Elongation at Break
Elongation at break is the percentage extension of a specimen relative to its original gauge length at the moment of rupture. It is determined in a tensile test to ISO 37 (elastomers), together with force at break.
Normative position:
- EN 455-2 specifies dimensions and force at break for medical single-use gloves (9.0 N sterile surgical, 6.0 N latex and nitrile, 3.6 N thermoplastic materials). It sets no minimum for elongation.
- Binding elongation limits appear in the US standards: ASTM D3578 requires at least 650 % before ageing for latex examination gloves; ASTM D6319 requires at least 500 % for nitrile.
- For PPE protective gloves, elongation is not a separate performance parameter; EN 388 values apply instead.
Practical significance: high elongation means the glove deforms considerably before it fails, improving fit and comfort and reducing the risk of sudden tearing under shock loading. Force at break and elongation are always assessed together: a material with high breaking force but low elongation tears more readily under abrupt strain than a more extensible one.
Frequently asked questions
Does EN 455-2 specify a minimum elongation at break?
No. EN 455-2 specifies dimensions and force at break, not elongation. Where elongation values are needed as a requirement, ASTM standards apply: ASTM D3578 requires at least 650 % for latex examination gloves and ASTM D6319 at least 500 % for nitrile, in each case before ageing.
How is elongation at break measured?
In a tensile test to ISO 37: a standardised specimen is stretched until rupture. Elongation at break is the percentage increase in length relative to the original gauge length at the moment of rupture, measured together with force at break.
Why are force at break and elongation assessed together?
They describe different aspects of load capacity. A glove with high breaking force but low elongation fails sooner under abrupt loading than a more extensible material. Only the combination of both values describes the mechanical behaviour completely.