Abstract
The intrinsic viscosity at zero rate of shear was determined for several alginate samples ranging in weight-average molecular weight from about 1 × 10 5 to 2.7 × 10 6. The measurements were carried out in aqueous salt solutions of various strengths. The intrinsic viscosity was found to be linear in the reciprocal square root of the ionic strength, and its value at infinite ionic strength could be obtained with good accuracy by extrapolation. An acid-soluble fraction of alginate had the same intrinsic viscosity in hydrogen form at pH 1 as in sodium form at infinite ionic strength. The exponent a in the Mark-Houwink equation decreased with increasing salt concentration, but even at infinite ionic strength the value was very high ( a = 0.84), suggesting that the discharged alginate molecule is very extended in water. Indications for a high degree of extension of uncharged alginate was also obtained from the high value (155 Å) of the Kuhn statistical segment-length at infinite ionic strength. The separation between solvent effects and chain rigidity in causing the extension was found difficult for theoretical reasons, but it is argued that the main cause of the extension is a high degree of chain rigidity. A comparison with results for amylosic and cellulosic chain polymers revealed a close similarity with the latter.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
