Synthesis of resorcinol-formaldehyde resin and its gellation performance with HPAM

The crosslinker for gellation of partly hydrolyzed polyacrylamide was synthesized by the reactants of resorcinal and formaldehyde in ethanol, with alkali as catalysts. The effects of solvent, molar ratio, reaction temperature and formation temperature on gellation were studied. The results showed that: ①the time span for effective crosslinking of HPAM was prolonged profoundly when the organic solvents with dielectric constant smaller than that of water were adopted as reaction media; ②the HPAM gel with optimum viscosity and strength was obtained when the crosslinker was synthesized from resorcinal and formaldehyde in the molar ratio of 1.0 : 2.0; ③the reaction temperature of 40 ℃ was conducive to the hydroxymethylation of resorcinal and formation of A-stage resin, by which more active sites were available for crosslinking with HPAM; ④the gel formed from HPAM and resorcinal-formaldehyde resin can be applied for the formation with temperature in the range of 50 ℃ to 90 ℃.