Effects of solvent, pH and temperature on volume changes of a konjac glucomannan/kappa-carrageenan mixed gel

In this study, the swelling 'behavior of a konjac glucomannan (KG)fn-carrag eenan (CA) mixed gel was investigated far examining its possibility as a ne w type of material for an actuator. Volume changes of a KG/CA mixed gel hav e been studied with reference to the effects or solvent, pH and temperature . The rectangular specimen (10x30x3 mm(3)) containing 2.0 wt% KG/CA was pre pared by! adding 0.3 wt% of Ca(OH)(2), and immersed in distilled-water cont aining different concentrations of acetone (0 similar to 50 vol%) at 20 sim ilar to 60 degrees C. The changes in volume for different values of pH 0 si milar to 13 were also examined in NaOH and HCl aqueous solutions. In aqueou s acetone at a concentration below 20 vol%, the specimens were swollen in a short time at an temperatures. In the solutions containing acetone above 4 0 vol%, the specimens always shrank, At 50 degrees C the equilibrium swelli ng ratios were generally lower than those at 40 degrees C. Effect of pH was then examined, and high swelling in aqueous solutions was observed at pH a bout 5 and 10. It may be concluded that the KG/CA. mixed gel is an amphoter ic gel which can strongly respond to both acidic and basic functional group s of environment.