Particle Size Determination of Nanosized Pigments Using Ultra-Small Angle X-ray Scattering USAXS
Pigments are commonly used in everything from paints, through to inks and dyes. The particle size and distribution of the pigments can determine properties such as appearance, quality, functionality and processability.
Particle Size Measurement
Pigments can have particle sizes in the sub 10nm region. This is the limit of resolution of popular techniques such as laser diffraction. SAXS or Small Angle X-ray Scattering is suitable for measuring particle sizes in the range 1-50nm, and can be extended to 800nm in USAXS (Ultra-Small Angle X-ray Scattering) mode.
SAXS and USAXS
Both SAXS and USAXS are suited to solids (e.g. fillers in rubber) and dispersions with no need for dilution. They are also non-destructive testing procedures that can determine:
- Particle size and distribution
- Particle shape
- Pore size and porosity
- Other advanced property determinations
Ultra-Small Angle X-ray Scattering Analysis of Pigments
In this application note, four coloured ink pigments (black, blue, red and yellow) are examined using USAXS. This investigation was carried out in a Rigaku SmartLab, a high precision multi-functional diffractometer that can be operated in a range of different modes including USAXS and SAXS. The system features the new SmartLab Studio II software with MRSAXS plugin. Rigaku also offer dedicated SAXS instruments.
The results in the application note show the resultant scattering patterns generated by each pigment, with each pattern taking about 20 minutes to generate.