Carrageenan Fiber Formation Process And Flame Retardant Mechanism Research

Carrageenan is a natural sulfur-containing polysaccharide extracted from red algae.It is widely used in food,medicine and daily chemical industry because of its good gel properties.In this thesis,K-Ca type ?-carrageenan fiber(?-CAF-K,Ca)and Ba-Ba type ?-carrageenan fiber(?-CAF-Ba,Ba)were prepared by wet spinning technique and ?-CAF-Ba,Ba was obtained with barium chloride in coagulation bath and stretch bath while the ?-CAF-K,Ca was obtained with potassium chloride solution as a coagulating bath and calcium chloride solution as a stretch bath.The fiber formation process and flame retardant mechanism of these two fibers were investigated by SEM,EDS,intensity determination,LOI,TG,MCC and Py-GC-MS analysis.SEM showed that the ?-CAF-K,Ca had a rugged cross section and many surface gullies,while ?-CAF-Ba,Ba had a smooth cross section and few surface gullies.The mechanical properties test showed that the breaking strength and breaking elongation of ?-CAF-K,Ca were 0.57 cN/dtex and 10.23%,respectively,while those for ?-CAF-Ba,Ba were 0.78 cN/dtex and 9.34%.Combined with EDS analysis,it is found that during the formation of ?-CAF-K,Ca the potassium ions were combined with the sulfate group in the carrageenan by ion bonding that made the potassium-calcium carrageenanfibers form a gel structure,which was a relative loose spatial network,while during the formation of ?-CAF-Ba,Ba barium ions reacted with the sulfate groups of carrageenan to induce barium carrageenan fibers form a precipitated structure,which was a relative close spatial network.SEM,LOI,MCC and TG showed that ?-CAF-K,Ca and ?-CAF-Ba,Ba could maintain fiber morphology at 700 °C,and the LOI value were both exceeded 27,which indicates that both ?-CAF-K,Ca and ?-CAF-Ba,Ba have good flame retardant properties.However,the residual carbon content of the ?-CAF-Ba,Ba was about 33.2%;while the residual carbon content of the ?-CAF-K,Ca was about 23.9%.Combined with pyrolysis products analysis,the flame retardant mechanism of the two fibers can be preliminarily obtained.At the same time,two possible pyrolysis pathways of ?-CAF-K,Ca are inferred.In order to improve the strength and flame resistance performance another kind of carrageenan fiber(?-CAF-K,K,?-CAF-K,Ca and ?-CAF-K,Al)was prepared by using ?-carrageenan solution as the spinning dope and potassium chloride solution as a coagulating bath and a series of ions chloride solution as stretch bath,and their mechanical properties and flame retardant properties were preliminarily studied.Through the analysis of the morphology,mechanical properties and flame retardant properties to the three fibers,it can be seen that ?-CAF-K,Al had good morphology and excellent mechanical properties and its breaking strength reached 1.25 cN/dtex.Its LOI value was up to 39,and it still maintained good fiber morphology after burning at 700 °C for two hours.The above results showed that ?-CAF-K,Al is the excellent fiber with high strength and high flame resistance performance and further study will continue in the future..