Study On The Preparation, Structure And Properties Of Alginate Fiber

Alginate sodium has attracted great attention in the area of biologicalmedical materials due to its unique biological properties. Alginate fiber canbe used to prepare medical dressing because of its good hygroscopic property,but its low tenacity greatly hinders its application area. Therefore, thepreparation technology of alginate fiber with good mechanical properties hasbeen as an important research direction in this area in recent years. Thepurpose in this dissertation is to prepare the alginate fiber by using wetspinning and make the fiber has anti-bacterial property through cross-linkingreaction with Chitosan.The rheological behavior of alginate dope was studied and the spinningtechnology on the fiber tenacity was discussed. The hygroscopic property,absorptive property to metallic ion and flame retardant property of thealginate fiber were tested. Chitosan was used to graft with alginate fiber andthe crossing-linking mechanism was approached. The effect of the graftingreaction on the fiber tenacity was systematically studied and the antibacterialcapability of the fiber was tested. Based on above research works, the mainresults obtained are as follows:1. The viscosity of the solution alginate sodium increases whit the increase ofthe concentration of the solution. The saturated concentration of the spinningalginate sodium is 6% and which was obtained by dissolving the alginatesodium powder for 3h and deaerating under vacuum for 18h.2. The dope exhibits Newdonian fluid behavior with n about 1at lowerγregion. With theγincreasing, the dope exhibits a behavior of pseudoplastic fluid with shear thinning character (n＜1) and theηa of the doe decrease. In awide range of shear rates, theηa is dependent on the temperature. Theactivation energy for the viscous flow of the dope is decreased with theincreasing of concentration andγ. The extent of the structured dope isdecreased with elevating the temperature and reducing the concentration.Therefor, to suitabty elevate the temperature of dope is profitable for the wetspinning.3. The alginate fiber with good break-down strength can be prepared by wetspinning and the solution is distilled water.4. Analysed by FT-IR, the ionic interchange is happened between Na⁺ andCa²⁺ during the spinning process and the "Egg-box" structure is formed. TheDSC curve proves that the thermal breakdown of the alginate fiber can befulfilled by two steps. The first step is happened when the temperature isincreased to 5O～150℃, the inner water of the fiber is lost. When thetemperature is increased to 220～280℃,the second step is happened and thefiber is cracked completely.5. M/G values are increased under the same spinning process, the degree ofswelling of the alginate fiber increases, however, the break-down strength ofit decreases. Gradually increasing the concentration of alginate sodium, thebreak-down strength of the fiber increases until the concentration is up to 5%.The break-down strength of the fiber increases with the increase of theconcentration of coagulation bath.6. The absorptive ability to different substances varies in such order.physiological saline＞blood＞tap water＞distilled water. The absorptiveability of the alginate fiber increases with the increase of M/G value and theconcentration of sodium-alginate. Gradually increasing the concentration of coagulation bath, it increases until the concentration is up to 5%. However, itreduces with lasting coagulating time.7. The THR of the alginate fiber is much higer than that of cotton fiber, andthe HRR of the alginate fiber is lower than that of cotton fiber. Thecombustion process of the alginate fiber is very low and the TTI of alginatefiber is 18s while the TTI of cotton fiber is 2s, so the fire retardant proprietyof the alginate is better than cotton fiber.8. Alginate fibers can absorb some metallic ions and the absorptive ability ofthe alginate fiber increases with the decrease of M/G value.9. The ionic attraction is happened between chitosan molecules and sodiumalginate molecules and the break strength of the chitosan/alginate fiber ishigher than that of pure alginate fiber. When the content of the chitosan in thecoagulation is low, there is little chitosan in the surface of the fiber, so theantibacterial properties of the fiber is poor. Increasing the content of thechitosan in the coagulation bath, more and more chitosan react with sodiumalginate, so the antibacterial property of the fiber is increased.