting approach to prepare naturally antibacterial fiber. Considering the bad solubility of chitosan and its derivatives in NMMO/H₂O, two dissolvable derivatives (ethylamine hydroxyethyl chitosan and sodium acetate chitosan) were prepared and their solubility and antibacterial activity were systemic studied. The co-solution of cellulose with ethylamine hydroxyethyl chitosan (EHCs) or sodium acetate chitosan (SACs) in NMMO/H₂O and their compound films were employed to research their phase behavior and rheology properties. Based on this, the fitting spinning dopes were used to prepare antibacterial fibers. The main work was summarized in the following statements: 1. The two derivatives were synthesized with better antibacterial activity and solubility, and the effect of reaction conditions on the degree of reaction and their properties was discussed. The best process for EHCs and SACs were at 80℃ with ratio of hydroxyethyl chitosan to Chloroethylamine 1:2 for 12 hours and 0℃ with mass ratio of chitosan to chloroactic acid 1.3:1respectively. Prolonging the reaction time was an effective factor for the reaction. EHCs, with abundant –OH and -NH₂ along its chain, behaves with stronger hydrogen bonding which lead to higher crystallity and thermal decomposition temperature than chitosan. For SACs, the reaction take place most at –OH. The chitosan with molecular weight between 5×10⁴ and 27×10⁴ was deemed to the appropriate one considering MW effect on the properties of the gained derivatives. 2. The results of rheology and spinnability indicate that the co-solutions are still Power-law fluid, but introduce of the derivatives including EHCs and SACs made the co-solution behavior more close to Newtonian fluid. The introduce of EHCs reduced ?η and Eη when its content below 5%, but the trend in the contrary way when EHCs increaseunceasingly. For SACs, the spinnability of the co-solution was improved. The results of Han-plots suggested that the co-solutions were both homogeneous in phase in which two polymers were taken as the same in behavior which led to a co-crystal in the cooling process between EHCs and cellulose. 3. The phase behavior of the compound film confirmed the existence of co-crystal which suggested the good compatibility in molecule level between EHCs and cellulose. For the other film, introduce of SACs took little influence on its properties of crystallity, dynamic mechanical and thermal stabilization. Both films got higher water-retention value than cellulose film which was beautiful for the goal fibers. 4. The tested antibacterial activity of both fibers were good when the content of antibacterial agent only 1% and still retained after washed several times. It is acceptant that introduce of chitosan derivatives deduce the stress intension slightly. At the same time, the value of elongation at break was enhanced. As a whole, the antibacterial fiber containing EHCs is superior to one containing SACs. The morphology and EHCs distributing in surface were investigate by SEM and XPS. The outcome suggested that EHCs was distributed well-proportioned and the phase was homogeneous.