Research On The Thermal Properties Of Alginate Fiber

In recent years,flammable synthetic fibers and natural fibers such as cotton fibers have been challenged as the increasing awareness of environmental protection and the increasing scarce of petroleum resources.Alginate fiber has a wide range of sources,renewable,green pollution-free and intrinsically flame-retardant and other excellent performance,and has been favored by domestic and foreign researchers.Since the performance of alginate fibers is affected by the G:M ratio,and the flame retardant effects of different metal ion alginate fibers are different.These problems need to be solved systematically.In this dissertation,Alginate-M(M=Cu2+,Ca2+)fibers were prepared by wet spinning process with different G:M sodium alginate as raw materials.Based on the limit oxygen index(LOI),thermogravimetric analysis(TG),and microcalorimetry(MCC),the mechanical properties,thermal stability,flame retardancy,and combustion characteristics of the Alginate-M fibers were characterized.The test results show that with the increase of G:M ratio,the mechanical properties,thermal stability and flame retardancy of Alginate-M fibers are improved.MCC test results show that the HRR of Alg-M fiber is lower than that of Alginate-H,indicating that the metal ion acts as a flame retardant,and the flame retarding effect of Alginate-Ca fiber is better than that of Alginate-Cu fiber.In order to explore the flame retardance mechanism of different metal ions,we used the gas chromatography-mass spectrometry pyrolysis instrument(PY-GC-MS)to characterize the thermal cracking products of the fibers.The results showed that the main pyrolysis products produced by Alg-Cu fiber(15)were more than that of Alg-Ca fiber(4)at 300°C;at 700°C,the Alg-Cu fibers were mostly ester macromolecules and Alg-Ca Fiber products are mainly aldehydes,ketones,acid small molecules.This also shows that the flame-retardant mechanism of Alg-Cu fibers and Alg-Ca Fiber is different.Cu2+ have a catalytic cracking effect on alginate macromolecules,making alginate macromolecules cleave to a greater degree at lower temperatures;and the flame retardance mechanism of Ca2+ on alginate macromolecules is reflected in the solidification phase retardation of carbonates.Combustion and deacidification reactions release the synergistic effect of carbon dioxide gas phase flame retardant.Graphene oxide(GO)has excellent mechanical properties,catalysis,thermal stability and flame retardancy.It is widely used in the reinforcement,toughening,and flame retardancy of composite materials.In order to improve the flame retardancy of Alg-Cu fibers,Alg-Cu/GO composite fibers were prepared.The mechanical properties,flame retardancy,thermal stability and thermal cracking products of the composite fibers were characterized and the flame retardant mechanism was discussed.The test results show that with the increasing of GO,the thermal stability and the flame retardant performance of the composite fiber are enhanced.When 5% GO was added,the HRR of the composite fiber was reduced to 42%.PY-GC-MS analysis showed that GO catalyzed the decomposition of Alg-Cu fibers at 300°C,more non-flammable gas or low thermal content small molecules were generated.We speculated that the flame retardant mechanism of GO on Alg-Cu fibers: when the fibers are burned,the GO in the fiber polymer matrix rapidly desorbed hydroxyl and carboxyl groups at high temperatures,releasing carbon dioxide,water and other small molecular gases,A dense continuous carbon layer is formed.This carbon layer can act as an insulating barrier to prevent heat transfer and material transfer,thereby improving the flame retardant properties of the composite fiber.