Effect of both grafting and blending modifications on the performance of lignosulphonate-modified sulphanilic acid–phenol–formaldehyde condensates

Modifying sulphanilic acid–phenol–formaldehyde condensates (SPF) with sodium lignosulphonate (LS) allows for both the grafting (GSPF) and blending (BSPF) of a series of products from SPF and LS with different LS content. The grafted macromolecule SPF-g-LS was confirmed to exist in GSPF by low-angle laser light scattering (LALLS) and Fourier-Transform infrared (FTIR) spectroscopy. GSPF formed different adsorption configurations on cement particles than BSPF, which ultimately affected their dispersive properties, because of the high charge density and large steric hindrance of the SPF-g-LS macromolecule. Both the absolute value of the ζ potential and the paste fluidity of the cement particles were greater for GSPF than BSPF at identical LS contents. GSPF and BSPF both significantly inhibited cement bleeding relative to SPF; however, this inhibition was greater for GSPF than BSPF at identical LS contents.