Dextrins polymerization

Glucose or maltose by selective fermentation with washed baker s yeast dextrine by difference. b Average degrees of polymerization of dextrine were calculated from their reducing values as follows ... 

The degree of polymerization of the reducing dextrine dropped rapidly to 10 and then slowly to 4. These findings are in accord with the observations of many investigators that the amylase of Aspergillus oryzae causes a very rapid decrease in the viscosities of its substrates and a very rapid disappearance of products which give color with iodine. 

Upon extensive hydrolysis of starch by either of these enzymes, only small differences were observed in the concentrations of the products or in the average degrees of polymerization of the dextrins. These comparisons were made for equivalent stages of hydrolyses and are not necessarily related to the rates of the hydrolysis of starch by these two amylases. 

Average degrees of polymerization calculated from results of acid hydrolysis of dried precipitated dextrins that remained after removal of fermentable sugars. 

According to Flory (10), the concept that proteins and carbohydrates are polymeric goes back to at least the work of Hlasiwetz and Habermann (11). In 1871 they proposed that these substances were made up of a number of species differing from one another with respect to the degree of molecular condensation. Flory also noted that Hlasiwetz and Habermann differentiate "soluble and unorganized" members of these substances, for example dextrin and albumin, from "insoluble organized" members, such as cellulose or keratin. This distinction is the precursor of the present day differentiation between non-crystalline and crystalline polymers. 

Musculus and Meyer (12) measured the diffusion rates of some starches and dextrins in 1881. The work was designed to determine the relationship of these "isomeric or polymeric" forms to the simple sugars from which they were formed. They concluded that dextrin molecules must be much larger than those of the sugars. This work, however, preceeded Raoult s (13) development of the cryoscopic technique for the determination of the molecular weights of dissolved substances, and van t Hoff s (14) formulation of the solution laws. Further, since the vapor density method was obviously inapplicable, it was not possible for them to actually determine the degree of polymerization. 

The reliable generation of deton press under 100 kilobars should offer advantages from an engineering viewpoint in applications where higher pressures are neither needed nor desired. Certain plastic/expl formulations described (Ref 1) offer these advantages in addition to others, such as the capability of being extruded or injection molded into difficult configurations and then polymerized in place. Expls included superfine PETN, acetone fine RDX, dextrinated LA and Thallous Azide... 

Methacrylic esters of poly hydroxy compounds, like glucose (SO, 51, 136), maltose (136), dextrin (136), starch (136), sorbitol (47, 50, 51) and mannitol (47) derivatives, have also been polymerized however the polymers obtained are mostly insoluble and have not been investigated from the point of view of the relationships between optical activity and structure. 

Very early reports on these systems described them as polycondensates, consisting of broad molar-mass distributions with randomly branched topologies. The methods of synthesis included Friedel-Crafts coupling of benzyl alcohols [108] and the polymerization of 2,5,6-tribromophenol involving aryl ether formation [109], In addition, hyperbranched natural carbohydrate polymers, such as amylopectin, dextrin, and glycogen have been extensively studied [73-75]. 

Anionic graft-polymerization of paraformaldehyde onto starch and dextrin has been effected in methyl sulfoxide solution, polymerization being initiated by the carbohydrate potassium alcoholate formed from the reaction of the carbohydrate with naphthalene potassium, a metallation procedure not previously described for carbohydrates.220... 

As I have already indicated, the polymeric carbohydrate materials available from natural sources include gums, starch and dextrins, cellulose, hemicellulose, chitin, and bacterial polysaccharides. 

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