ISO 1183-1:2025

Overview

ISO 1183-1:2025 defines standardized laboratory methods to determine the density of non‑cellular plastics. It covers three accepted procedures - the immersion method (Method A), the liquid pycnometer method (Method B) and the titration method (Method C) - applicable to void‑free moulded or extruded articles as well as powders, flakes and granules. The standard updates and replaces ISO 1183-1:2019 and adds clarifications on temperature control, buoyancy corrections and specimen volume calculations.

Key technical topics and requirements

• Scope and applicability: Density measurement for void‑free solid plastics, powders, granules, flakes and small pieces of finished parts.
• Methods
  • Method A - Immersion method: For solid, void‑free specimens (except powders). Requires an analytical balance (precision ±0.1 mg), immersion vessel (≥50 mm diameter), specimen holders or suspension wires and optional pycnometer/sinker.
  • Method B - Liquid pycnometer method: For particles, powders, flakes, granules or small pieces using a liquid pycnometer to obtain specimen volume by displacement.
  • Method C - Titration method: For plastics in any void‑free form using a liquid system suitable for the material; Annex A lists recommended liquid systems.
• Apparatus and measurements: Temperature measuring devices accurate to 0.5 K, suspension wires (≤0.5 mm for some uses; specimen holder wires ≤0.8 mm), thermostatted baths, and calibrated pycnometers where applicable.
• Immersion liquids: Deaerated, freshly distilled or deionized water is preferred; liquids may contain up to 0.1% wetting agent if needed. Liquids must not react with the specimen.
• Conditioning and atmosphere: Test atmosphere per ISO 291 class 2; temperature requirements for immersion liquid and air are specified. Buoyancy in air is addressed in the updated formulae and Annex B (now normative) for air density calculation.
• Supporting information: Annex C (informative) provides specimen volume calculation for immersion tests; Annex D explains formula derivations; Annex E provides precision data.

Practical applications and users

ISO 1183-1:2025 is used by:

• Quality control and testing laboratories for routine plastics density testing
• Materials scientists and R&D teams monitoring composition or structural changes
• Manufacturers validating material uniformity, batch consistency and specifications
• Certification bodies and contract testing organizations requiring traceable density data

Density is commonly used to detect changes in composition, processing defects or to verify material identity and uniformity. The standard emphasizes that specimen preparation can affect results and that preparation details should be recorded in material specifications.

Related standards

• ISO 291 - Standard atmospheres for conditioning and testing
• ISO 472 - Plastics - Vocabulary
• ISO 80000-4 - Quantities and units (referenced for terms)

Keywords: ISO 1183-1:2025, density of plastics, immersion method, liquid pycnometer, titration method, plastics density test, non‑cellular plastics, plastic materials testing.