Meet the Tensiles: Strength, Modulus & Elongation
If you’re selecting a plastic for an application, tensile properties are a key part of the decision. Tensile refers to a material’s capability to be stretched or drawn out—essentially a measure of ductility. Standardized methods include ASTM D638 (U.S.) and ISO 527‑2 (EU/Asia). Tests are performed with a tensometer pulling a dog‑bone specimen under controlled temperature and conditioning until break, producing a stress–strain curve used to characterize material behavior.
The following three tensile metrics are commonly used to understand a plastic’s potential performance:
Tensile Modulus (Young’s Modulus)
The tensile modulus measures a material’s resistance to elastic deformation (the straight-line portion of the stress–strain curve up to the proportional limit). A higher modulus indicates a more rigid material. Values are expressed in psi or MPa.
Tensile Strength at Yield / Ultimate Tensile Strength
Yield is the stress a material can withstand without permanent (plastic) deformation. On the stress–strain curve, the Ultimate Tensile Strength (UTS) appears at the end of strain hardening and onset of necking—where the curve’s slope reaches zero. Practically, think of adding weight to a cable: the point where it stretches beyond recovery is the UTS.
Tensile Elongation at Break
Elongation is measured by pulling the specimen until fracture. It’s reported as the percent change in length from the original gauge to the fracture point. This is a comparative indicator of ductility vs. brittleness.
Reading Data‑Sheet Values
Because tensile properties vary with specimen preparation and environment (e.g., temperature), test parameters must follow the relevant standard (ASTM D638 or ISO 527‑2). Understanding how to read these values on a data sheet is critical to selecting the optimal plastic for your application.
Tip: When comparing materials, confirm the test standard, conditioning, and specimen type are consistent—otherwise comparisons can be misleading.
Figures & Diagrams
Contact Port Plastics
Have questions about selecting materials for tensile performance? Contact your local Port Plastics sales office for expert guidance on semiconductor and plastics applications.
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