ON THE PARTIAL NITRATION OF RAYON STAPLE IN FIBROUS STATE

Abstract

To study the relation between the moisture regain and the heterogenity of the nitration process in the fibrous state, the effects of the composition of the nitrating mixture, time and temperature of reaction on the swelling at reaction, the nitrogen content of the product, its moisture regain etc, were determined.The results are as follows:(1) A carbon tetrachloride (or acetic acid)-acetic anhydride-nitric acid system was suitable to study the process because of its mild reaction and little damage to the fiber.(2) When the water content of the raw material exceeded 30%, the nitration was accelerated considerably.(3) The rate of nitration increased with higher temperature.(4) When this system was diluted over 1:9 with carbon tetrachloride, the nitration was retarded.(5) In the acetic acid-acetic anhydride-nitric acid system, less acetic anhydride gave higher swelling at the reaction and more rapid reaction.(6) Higher swelling at the reaction, which was derived from higher sample moisture etc., seems to result in lower moisture regain of the product at the same nitrogen content. It is suggested that the reaction proceeds macro-(fiber)-homogeneously and micro-(crystallite)-heterogeneously and that the hydroxyl groups in the amorphots region, which mainly absorbes the moisture, can be substituted selectively.