End Group Structure of Polyvinyl Alcohol¹

Abstract

compose amylose, and the value obtained for iodine absorption may be only a practical maximum and fortuitous. Packing considerations alone would allow about one iodine molecule for five glucose residues, since one molecule would require about 6.8 A. along the helix. Furthermore, it is hard to understand why reflections of the type (00hi) are absent if the iodine molecules are spaced 7.91 A. apart along the helix. It seems possible that their arrangement is at random in a set of six equivalent positions per turn in the helix, giving rise to an effective sixthing of the spacing along the c axis. Unfortunately, the temperature factor for the complex is so high that the reflection (006) could not possibly be observed at room temperature. This leaves the space group in doubt. Summary 1.The amylose -iodine complex has a hexag-onal unit cell, 0 -12.97, Co = 7.91, dm = 11.23 A.2. The unit cell confirms a helical structure for the starch-iodine complex; 12.97 A. is the diameter of the helix, 7.91 Á. is the length of a turn in the helix. These dimensions are in good agreement with the dimensions of a space-filling model of a helix with six glucose residues per turn.

Stimulation of the Growth of a Strain of Corynebacterium Diphtheriae by Polyvinyl Alcohol

“…The chemistry of polyvinyl alcohol indicates a linear structure with terminal aldehyde groups (Marvel and Denoon, 1938;Marvel and Inskeep, 1943):…”

Oxidative Degradation of Polymers. III.

“…It is also expected that photo chemical cleavage of ketone will reduce the molecular weight. Another product of interest is acetaldehyde, formed by the reverse aldol-type reaction, (19,20) where β-hydroxyaldehyde or ketone is cleaved in alka line aqueous solution.…”