ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Five different glucomannan samples were recrystallized from dilute solution. Depending on the experimental conditions, the crystals obtained could be identified as corresponding to the mannan I (anhydrous precipitate of more or less regular lozenge-shaped crystals) or mannan II (hydrated gel-forming pseudo-fibrillar precipitate). High-molecular-weight material, low temperature of crystallization, or a polar crystallization medium favored the mannan II polymorph, whereas a low-molecular weight, a high temperature of crystallization, and a crystallization medium of low polarity yielded the mannan I polymorph. Since the base-plane unit-cell dimensions are fairly constant with respect to variation of glucose, it is likely that isomorphous replacement of mannose by glucose occurs in glucomannan crystallization; the data also indicate that perfection of the glucomannan crystals was reduced in specimens having a high glucose:mannose ratio. The oriented crystallization of glucomannan on cellulose microfibrils was also studied under conditions where the mannan I polymorph was obtained. This gave shish-kebab structures that were characterized.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360210206
