ISO/TS 21237:2020

Overview

ISO/TS 21237:2020 - "Nanotechnologies - Air filter media containing polymeric nanofibres - Specification of characteristics and measurement methods" defines which physical and structural characteristics of polymeric nanofibre layers on filter substrates should be measured and how to measure them. The technical specification covers both mandatory and optional characteristics, prescribes appropriate measurement techniques, and provides reporting templates (Annex B and C). It does not address health & safety characteristics or application-specific performance tests (e.g., particle removal efficiency or pressure drop), which are covered by other standards.

Key Topics

• Scope and purpose
  • Specifies characteristics to be measured for air filter media containing polymeric nanofibres deposited on substrates.
  • Aims to standardize communication between sellers and buyers and support trade.
• Mandatory characteristics
  • Fibre diameter - measured by SEM or FESEM (TEM as alternative). Recommended ~100 diameter data points; report histogram, median and standard deviation (nm).
  • Morphology - SEM/FESEM images of surface morphology (TEM, AFM or STM as alternatives); magnification scale required.
• Optional characteristics
  • Specific surface area - gas adsorption methods.
  • Chemical composition/content - FTIR, UV‑Vis, Raman, GC, HPLC, spectrophotometry.
  • Thermal stability - TGA (thermogravimetric analysis).
  • Crystalline structure / crystallinity / mean crystallite size - XRD, DSC, TEM/SAED; XRD is primary for crystalline properties.
• Measurement and reporting
  • Test specimens combine nanofibre layer(s) and substrate.
  • Measurement methods and results formatting are detailed; informative annexes include typical structures and example test report formats.

Applications

ISO/TS 21237:2020 is practical for:

• Filter manufacturers developing nanofibre-coated nonwovens or substrates.
• Materials scientists and R&D labs characterizing polymeric nanofibres (diameter, morphology, crystallinity).
• Independent test laboratories performing standardized measurement and preparing vendor/buyer reports.
• Procurement and quality teams who require standardized data from suppliers to compare nanofibre media.
• Regulatory and standards organizations coordinating technical specifications for nanotechnology-based filtration products.

Typical application areas include HVAC systems, cleanrooms, respiratory protection, industrial dust collectors, and turbine inlet filters where nanofibre-enhanced media are used to improve filtration efficiency while minimizing pressure drop.

Related Standards

• ISO/TS 21237:2020 focuses on material characteristics and measurement methods. For performance testing (pressure drop, particle removal efficiency) and health & safety considerations, use the relevant published standards for air filter performance (application-specific filtration test methods). ISO/TC 229 (Nanotechnologies) provides related nomenclature and technical context.