Para-Aramid Properties and Performance
topic
Kevlar 29 (standard): tenacity 2.9 GPa, modulus 70 GPa, elongation 3.6%, density 1.44 g/cm³. Kevlar 49 (high modulus): tenacity 3.0 GPa, modulus 112 GPa, elongation 2.4%. Kevlar 129 (ballistic): tenacity 3.4 GPa, modulus 90 GPa. Common properties: negative coefficient of thermal expansion (-2 to -6 × 10⁻⁶/K axially), thermal decomposition >500°C, excellent cut resistance (5× steel wire of same weight), poor UV resistance (15-20% strength loss per year), moisture regain 4-7%, and poor compressive strength (20-30% of tensile).
Role
Exceptional tensile properties combined with low density (specific strength 2000+ MPa/(g/cm³) vs. steel 130) enable lightweight ballistic protection and reinforcement, while limitations (compression weakness, UV sensitivity, creep) require design considerations and protective measures.