Study On Modified Chitosan Fiber

In recent years, much attention has been focused on the modification of natural polymers toproduce high polymer material, lower price, nontoxic and biodegradable. Graftcopolymerization is one of the most attractive methods to modify natural polymers.The chitosan fiber is widely used in the fields of textile, medical treatment, environmentprotection and so on, because it has excellent biocompatibility and is readily biodegradable.The reason of the greater solubility is there are many free amine groups and hydroxyl groupson the chitosan backbone, and which is much easier and more conveniently for the processingor treatment of chitosan. Alkylation, acylation, grafting, crosslinking could be happened withthe amine groups and hydroxyl groups. The modified chitosan can be prepared to extend itsapplications.In this study, graft copolymerization of acrylic acid onto chitosan in by ammoniumpersulfate was investigated. This way was simple, which not only supply a new key but alsobreadth the design thinking method of changing the chitosan’s character. Generally, chitin isproducts extracted from shrimps and then deacetylated to obtain chitosan. The degree ofdeacetylation of chitosan is about74.2%.The graft maintained at copolymerization reaction was carried out in a three necked flask75℃under nitrogen atmosphere in a homogeneous phase (containing a smallpotion of aceticacid) by using ammonium persulfate as an initiator. Evidence of grafting was obtained bycomparing FTIR spectra of chitosan and the graft copolymer as well as SEM of the products.The synthetic conditions were systematically optimized through studying the influentialfactors, including temperature, concentrations of initiator, concentration of acrylic acidmonomer (AA), effect of reaction time on grafting. In order to gain the best mechanicalproperties, it was found that the optimum synthesis conditions are as follows: the mass ofchitosan is0.6g, the mol ratio of the ammonium persulfate and acrylic acid is0.01,and thevolume ratio of absolute alcohol and10%sodium hydroxide is50:50.The breaking strength offiber is0.55CN/dtex，and the elongation is367%. In order to gain the best swelling properties, it was found that the optimum synthesis conditions are as follows: the mass of chitosan is0.5g,the mol ratio of the ammonium persulfate and acrylic acid is1.5%, the reaction time is3h,and the volume ratio of absolute alcohol and10%sodium hydroxide is30:70. The bestswelling ratio of the fiber is275.67g/g.The chitosan fibres being used now are usually made by means of wet spinning. But thestrength is much lower. In this study, using glutaric dialdehyde as cross linker, at certainconditions, Preparation of chitosan fibers with high strength. Chitosan fibers can reach thehighest rupture strength2.03CN/dtex.