FLORY POLYMER-POLYMER INTERACTION PARAMETER BETWEEN HEMICELLULOSE AND LIGNIN FROM HARDWOOD

The interaction parameter between hemicellulose and lignin from beech wood was ev from vapor pressure osmometric measurements on solvent-polymer and solvent-polymer-polymer solutions. Dimethyl sulfoxide (DMSO) was used as a solvent. The interaction parameters between hemicellulose and DMSO (chi-01) and between lignin and DMSO (chi-02) increase with increasing temperature, and the change with temperature is proportional to inverse temperature. It was found for both polymers that DMSO becomes a "poor solvent" at higher temperature. This result was also derived from the free energy of dilution. The interaction parameter between hemicellulose and lignin (chi-12) was evaluated as a function of temperature from the activity of solvent in a solution of the three components. At 60-degrees-C, chi-12 is positive; it decreases with increasing temperature and becomes negative at 70-80-degrees-C where a minimum is found. Above 80-degrees-C, chi-12 increases again to become positive at 90-degrees-C. Thus, hemicellulose and lignin attract each other at 70-80-degrees-C, but there is repulsion between the polymers at higher and lower temperatures.