The CVST by HITEC Luxembourg is a void-volume
tester, which is derived and further developed
from the ASTM standard D6086 “Standard Test
Method for Carbon Black – Void Volume (VV)” and
compliant to the ASTM standard D7854 “Carbon
Black – Void Volume at Mean Pressure”.
The void volume of a carbon black expressed as a function of
mean pressure is a carbon black structure property. The greater a
carbon black resists compression by having substantial aggregate
irregularity and non-sphericity, the greater the compressed volume
and void volume. Compressing carbon black powder breaks its
agglomerates and aggregates to a similar extent as in the sample
preparation for the compressed oil absorption COAN as per ASTM
D3493. By measuring the decompression of the powder it is
possible to derive a residual void-volume, which reflects well the
COAN – this is naturally intuitive as it describes the powder in a
similar physical condition (i.e. in uncompressed state after breaking
agglomerates/aggregates).
With an exchangeable compression chamber, it is possible to
optimize this new method for best testing conditions. Its control
software, which is under constant evolution, can further determine
other characteristic responses like material friction, work
absorbed by compression/decompression, etc. The CVST by HITEC
Luxembourg complies with the present requirements of standards
on void-volume, but above all it allows to set up test methods and
personalize configurations far beyond the requirements of the
related ASTM method.
The CVST can be used for the characterization of other powder
materials (silica, ceramics, …).