Does the same absorbance peak guarantee equal weatherability?
A raw material spectrum does not establish distribution, migration or retention of an additive in a film or thick part.
Include an absorber-free control at the target resin and thickness
Prepare equal-thickness parts in the intended resin, including an untreated control. Compare appearance before and after processing and properties after exposure. Record surface bloom separately from weathering performance.
How can a combination with HALS be justified?
Test the absorber alone, HALS alone and the combination in the same resin against the target endpoint. Polyolefin weatherability: At equal wall thickness, compare color difference, transmittance and mechanical properties before and after aging. Colored or transparent parts: Check initial color and transmittance, then inspect for surface blooming.
Checking UV-531 assay and Absorption spectrum
UV-531 assay (% by mass): Agree the requirement for the identified substance and specified chromatographic method. Absorption spectrum (Wavelength (nm) and absorbance): State solvent, concentration and optical path length. Volatility or migration (Specified method): Define the use temperature, contact medium and test duration.
What to record
- Resin
- Specimen thickness
- UV-531 dose
- Exposure conditions
- Precipitation or bloom
- Property retention
Technical references
Products and processes
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