ISO 7270-1:2020

Overview

ISO 7270-1:2020 specifies a qualitative method for the identification of polymers (single polymers and polymer blends) in raw, vulcanized or unvulcanized rubber compounds using pyrolytic gas‑chromatographic methods (pyrolysis‑GC). The standard defines how to produce and interpret pyrograms (pyrolysis‑gas chromatographic patterns) obtained under the same analytical conditions and is explicitly not intended for quantitative analysis. It presumes familiarity with gas chromatography principles.

Key technical topics and requirements

• Scope and principle: Pyrolyse a small test portion and analyze pyrolysis products by gas chromatography to generate a pyrogram; identify polymers by comparing retention times and characteristic hydrocarbons with reference pyrograms.
• Applicability & limitations:
  • Primarily for single polymers; applicable to blends when characteristic hydrocarbons are present.
  • Some distinctions are not possible (e.g., natural vs synthetic polyisoprene, different chlorinated polyethylene types, certain halogenated variants).
  • Blends of NR/IR, BR, IIR and SBR can generally be identified, but blends containing SBR + BR are an exception.
• Reagents & sample prep:
  • Use analytical‑grade solvents (examples: acetone, methanol, methyl ethyl ketone) for extraction following ISO 1407 to remove additives/oil extenders.
  • Carrier gases: nitrogen or helium; detector gas for FID: hydrogen + air.
• Apparatus & operating ranges:
  • Pyrolysis devices: micro‑furnace, Curie‑point, or platinum‑filament pyrolysers.
  • Typical pyrolysis temperatures: 400–800 °C for micro‑furnace/Curie‑point; 800–1 200 °C for platinum‑filament.
  • Gas chromatographs with FID or TCD are suitable; selective detectors (ECD, FPD, AED) and mass spectrometer (MS) can aid identification.
  • Test portion masses: typically 0.1 mg to 5 mg for reproducibility.
• Data interpretation & reporting:
  • Identify polymers by main peak retention times and characteristic pyrolysis hydrocarbons (e.g., isoprene, styrene, butadiene).
  • Test report must include sample ID, pyrolysis device and temperature, GC conditions, and interpretation.

Practical applications

• Quality control and incoming‑material verification in rubber manufacturing.
• Failure analysis and root‑cause investigations when polymer type affects performance.
• R&D and formulation development to confirm polymer compositions in blends and compounds.
• Forensic and regulatory testing where polymer identification is required.

Who should use this standard

• Analytical chemists and laboratory technicians in rubber testing labs.
• Rubber product manufacturers, compounders, and quality assurance teams.
• Research institutions and forensic laboratories performing pyrolysis‑GC.

Related standards

• ISO 1407:2011 - Rubber - Determination of solvent extract (extraction procedure referenced).
• ISO 1629:2013 - Rubber and latices - Nomenclature (polymer grouping referenced).
• Other parts of the ISO 7270 series for complementary pyrolysis‑GC methods.