binding agents, such as UltraBind® (SPEX 3644, USA) and polyvinyl alcohol
(Carlo Erba, Italy), were also tested. For the sake of information,
all binding agents were evaluated in the range from 10 to 50% mm−1
,
with homogenization times from 10 to 30 min.
Pellets (test samples) were prepared in a Spex model 3624B X-Press
by transferring 0.5 g of powdered material to a 15 mm die set and
applying 8.0 t cm−2 for 5 min. The pellets were kept in a desiccator
before analysis.