Formation and characteristics of the crystalline cellulose x modification of cellulose

Abstract

Abstract Previously reported experiments dealing with the formation of the new cellulose × modification in precipitates after treatment of cotton and wood pulp with strong hydrochloric acid are summarized and discussed in connection with results from a recent investigation where other swelling systems have been applied. It has been demonstrated that very pure precipitates of cellulose x may be obtained by means of treatment with phosphoric acid (84.5%) at 50°C. The hypothesis for the formation of the new modification has been discussed, and it is suggested that the necessary condition for the formation of cellulose x is swelling to such a degree that the complexes (C 6 H 10 O 5 ·4H 2 O·HCl) n and (C 6 H 10 O 5 ·2H 2 O·H 3 PO 4 ) n are obtained. The most probable unit cell for cellulose x, as judged from the x‐ray experiments, is one having the same dimensions as cellulose IV, but with different reciprocal positions of the corner and central cellulose chains in the lattice. The infrared spectrum of cellulose x lies between those of cellulose II and IV, and bears a somewhat closer resemblance to that of cellulose II.