Self–smoothing Cellulosic Fabrics*

I The original invention of crease–resisting textiles took place just before the formulation of the chemical constitution and molecular structure of cellulose, but subsequent developments have taken place side by side. The conception of chain–molecules in varying degrees of lateral order is now generally accepted, but there are dangers of oversimplifying the picture of a network structure as solely comprising the crystallites and amorphous regions; insufficient attention is pa, id to the probable existence of a loose network having occasional junction points within the amorphous regions, as in the general theory of gel structures. These junction points may be increased in number and variety to form a: new network which is sufficiently entangled to impart properties of technical and commercial value. In the technology of the various processes, the relative proportions of the different types of cellulose, their accessibility and reactivity, are all important and may be controlled to some extent; sensitivity to degradation and embrittlement are also influenced. II– Of the large number of new effects which may be obtained by suitable entanglements of the molecular chains of cellulose, the most outstanding are associated with crease–recovery, both wet and dry. These and other properties may be stabilised and made durable through the use of certain chemical compounds such as thermosetting resins (phenol–formaldehyde, urea–formaldehyde, or melainine–formaldehyde), reaetant resins (bifunctional derivatives of imidazolidones and triazones), and linear reactants (formaldehyde, butanedioldiurethane. opoxy compounds, and glycols). III– Self–smoothing fabrics of cotton and ra. you require different amounts of reagent for a similar result, but the quantities are almost equal when calculated on the amorphous contents of the fibres. There is some agreement between the anomalous behaviour of cotton and rayon on drying and on addition of the self–smoothing finish; in both cases the effects may be attributed to molecular entanglements, the disruption of which causes a return to the original properties. With conventional chemical treatments the reticula, tiori is accompanied by resin–formed bonds, heat–formed hydrogen bonds, and the usual hydrogen bonds; thus there is a network within a network, giving increased elastic recovery but also increased, rigidity. The mechanical properties of the treated fibres may be influenced by the amount of accessible cellulose and hence by the relative number of heat–formed hydrogen bonds; the latter may be broken after treatment by a form of caustic conditioning or mercerising, but they may be prevented from forming when the curing stage occurs in steam. Many of the characteristics of the final product may be due to the proportions of normal hydrogen bonds, heat–formed hydrogen bonds, and cellulose–resin–cellulose bonds.