Overview
ISO 21701:2025 - Textiles - Test method for accelerated hydrolysis of textile materials and biodegradation under controlled composting conditions of the resulting hydrolysate - specifies a laboratory method to evaluate the biodegradability of hydrolysates from textile materials. The method combines an accelerated hydrolysis (abiotic) step with a subsequent controlled composting (biotic) biodegradation test. Biodegradability is determined by measuring evolved carbon dioxide (CO2) using gas chromatography (GC) or non-dispersive infrared (NDIR) analysis and expressing results relative to the theoretical CO2 yield calculated from total organic carbon (TOC).
Key topics and technical requirements
- Scope: Applies to petroleum‑based, man‑made biodegradable textiles such as polyethylene terephthalate succinate, polycaprolactone, polypropylene carbonate, polybutylene succinate and related copolymers.
- Test principle: Perform accelerated hydrolysis under controlled temperature and humidity to generate a hydrolysate, then carry out small‑scale aerobic composting and monitor CO2 evolution to assess ultimate biodegradability.
- Measurement methods: CO2 quantification by gas chromatography (with suitable calibration and internal standards) or by NDIR; calculation of cumulative CO2 and percentage biodegradation against the theoretical CO2 (ThCO2) derived from TOC.
- Apparatus: environmental chamber (RH ±5 %, temperature tolerance ±1 °C), gel permeation chromatography (GPC) for molecular‑weight monitoring, composting vessels (1–5 L), air‑supply system, GC (FID) or NDIR measurement systems.
- Procedure elements: preparation of test material and inoculum, abiotic accelerated hydrolysis, biotic biodegradation test, periodic gas analysis, data calculation and validity criteria.
- Documentation: test report requirements include analytical method details, sampling intervals, flow rates (for NDIR), dates and any unusual observations.
- Caveat: ISO 21701:2025 is a laboratory method; claims on compostability or biodegradation must follow ISO 14855‑1 and appropriate certification-misleading claims are warned against in the standard.
Applications
- Product R&D and material screening for biodegradable textile fibers and polymer blends.
- Accredited testing laboratories performing biodegradability testing for technical dossiers.
- Sustainability teams and brand compliance groups assessing end‑of‑life behavior of man‑made fibers.
- Material scientists studying hydrolytic degradation, molecular‑weight loss and subsequent microbial mineralization.
- Regulatory or certification preparatory testing before full-scale compostability assessment.
Who uses this standard?
- Textile testing laboratories and contract testing services
- Fiber and polymer manufacturers (R&D and quality)
- Environmental test engineers and compostability assessors
- Certification bodies preparing for ISO 14855‑1 compostability protocols
- Academic researchers in polymer biodegradation and textile sustainability
Related standards
- ISO 14855‑1 - Ultimate aerobic biodegradability under controlled composting conditions (evolved CO2)
- ISO 13885‑1 - Gel permeation chromatography (GPC) using THF
- ISO 3071 - Determination of pH of aqueous extract (textiles)
- ISO 1628‑1 - Viscosity of polymers in dilute solution
Keywords: ISO 21701:2025, textiles, accelerated hydrolysis, biodegradation, composting, hydrolysate, gas chromatography, NDIR, biodegradability testing.
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