Mechanisms of degradation of cotton and effects of mercerization‐stretching upon the course of these mechanisms, VI. Structural differences between scoured cotton and slack mercerized‐stretched cottons

Scoured ply cotton yarn (substrate I) was slack mercerized (substrate II) and slack mercerized followed by stretching to 94% (substrate III) and 103% of original length (substrate IV). These substrates were given an acid pretreatment (0.5 N HCl, 60°C, 15 min). The four substrates and their corresponding HCl‐treated substrates (substrates I‐H, II‐H, III‐H and IV‐H) were reacted under similar conditions with N,N‐diethylaziridinium chloride to yield diethylaminoethyl (DEAE)‐cottons. In addition, DEAE‐cottons of substrates I, I‐H, II and II‐H were hydrolyzed with 0.5 N HCl at 80°C for 0.5, 1, 2, 3, 5 and 7 h and the ratio of substituents in the D‐glucopyranosyl units of these DEAE‐cottons as well as in those of DEAE‐hydrocelluloses were determined. It was found that there is a considerable difference between the reactivity of scoured cotton and slack mercerized‐restretched cottons. This was interpreted in terms of differences in the microstructure between the substrates in question, which in turn, are reflected on availability, accessibility and state of order of the cellulose hydroxyls in the scoured and mercerized cottons. Nitrogen‐, chemical, microscopical and X‐ray analyses were used to assess the structural differences among the substrates.