Overview
ISO 21475:2019 specifies laboratory methods to determine the wavelength-dependent degradation of plastics using spectrally dispersed ultraviolet (UV) and visible radiation. The standard defines how to expose specimens (films, liquids, plaques, pellets, powders, sheets, discs) to a spectrally dispersed beam, measure the resulting changes in optical or mechanical properties, and derive the material’s action spectrum (spectral sensitivity) across roughly 200–700 nm.
Keywords: ISO 21475:2019, plastics testing, spectrally dispersed radiation, wavelength dependent degradation, spectral response, UV-visible.
Key topics
- Principle: Expose a specimen to spatially separated wavelengths so that position on the specimen corresponds to wavelength; quantify degradation as a function of wavelength.
- Exposure device: Use a broadband source (typically a Xenon arc lamp), entrance slit, diffraction grating (blazed where appropriate), and optics to form a dispersed image at the specimen plane. Remove ozone if generated.
- Spectral characterization: Measure spectral irradiance Eλ (W·m−2·nm−1) and spectral radiant exposure (J·m−2·nm−1) across specimen positions. Report peak wavelengths λ(x) and irradiance integrals E(x).
- Resolution parameters: Entrance-slit width controls spectral resolution vs irradiance; reciprocal linear dispersion (nm/mm) and spatial resolution (slit image width) are key characterization metrics.
- Instrumentation: Use a calibrated spectroradiometer with a diffusing detector sized to the system spatial resolution. Use appropriate measuring devices for property change with lateral resolution matched to exposure resolution.
- Specimen preparation & conditioning: Prepare and condition specimens per agreement and typically in line with ISO 291; report methods used. Color and optical measurements should be done immediately after exposure or after agreed conditioning.
- Temperature control: Typically ambient; specimen heating by dispersed radiation is negligible but temperature control may be applied and must be reported.
- Reporting: Include apparatus parameters, spectral irradiance maps, specimen conditioning, exposure duration, and measured property changes.
Applications
- Determining spectral sensitivity of polymer degradation and discoloration
- Comparative material screening for UV/visible stability
- R&D for UV stabilizers, additives, and coatings
- Quality assurance and accelerated degradation studies for outdoor/indoor exposure simulations
Who uses it: materials scientists, polymer formulators, testing laboratories, product designers, failure analysts, and regulatory bodies concerned with polymer weathering.
Related standards
- ISO 291 - Standard atmospheres for conditioning and testing
- ISO 472 - Plastics - Vocabulary
- ISO 4582 - Determination of changes in colour after exposure to solar or laboratory radiation
This standard helps organizations generate quantitative, wavelength-resolved degradation data for plastics, enabling targeted formulation improvements and more predictive lifetime assessments.