Overview
ISO 2007:2025 - "Rubber, unvulcanized - Determination of plasticity - Rapid‑plastimeter method" specifies a standardized laboratory procedure for rapidly measuring the plasticity of raw rubber and unvulcanized compounded rubber. The method is suitable for determining the plasticity retention index (PRI) referenced in ISO 2930. This sixth edition updates apparatus requirements and adds precision data (Annex A) from an interlaboratory study.
Key topics and requirements
- Scope: Applies to raw natural and synthetic rubbers and unvulcanized compounds; intended for rapid plasticity measurement and PRI determination.
- Principle: A disc‑shaped test piece is preheated while compressed to 1.00 mm, then subjected to a constant compressive force (100 N ± 1 N) for 15 s; the final thickness is the plasticity measure.
- Apparatus: A parallel‑plate plastimeter with heated, parallel platens (selectable small platen diameters: 7.30 mm, 10.00 mm, or 14.00 mm), thickness indicator (0.01 mm resolution), force application and timing devices, punch for producing ~13 mm diameter discs, and specified tissue/cigarette paper.
- Test specimen: Disc ≈13 mm diameter, thickness 3.4 mm ± 0.2 mm; prepare and condition samples per ISO 1795 and ISO 23529. Prepare three test pieces; median of the three results (in hundredths of a millimetre) is the plasticity number.
- Test conditions: Standard test temperature 100 °C ± 1 °C; platen movement to 1.00 mm completed within 2 s; pre‑heating 15 s, test force period 15 s ± 0.2 s.
- Calibration & verification: Calibrate spring force and timing per ISO 18899; verify instrument using standard materials (e.g., standard butyl or NIST reference NBS‑388).
- Precision: Annex A reports interlaboratory repeatability and reproducibility (example ranges: r ≈ 0.2–0.7 units, R ≈ 2.4–3.1 units; relative reproducibility ≈ 7.5–9.7% for tested materials).
- Test report: Must include sample ID and preparation, reference to ISO 2007:2025, platen size, test temperature, plasticity number, and date.
Applications and users
- Who uses it: Rubber testing laboratories, quality control (QC) teams in rubber manufacturing, compounders, material development laboratories, and third‑party testing/inspection bodies.
- Practical uses:
- Rapid QC acceptance testing for raw rubber and unvulcanized compounds.
- Measuring baseline plasticity and assessing plasticity retention index (PRI) for aging/stability studies.
- Supporting formulation control and batch consistency in tire, hose, seal and other rubber product manufacturing.
- Instrument verification and interlaboratory comparisons.
Related standards
- ISO 2930 - Plasticity retention index (PRI) procedures (method linkage)
- ISO 1795 - Sampling and preparative procedures for raw rubber
- ISO 23529 - Preparing and conditioning test pieces
- ISO 18899 - Guide to calibration of test equipment
Keywords: ISO 2007:2025, rapid‑plastimeter, rubber plasticity, plasticity number, PRI, unvulcanized rubber, plastimeter test method, rubber testing, QC.