Cotton Fibre Strength and Elongation

Cotton fibre bundle strength is measured by HVI (ASTM D2256) at 1/8 inch gauge length on 1g fibre bundles, reporting tenacity in g/tex (cN/tex). Upland cotton strength ranges 26–34 g/tex (average 29–30 g/tex), ELS varieties 38–50 g/tex. Individual fibre breaking tenacity (AFIS/Stelometer) is 20–45 cN/tex at 3.2 mm gauge. Elongation at break ranges 5.0–9.0% for upland and 6.0–11.0% for ELS. Specific work to rupture (toughness) is 1.5–2.5 cN·cm/tex. Fibre strength is primary determinant of yarn strength: yarn tenacity correlates with fibre strength at r² = 0.85–0.95. Each 1 g/tex increase in fibre strength produces 0.6–0.9 g/tex increase in ring-spun yarn strength at Ne 30. Moisture regain of 7–8.5% increases strength by 10–20% (wet strength > dry strength) due to inter-chain hydrogen bond reformation in wet cellulose. USDA premium for strength >34 g/tex (upland) is $0.02–0.05/lb.