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

In this study, the swelling 'behavior of a konjac glucomannan (KG)fn-carrageenan (CA) mixed gel was investigated far examining its possibility as a new type of material for an actuator. Volume changes of a KG/CA mixed gel have 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 prepared by! adding 0.3 wt% of Ca(OH)(2), and immersed in distilled-water containing different concentrations of acetone (0 similar to 50 vol%) at 20 similar to 60 degrees C. The changes in volume for different values of pH 0 similar to 13 were also examined in NaOH and HCl aqueous solutions. In aqueous acetone at a concentration below 20 vol%, the specimens were swollen in a short time at an temperatures. In the solutions containing acetone above 40 vol%, the specimens always shrank, At 50 degrees C the equilibrium swelling 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 about 5 and 10. It may be concluded that the KG/CA. mixed gel is an amphoteric gel which can strongly respond to both acidic and basic functional groups of environment.