黑料网

Abstract

The rheological properties of starch-polyacrylamide graft copolymers prepared in water and in dimethyl sulfoxide (DMSO) were investigated and compared. Both materials can absorb huge amount of water and form gels. Both water-made and DMSO-made starch-polyacrylamide graft copolymer gels exhibited viscoelastic solid properties. The analysis of modulus, concentration dependence, and stress relaxation measurements indicated that both water- made and DMSO-made starch-polyacrylamide gels were physical gels meaning that the cross-linkers between the molecules were of physical junctions. The linear range rheological property analysis suggested that water-made starch-polyacrylamide graft copolymers should be ‘weak’ gels at lower concentrations (<7%), but be ‘strong’ gels at higher concentrations (≥ 9%) however, the DMSO-made starch-polyacrylamide graft copolymers should be ‘weak’ gels at all measured concentrations. The non-linear steady shearing rheological properties studies showed that both water- made and DMSO-made starch-polyacrylamide graft copolymer gels exhibited shear thinning behaviour, which can be well fitted with the power law constitutive equation. The function and behaviour of both water-made and DMSO-made starch-polyacrylamide graft copolymer gels imply that these starch-based biomaterials can be potential candidates for applications in cosmetic and wound skin care gels; and the desired material’s behaviour and property can be manipulated by the copolymer’s concentration and preparation method such as in water or in DMSO.

Keywords: Biodegradable material; Graft copolymer; Polyacrylamide; Rheology; Starch; Viscoelastic properties