Full definition
The maximum stress (force per unit cross-sectional area) that a rubber specimen can sustain before breaking, expressed in megapascals (MPa) or psi. Measured per ASTM D412 (dumbbell or ring specimens pulled at 500 mm/min) or ISO 37. Tensile strength is a primary mechanical property used to characterize rubber compounds and assess quality. Typical values by elastomer type (with reinforcing carbon black): NR 25-32 MPa (highest of general rubbers due to strain crystallization), SBR 10-25 MPa, EPDM 10-20 MPa, NBR 10-25 MPa, neoprene CR 15-25 MPa, silicone VMQ 5-12 MPa (lowest), FKM 10-17 MPa, polyurethane PU 30-70 MPa (highest of all rubbers). Factors increasing tensile: higher carbon black loading (up to optimum), finer particle CB (N110 > N330 > N660), higher cross-link density (up to optimum), and strain-crystallizing polymers (NR). Tensile decreases with aging, heat exposure, and chemical attack. Per ASTM D412 and ISO 37. Tested at 23 ± 2°C. Often reported alongside elongation at break and modulus at 100/200/300% elongation. Minimum of 3 specimens averaged per ASTM D412.