ISO 17278:2020 PDF

Overview

ISO 17278:2020 specifies a laboratory test method for measuring the gel content of technically specified rubber (TSR) - raw natural rubber processed from Hevea brasiliensis. The method determines the insoluble (gel) fraction by dissolving TSR in toluene, separating the insoluble material by centrifugation, drying and weighing the residue. Results are reported as a percentage gel content (rounded to one decimal place).

Key topics and requirements

• Principle: dissolve a defined mass of TSR in toluene, allow extraction, centrifuge to separate insoluble gel, remove solvent, dry precipitate and calculate gel content as a percentage of the original sample mass.
• Reagents: analytical-grade toluene (primary solvent) and acetone (for rinsing precipitate).
• Apparatus & accuracy:
  • Laboratory centrifuge: 14 000 r/min (recommended) or minimum 8 000 r/min with extended time.
  • Screw-cap centrifuge tubes (≥30 cm3) able to withstand >110 °C.
  • Balance accurate to ±0.1 mg and weighing containers to ±1 mg.
  • Oven capable of 110 °C ±10 °C and a desiccator.
• Test conditions & procedure:
  • Sample ratio: typically 0.1 g TSR per 30 cm3 toluene.
  • Extraction: stand 16–20 h at (25 ± 2) °C in the dark.
  • Centrifugation: 14 000 r/min for 2 h (or 8 000 r/min for 6 h).
  • Drying: precipitate dried at 110 °C for 1 h; repeat weighings until mass change