From Selection of Polymeric Materials: How to Select Design Properties from Different Standards

2.3 Comparison of ASTM and ISO Mechanical Test Standards

The ISO 10350:1993 test standards facilitate the means to obtain a particular set of properties, test methods, and SI reporting units as generally acceptable European material specifications to characterize and describe polymeric materials. ISO testing enables comparison of the properties of the polymeric materials produced around the world, as long as the properties are reported using the ISO standards.

The ISO 10350:1993 mechanical test standards fall below expectations for delivering uniform global mechanical test standards. ISO has changed several mechanical test procedures, specimen geometries, and testing equipment. The ISO 10350:1993 method does not describe all the mechanical characteristics for polymeric materials. In contrast, the ASTM mechanical properties are described in more detail, they are more realistic to the applications, and they comply with the requirements of the plastics industry. ASTM mechanical test standards have performed well much longer than ISO standards.

To illustrate this point, Table 2.4 compares the most important ASTM mechanical testing procedures reported in both units (US and SI), and ISO test methods only reported in SI units.

Table 2.4: ASTM and ISO Comparison of Mechanical Test Standards

ISO Number 10350:1993

Plastic Test Description

ASTM Standards

ASTM (US units)

ASTM (SI units)

ISO Standards

ISO (SI units)

2.

Mechanical Properties

2.1

Tensile modulus

D-638

psi

MPa

527-1 & -2:1993

MPa

2.2

Yield stress

D-638

psi

MPa

527-1 & -2:1993

MPa

Tensile stress @ fiber glass TD

psi

MPa

Mpa

2.3

Yield strain

D-638

%

%


Products & Services
Elastomers and Rubber Compounds
Elastomers and rubber materials are characterized by their high degree of flexibility and elasticity (high reversible elongation or resilience).
Calibration and Test Weights

Calibration weights and mass standards have a certified mass that is traceable to national or international laboratory standards. Mass standards calibrate scales and weighing instruments and help evaluate material or mechanical properties.

Deflectometers and Extensometers
Deflectometers and extensometers are used to indicate the deformation of material while it is subjected to stress.
Viscosity Standards and Reference Fluids
Viscosity standards and reference fluids are oils, fluids, greases, or gels with stable and verified viscosity values and flow properties for calibration of viscometers, rheometers, and other standards.
Mechanical Testing Services
Mechanical testing is the process of physically applying a stimulus to a mechanical system. These stimuli can be displacements, heat, forces, pressures or other physical stress that may be placed on the object being tested. Mechanical testing can be used to verify the key performance attributes of the material, part or complete mechanical system in question.

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