STUDIES OF DILUTE AND CONCENTRATED SOLUTION PROPERTIES OF NATURAL POLYSACCHARIDES

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DILUTE AND CONCENTRATED SOLUTIONS OF POLYSACCHARIDES, SCHIZOPHYLLAN (TRIPLE-STRANDED, NONIONIC) AND XANTHAN (DOUBLE-STRANDED, IONIC), WERE STUDIED BY LIGHT SCATTERING, POLARIMETRY, TITRATION, CALORIMETRY, AND VISCOMETRY, THE MAIN RESULTS AND CONCLUSIONS ARE AS FOLLOWS.1. SCHIZOPHYLLAN IN AQUEOUS SOLUTION UNDERGOES A COOPERATIVE TRANSITION BETWEEN THE ORDERED AND DISORDERED STATES IN THE SIDE CHAIN CONFORMATION, EXHIBITING A PRONOUNCED ISOTOPE EFFECT.2. THE DOUBLE HELIX OF XANTHAN (NA SALT) IN 0.01 M AQUEOUS NAC1 MELTS INTO A DIMERIZED COIL.3. TERNARY SOLUTIONS CONSISTING OF WATER AND TWO SCHIZOPHYLLAN SAMPLES DIFFERENT LARGELY IN MOLECULAR WEIGHT WERE FOUND TO SEPARATE INTO THREE PHASES, TWO CHOLESTERIC PHASES AND ONE ISOTROPIC PHASE.4. AQUEOUS NAC1 SOLUTIONS OF XANTHAN ALSO FORM CHOLESTERIC LIQUID CRYSTALS.5. THE THEORIES FOR ISOTROPIC-LIQUID CRYSTAL PHASE EQUILIBRIUM IN BINARY SEMIFLEXIBLE POLYMER SOLUTIONS ARE COMPARED FAVORABLY WITH DATA FOR VARIOUS POLYMERS INCLUDING SCHIZOPHYLLAN AND XANTHAN.6. THE PHOTON CORRELATION SPECTROMETER CONSTRUCTED IN THIS WORK GAVE ACCURATE DIFFUSION COEFFICIENTS FOR POLYSTYRENE AND ITS LATEX. THE MEASUREMENT ON XANTHAN SOLUTIONS IS NOW IN PROGRESS.7. A MAGNETIC RHEOMETER WAS CONSTRUCTED AND USED TO MEASURE VISCOSITIES OF ISOTROPIC XANTHAN SOLUTIONS AS A FUNCTION OF NAC1 AND POLYMER CONCENTRATIONS. THEY WERE FOUND TO BE ALMOST INDEPENDENT OF NAC1 CONCENTRATION, REFLECTING THE INTRINSICALLY HIGH RIGIDITY OF THE XANTHAN DOUBLE HELIX.