Different methods for surface modification of hydrophilic particulates with polymers

Three different methods of attaching polymers to sand are compared: in situ graft polymerization, chemical grafting of preformed polymers, and admicellar polymerization which uses a surfactant template. Sample characterization includes Raman spectroscopy, gravimetric analysis, contact angle measurements, and high solids rheology tests. In all cases, the presence of polymer on the surface was confirmed, but differences in terms of amount of polymer adsorbed, surface chemistry, and interparticle friction were found. The effect of polymer molecular weight for the chemically grafted material was studied as well. An optimum molecular weight around 600,000 g/mol was found for maximum friction reduction in preformed poly(vinylpyrrolidone)-modified sand samples.