Effect of Acid-activated Bentonite on Rheological Properties of Paper Coatings

Effect of acid-activated bentonite on the rheological properties of paper coatings was studied. The results showed that the viscosity of the coatings decreased by adding acid-activated bentonite. At low shear rate,except the coatings containing 40% acid-activated bentonite which showed dilatant flow behavior,the paper coatings exhibited the behavior of pseudoplastic fluid,characterized as shear thinning. The flow properties of paper coatings at high shear rate were pseudoplastic fluid. The results obtained from dynamic viscoelasticity experiment revealed that the dynamic elastic storage modulus and viscid loss modulus of paper coatings decreased with increasing acid bentonite content. Except the coatings containing 40% acid-activated bentonite,the phase angle( δ) at high frequency of paper coatings containing acid-activated bentonite was below 45°. In brief,all of paper coatings belonged to a viscoelastic solid.