| Popis: |
Native cotton yarn reacts rapidly with phosphoryl chloride in N,N-dimethylformamide to produce highly chlorinated cellulose (degree of substitution of 0.5 or greater), phosphorylated cellulose, and cellulose formate. The ratio of chlorination to phosphorylation was readily controlled by varying the concentration of phosphoryl chloride in N,N-dimethylformamide. Reaction variables studied were the reagent concentration, reaction temperature, and reaction time. The effect that each of these variables has on the tensile and flammability properties of the resultant yarns was investigated. Yarns containing large proportions of chlorine have high tensile-strength and are unusually extensible, whereas yarns containing phosphorus have high flame-resistance. A mechanism for the selective chlorination or phosphorylation of the cotton cellulose is advanced. |
