Graft polymers of eucalyptus lignosulfonate calcium with acrylic acid: synthesis and characterization.

The graft copolymerization of eucalyptus lignosulfonate calcium (HLS-Ca) from hardwood and acrylic acid (AA) was investigated by using Fenton agent as a coinitiator. The influences of reaction conditions on grafting parameters i.e. product yield (Y%), AA conversion (C%), grafting ratio (G%) and grafting efficiency (GE%) were carefully studied. The effects of the phenolic hydroxyl (Ph-OH) group on the polymerization of AA and grafting reaction were researched. Graft copolymers were identified by the new absorption at 1,727 cm(-1), more homogenized morphology and higher decomposition temperature after grafted with AA, as illustrated in FTIR, SEM and TG spectra. The optimum synthesis conditions are as follows: H2O2=25.2 mol/L, FeCl2=63.0 mol/L, T=50°C and t=2h and the optimum percentages of Y, C, G and GE are 97.61%, 95.23%, 71.29% and 78.85%, respectively. The Ph-OH group of HLS-Ca cannot inhibit the polymerization of AA and is involved in the grafting reaction as an active center.