ISO 21306-1:2019

Overview

ISO 21306-1:2019 defines a standardized designation system and basis for specifications for unplasticized poly(vinyl chloride) (PVC‑U) moulding and extrusion materials. It sets out how to identify PVC‑U thermoplastic compositions (homopolymers, copolymers, chlorinated PVC and suitable blends) that contain at least 50% vinyl chloride by mass, and applies to materials supplied as powder, granules or pellets. The standard excludes cellular plastics and does not provide engineering, performance or processing data.

Key topics and technical requirements

• Designation structure: A modular model combining a descriptor, identity (standard number) and an “object particular” block subdivided into five data blocks for unambiguous material identification.
  • Block 1: PVC‑U identification using the symbol from ISO 1043‑1.
  • Block 2: Fills/ reinforcements (not included in Part 1).
  • Block 3: Intended application/method (position 1) and important additives/properties (positions 2–8) using letter codes (e.g., E = extrusion, M = injection moulding, G = granules, N = natural).
  • Block 4: Designation properties - coded ranges for:
    • Vicat softening temperature (three‑digit number code),
    • Impact strength (Charpy notched) (two‑digit number code),
    • Modulus of elasticity (letter + two‑digit code; T prefix used for tensile modulus).
  • Block 5: Optional extra requirements to turn a designation into an application‑specific specification.
• Test methods: Part 1 references ISO 21306‑2 for specimen preparation and determination of Vicat, Charpy and modulus values.
• Important notes: Identical designations do not necessarily guarantee identical performance; Part 1 is a classification and designation framework, not a source of processing or engineering data.

Practical applications

• Use ISO 21306‑1 to:
  • Standardize material descriptions in procurement documents, specifications and datasheets.
  • Communicate required property ranges (Vicat, impact, modulus) concisely between suppliers, compounders and OEMs.
  • Create traceable material IDs for quality control in extrusion and moulding operations.
• Typical industries and uses:
  • Pipes, profiles and fittings (extrusion),
  • Injection‑moulded components,
  • Building products and general PVC‑U fabricated items where reproducible material selection is required.

Who should use this standard

• Material suppliers and compounders of PVC‑U,
• Product designers and OEMs specifying thermoplastic materials,
• Quality engineers, purchasers and testing laboratories involved in plastics compliance and procurement.

Related standards

• ISO 21306‑2 - specimen preparation and test methods for the designation properties.
• ISO 1043‑1 - polymer identification symbols and abbreviated terms.

Keywords: ISO 21306-1, PVC-U, unplasticized poly(vinyl chloride), designation system, Vicat softening temperature, Charpy notched impact, modulus of elasticity, material specification, plastics standards.