ISO 21701:2019

Overview

ISO 21701:2019 defines a laboratory test method to determine the biodegradability of hydrolysate produced from textile materials after accelerated hydrolysis, by measuring evolved carbon dioxide (CO2) with gas chromatography (GC). The method is intended for petroleum-based man‑made biodegradable textile materials (for example those made from polyethylene terephthalate succinate, polycaprolactone, polypropylene carbonate, polybutylene succinate or related copolymers). The procedure simulates intensive aerobic composting by combining an abiotic accelerated hydrolysis stage with a subsequent biotic composting stage to quantify mineralization of the hydrolysate.

Key topics and requirements

• Test principle: Accelerated hydrolysis (high temperature/humidity) to generate hydrolysate → controlled composting of hydrolysate → periodic CO2 measurement by GC to calculate biodegradation.
• Measurement and calculations: CO2 evolved is measured and expressed relative to the theoretical amount of CO2 calculated from measured total organic carbon (TOC); results include cumulative CO2, percentage biodegradation, and validity criteria.
• Apparatus and instrumentation:
  • Environmental chamber for hydrolysis (RH control ±5 %, temperature tolerance ±1 °C)
  • Gel permeation chromatography (GPC) for molecular-weight analysis
  • Composting vessels and air‑supply system (1–5 L typical)
  • Gas chromatograph with flame ionization detector (FID) and suitable calibration/internal standards (e.g., CO2/N2)
  • Analytical tools for dry solids, volatile solids and TOC
• Sample and inoculum:
  • Typical minimum test mass (~200 g) prepared as small pieces (max ~2 cm × 2 cm)
  • Compost inoculum requirements (sieved, well‑aerated municipal/green waste compost; target CO2 production and pH ranges specified)
• Controls and reporting: Positive control (TLC-grade cellulose) recommended; test report must document procedures, calculations, and validity checks.

Applications and users

• Textile manufacturers and product developers assessing biodegradability of petroleum‑based biodegradable fibres and fabrics.
• Third‑party testing laboratories performing standardized biodegradation testing for research, compliance, or product development.
• R&D teams optimizing polymer formulations or treatments to improve hydrolysis and biodegradability.
• Sustainability managers and compliance officers evaluating end‑of‑life behavior under controlled composting conditions.

Note: ISO 21701:2019 addresses biodegradability of the hydrolysate. For formal claims of biodegradation or industrial compostability of finished textile materials, testing per ISO 14855-1 is required.

Related standards

• ISO 14855-1 - Determination of ultimate aerobic biodegradability of plastics under controlled composting conditions (CO2 analysis)
• ISO 13885-1 - Gel permeation chromatography (GPC) guidance
• ISO 1628-1 - Viscosity measurement of polymers (relevant supporting methods)

Keywords: ISO 21701:2019, textiles, accelerated hydrolysis, biodegradation, composting, hydrolysate, gas chromatography, petroleum-based biodegradable fibres, TOC, GPC.