ISO 37:2024

Overview

ISO 37:2024 - seventh edition - specifies a standardized laboratory method to determine the tensile stress–strain properties of vulcanized and thermoplastic rubbers. The document defines how to prepare and condition standard test pieces (dumbbells and rings), the required apparatus and calibration, the test procedure using a tensile‑testing machine at constant traverse rate, data calculation and expression of results, and reporting. Measured properties include tensile strength, elongation at break, stress at a given elongation, elongation at a given stress, and where applicable for some thermoplastic rubbers, stress and elongation at yield.

Key Topics and Requirements

• Scope and definitions: Clear definitions of tensile stress, elongation, tensile strength (Smax, Sb), elongation at break (Eb), yield point and related terms used in tensile testing.
• Test pieces: Requirements for dumbbell and ring specimens, their preparation, marking, measurement and comparison of groups of test pieces.
• Apparatus: Specification of equipment such as dies/cutters, thickness and cone gauges, and a tensile‑testing machine with constant rate of traverse. A test rig for ring specimens is also covered.
• Calibration and conditioning: Added calibration schedule and references to calibration guidance (ISO 18899). Conditioning of samples and timing between vulcanization and testing are specified to ensure reproducible results.
• Procedure and measurement: How to stretch specimens, record force and elongation, and compute stress using the original cross‑section; separate calculation methods for dumbbells and rings.
• Precision and reporting: Statistical precision guidance, required test report content, and annexes on precision data and calibration schedules.

Practical Applications and Users

Who uses ISO 37:2024:

• Material and product quality control laboratories
• Rubber and elastomer manufacturers and compounders
• R&D and formulation teams validating mechanical performance
• Suppliers and purchasers establishing material specifications
• Certification bodies and test houses performing compliance testing

Typical applications:

• Verifying tensile strength and elongation for product release and acceptance
• Comparing formulations or suppliers for mechanical performance
• Supporting specifications for seals, hoses, belts, gaskets, footwear and other rubber goods
• Generating data for design, failure analysis and regulatory documentation

Related Standards

• ISO 5893 - Specification for tensile test machines (constant rate of traverse)
• ISO 18899 - Guide to calibration of test equipment
• ISO 23529:2016 - General procedures for preparing and conditioning test pieces

Keywords: ISO 37:2024, tensile stress–strain, vulcanized rubber, thermoplastic rubber, tensile test, tensile strength, elongation at break, dumbbell test pieces, ring specimens, calibration, test report.