8—MECHANICAL PROPERTIES OF CHEMICALLY MODIFIED COTTONS

Abstract

The mechanical properties of certain chemically modified cotton textiles studied in considerable detail mostly at the Southern Utilization Research and Development Division are summarized, Properties studied include breaking strength, yarn knot strength, tearing strength (Elmendorf). ultimate elongation, average tensile and flexural stiffness (modulus), toughness index (work of rupture), frictional behaviour, creep, elastic recovery, resilience and abrasionresistance (flat and flex). Chemical modifications have included many types, but only those which increase the weight of the cellulose molecule through substitution of the hydroxyl groups are included in the present report. Among these are substitution with acetyl, cyanoethyl, carboxymethyl, carboxyethyl (β-propiolactone) and benzyl groups. The changes in various mechanical properties are related to type of product (fibre, yarn or fabric), degree of substitution, conditions imposed during treatment and construction of the textile. The ‘dilution’ effect, due to group weight increase of the cellulose molecules, on such properties as strength, stiffness and work of rupture is considered. Some interpretations of the results are made in terms of fine structure.