Fire–retardant viscose: its main element is cellulose,and internal macromolecules are format silicate molecular network and a lot of chemical combination water.
The physical and mechanical properties are similar with ordinary viscose fibers, its not only has a better hygroscopic and easy to dye, but also acid and alkali-resistance and moth-proofing [1].Fire-retardant viscose has good fire resistance performance (limiting oxygen index LOI values> 28%), ignited a long time,heat release rate, effective heat of combustion and smoke release ratio are lower than ordinary viscose fiber, structure of burning residue is combustion.
Experiment of fire-retardant：
1、Vertical Flammability Test：
Used to determine the burning breadth (carbonized area and damaged length ) after flame time、smoldering time of materials. The method is made a definite dimension specimen in prescriptive case burning with the fire twelve seconds, then remove the flame and determined the burning time, smoldering time, after flame time, according to provisions method to detect length (carbonized length)[5]. This is a basic method of testing standards, our GB5455-1997; strict standards applicable to all kinds of fabric test.
2、The Limit oxygen index method：
As the limit oxygen index method, means on the stipulated experimental condition, the minimum concentration of oxygen volume on the oxygen and nitrogen mixture gas which can keep the materials just burning,with the LOI said. Tests on the oxygen index tester.
Method is made a definite dimension specimen be placed on sample folder in the combustion cylinder, adjust oxygen and nitrogen with certain proportion, Use specific ignition lit specimen， burning certain time or damaged length from extinguish, At this time of oxygen,nitrogen flow from the table detected oxygen values, that is the LOI of sample [6]. Our standard GB5454-1997 Provisions sample just burning 2 minutes from extinguish or damaged length just needed oxygen for 40mm needed percentage of oxygen just as the LOI of the sample.