Cotton Fibre Strength and Elongation
topic
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.
Role
Fibre strength directly determines the tensile performance ceiling for all downstream yarn and fabric products, with each unit increase in fibre tenacity translating to measurable improvements in yarn breaking strength, fabric tear resistance, and end-product durability.