ISO 21306-2:2019

Overview

ISO 21306-2:2019 - Plastics - Unplasticized poly(vinyl chloride) (PVC‑U) moulding and extrusion materials - Part 2 - specifies how to prepare test specimens and determine the physical, thermal, mechanical and electrical properties of PVC‑U materials for moulding and extrusion. It defines handling, pre‑treatment, specimen preparation (compression moulding and machining/punching) and conditioning to ensure reproducible, comparable test results. Test data are to be reported in accordance with ISO 10350‑1 and material designation follows ISO 21306‑1.

Key topics and requirements

• Specimen preparation
  • Pre‑plasticization on a two‑roll mill and production of compression‑moulded plates (conditions given in the standard).
  • Machining or punching of specimens from compression plates per ISO 2818.
  • Use of the code letter “Q” to indicate compression‑moulded specimens.
• Conditioning
  • Standard conditioning at 23 °C ± 2 °C and 50 % ± 5 % RH for at least 16 hours; a minimum of 24 hours is recommended before electrical tests.
  • Emphasis on controlling thermal history and internal stress because these affect mechanical, thermal and environmental stress‑cracking behaviour.
• Test methods and presentation
  • Mechanical: tensile (ISO 527 series), flexural (ISO 178), impact Charpy (ISO 179), tensile‑impact (ISO 8256), creep (ISO 899‑1).
  • Thermal: heat‑deflection (ISO 75‑1/2), Vicat softening (ISO 306), flammability/oxygen index (IEC 60695‑11‑10, ISO 4589).
  • Electrical: permittivity (IEC 60250), resistivity (IEC 62631‑3‑1/3‑2), dielectric strength (IEC 60243‑1).
  • Test conditions, specimen dimensions and reporting formats are specified (refer to the tabulated test matrix in the standard).

Practical applications

• Ensures reproducible comparative data for material suppliers, compounders and product designers working with PVC‑U for injection moulding and extrusion.
• Supports material specification, quality control and product development by providing standardized procedures for:
  • Selecting PVC‑U grades for pipes, window profiles, fittings, housings and electrical insulation components.
  • Evaluating mechanical strength, stiffness, impact resistance, thermal performance and electrical insulation properties.
  • Generating intrinsic material data for data sheets and regulatory or procurement specifications.

Who should use this standard

• Material manufacturers and compound formulators producing PVC‑U.
• Test laboratories performing standardized physical, thermal and electrical testing.
• Product designers, specifiers, certification bodies and quality engineers requiring comparable material property data.

Related standards

• ISO 21306‑1 (designation/specification basis)
• ISO 10350‑1 (presentation of intrinsic properties)
• ISO 291 (conditioning atmosphere)
• ISO 293, ISO 2818, ISO 527, ISO 178, ISO 179, ISO 306
• IEC 60250, IEC 62631‑3‑1/3‑2, IEC 60243‑1, IEC 60695‑11‑10

Keywords: ISO 21306‑2:2019, PVC‑U, unplasticized poly(vinyl chloride), test specimens, compression moulding, conditioning, mechanical properties, electrical properties, material characterization.