Cellulose phosphorylation with a mixture of orthophosphoric acid and ammonium polyphosphate in urea medium

Cellulose samples with various extents of structural ordering (native cotton cellulose and mercerized cellulose) were phosphorylated with a mixture of orthophosphoric acid and ammonium polyphosphate in a urea medium. The phosphorus content and ion-exchange capacity of phosphorylated mercerized cellulose are higher than those of the initial natural polysaccharide phosphorylated under the same conditions. Modification of the glucopyranose rings of cellulose mainly occurs in amorphous regions of the polymer. The maximal rate of thermal degradation of cellulose phosphates is considerably lower than that of the initial polymers, and the degradation rate maximum is observed at 238-245A degrees C, in contrast to the main process of dehydration and carbonization of the initial materials, occurring at 330-340A degrees C. The results obtained can be used for preparing ion-exchange sorbents and fireproof fabrics with preset properties.