ISO 5794-1:2022

Overview

ISO 5794-1:2022 - Rubber compounding ingredients - Silica, precipitated, hydrated - Part 1: Non-rubber tests specifies laboratory methods to characterize precipitated hydrated silica used as a rubber compounding ingredient. The standard defines sampling, test formulation, mixing procedure (for styrene‑butadiene rubber formulations), methods to determine physical and chemical properties of silica, and the required contents of a test report. It is intended for quality control, specification and product development of precipitated silica for the rubber industry.

Key topics and technical requirements

• Scope and sampling
  • Sampling is carried out in accordance with ISO 15528.
• Test matrix (properties and test methods)
  • Silica content (ignited sample) - ISO 3262-19:2021
  • Colour - ISO 3262-1:2020
  • Residue on sieve (45 µm; powder and other forms) - ISO 3262-19:2021 / ISO 787-18
  • Volatile matter (loss on heating at 105 °C) - ISO 787-2
  • Density - ISO 787-10
  • Loss on ignition at 1 000 °C - ISO 3262-1:2020
  • pH of slurry - ISO 787-9
  • Water‑soluble matter - ISO 787-8
  • Total metals: copper, manganese, iron - normative Annexes A–C (acid digestion and AAS)
  • Specific surface area - Annexes D and E (including multipoint nitrogen adsorption / BET)
  • Granule size distribution - Annex F
  • CTAB surface area - Annex G
• Annex H (informative) provides classification of silicas and typical properties.
• Test report requirements (Clause 6) - must reference ISO 5794-1 and include identification, all measured results (14 specified items, including silica content, CTAB and BET surface areas, granule distribution, metal contents, etc.), deviations and unusual observations, and test date.
• Safety - users must follow normal laboratory practice; some methods (e.g., HF digestion) require specific safety measures.

Applications and users

Who uses ISO 5794-1:2022:

• Silica manufacturers - to certify product quality and provide standardized data to customers.
• Rubber compounders and tire manufacturers - for selecting silica grades and ensuring consistent compounding performance with styrene‑butadiene rubber.
• Independent testing and QA laboratories - to perform accredited analyses and produce comparable reports.
• R&D teams - for material characterization during product development and troubleshooting.

Practical benefits:

• Ensures consistent, comparable property data for supply chain specification.
• Supports formulation decisions by providing standard surface area, particle size and impurity data relevant to reinforcement and cure behavior in rubber compounds.

Related standards

• ISO 5794 series (other parts)
• ISO 3262-19:2021 (precipitated silica test methods)
• ISO 18852 (multipoint nitrogen surface area)
• ISO 15528 (sampling)
• ISO 787 series (general methods for pigments and extenders)

Keywords: ISO 5794-1:2022, precipitated hydrated silica, rubber compounding ingredients, CTAB surface area, BET surface area, granule size distribution, total metal content, silica characterization, styrene-butadiene rubber.