Pasting, swelling and solubility properties of UV initiated starch-graft-poly(AA)

UV-initiated graft copolymerization of sago starch with acrylic acid (AA) at low level (2.5%, 5%, 7.5% and 10% w/w) was investigated. The UV curing technique and procedure was found to successfully produce starch-graft-poly(acrylic acid) [S-g-poly(AA)]. The carboxyl group content was found to increase with increasing % of monomer. Rapid visco-analyzer (RVA) pasting profile, swelling and solubility of the samples were studied. UV irradiation of sago starch (control) results in high pasting temperature, high peak viscosity and high setback, besides retarding swelling and solubility as compared to the native untreated starch (p<0.05). Pasting temperature was decreased after grafting as compared to the control. S-g-poly(AA) showed higher peak viscosity, peak time and setback than native untreated starch (p<0.05). Breakdown was retarded at 2.5% S-g-poly(AA) but increased at 10%. S-g-poly(AA) exhibited lower swelling power and solubility than the native sample (p<0.05).