SMALL-ANGLE X-RAY-SCATTERING OF HYDROPHILIC AND HYDROPHOBIC SIO2 PARTICLES

Small angle X-ray scattering of hydrophilic (Aerosil 200) and hydropho bic (Aerosil R972) SiO2 particles was studied by a compact Kratky came ra in He atmosphere. The scattering intensity functions of the hydroph ilic and hydrophobic colloid particles are not very different; however , the primary intensity I-0 is considerably larger for hydrophobic par ticles. The effect of hydrophobization is well demonstrated by the rep resentation of the experimental data according to the Debye-Bueche fun ction. From this function the correlation length l(c), the tail end co nstant K-p the invariant M-1, and the specific surface area of the pow der can be calculated. The scattering functions also yield the surface fractal dimension of the silica particles. (C) 1997 Elsevier Science B.V.