Direct Resinification of Konjac Glucomannan via Hot-Press Compression Molding.

Hot-press compression molding was used to resinify a renewable source-derived linear 1,4-linked β-D-glucan copolymer, i.e., konjac glucomannan (KGM), via the generation of reactive aldehyde groups that tend to crosslink with hydroxyl groups of the glucans. The optimal molding temperature was found to be around 170 °C, with keeping the pressure at 20 MPa for 3.5 min and controlling the water content of the starting KGM powder to be around 22%. The molded KGM resin sheets were found to be crystallized in the annealed KGM polymorph form. Dynamic mechanical analysis revealed that the softening initiation temperature of the KGM resin was ca. 100 °C due to an onset of an increase in the loss modulus, E". The representative KGM resin sheets obtained under the optimal molding conditions were transparent, colored brown, and exhibited a tensile strength of 20.8 ± 4.5 MPa, Young's modulus of 2.2 ± 0.3 GPa and elongation at break of 1.1 ± 0.2%. [ABSTRACT FROM AUTHOR]