The talc mineral samples and the hyperdispersant were analyzed using a Spectrum One (Perkin-Elmer) FTIR spectrometer working in transmission mode with a resolution of 2 cm−1. The talc mineral samples were mixed with KBr in a pellet for the FTIR spectrum recording; no band was observed at 1424 cm−1 indicating the absence of calcium carbonate in talc mineral samples. A film of the liquid hyperdispersant was deposited on a KBr window for the FTIR spectrum recording. The two characteristic bands of a secondary amine were observed for the hyperdispersant spectrum: one at 3300 cm−1 (corresponding to the N–H stretch) and the other at 1500 cm−1 (corresponding to the N–H bend).
The specific surface area (SBET) of talc mineral samples was determined by the BET technique using nitrogen adsorption on a Nova 3200 (Quantachrome). The samples were degassed at 150 °C for 12 h prior to analysis.
The particle size distribution and the volume-surface average diameter (d32) of dry talc samples were determined using a Mastersizer 2000 (Malvern) with a Scirocco sample handling unit.
The X-ray diffraction patterns for the talc mineral samples were obtained on a Miniflex (Rigaku) diffractometer (40 kV/30 mA) in the range 2θ = 3–60° employing Cu Kα radiation with a wavelength of 1.54 Å. The characteristic peaks of calcium carbonate were not observed, confirming the absence of this compound in the studied samples.
The oil absorption of talc mineral samples was measured following ASTM method D 281.
The contact angle measurements were carried out using a tensiometer K12 (Krüss) and the Krüss powder sample holder. The geometric factor c of talc mineral samples was determined through the capillary rise wetting of n-hexane (γL = 18.4 mN m−1), recording the increase in weight versus time. The same procedure was carried out with diiodomethane, ethylene glycol, and water versus each talc mineral sample to determine their contact angle. The measurements were repeated three times and average results are reported in Table 3. The experimental temperature was held at 25 °C