Overview
ISO 6775:2024 - Plastics - Plastics identification using Raman spectrometric methods - defines a standardized, qualitative approach for identifying plastic materials in their original form using Raman spectroscopy. The standard covers procedures for single-layer and multi‑layer film plastics, including instrument calibration, spectral acquisition, and spectrum analysis. It is a non‑destructive method that usually requires no sample preparation and relies on matching Raman fingerprints to reference spectra.
Key topics and technical requirements
- Scope: Identification of general plastics, multi‑layer films, particles, powders and coloured or opaque samples in their original form.
- Principle: Inelastic light scattering produces a Raman spectrum that serves as a molecular fingerprint for polymer identification.
- Apparatus:
- Stable monochromatic laser sources (recommended wavelengths include 532 nm, 638 nm, 785 nm, 1 064 nm; 785 nm is recommended as a start).
- Optical power attenuation to avoid photodamage, high‑quality objectives or fibre probes, and effective Rayleigh filters (edge/notch).
- Spectral resolution of at least 2 cm⁻¹ and pixel resolution of ≈ 0.8 cm⁻¹/pixel; recommended spectral range 100–3 500 cm⁻¹ (minimum 500–1 800 cm⁻¹).
- Detectors such as CCD, EM‑CCD or InGaAs arrays with appropriate cooling and low noise.
- Microscope‑based and confocal systems are recommended (Z‑stack, confocal pinhole control, motorised stage) for micro‑layers and multi‑layer analysis.
- Calibration & settings:
- Manufacturer wavelength calibration (using emission lamps) and daily Raman wavenumber calibration using a reference (e.g., silicon ~520.7 cm⁻¹) and recalibration after hardware changes.
- Measurement methods:
- Method 1 - General method for bulk and single-layer plastics.
- Method 2 - Specific test method for multi‑layer film plastics, with layer mapping and thickness probing.
- Analysis & reporting:
- Spectrum matching to reference libraries, interpretation of characteristic peaks (Annex A), spectral database procedures (Annex B), and example measurements (Annexes C–E).
Practical applications and users
ISO 6775:2024 is applicable to:
- Materials and polymers laboratories performing plastic identification and quality control.
- Recycling and circular‑economy operations validating polymer type for sorting and reprocessing.
- Environmental and microplastics researchers identifying polymer particles in samples.
- Product development teams and failure‑analysis labs characterizing unknown polymer components.
- Regulatory bodies, customs and forensic analysts needing consistent, standardised Raman identification.
Benefits include rapid, non‑destructive identification, support for multi‑layer film analysis, and improved comparability of results across labs via standardized calibration and reporting.
Related standards
- ISO 472 - Plastics - Vocabulary (referenced for terms and definitions).
- ISO/IEC Directives (editorial and development context referenced in the foreword).
Annexes in ISO 6775 provide characteristic Raman peaks, database identification guidance, worked examples and multi‑layer measurement examples to support practical implementation.
