Epichlorohydrin, crosslinked with starch

The treatment of (cyanoethyl)starch with hydroxylamine2478 and its salts gave a cationic amidoxime which was used as a paper strengthener,2479 and it was also useful in the removal of heavy metal cations from wine.2480 An amidoxime was also prepared from epichlorohydrin-crosslinked (cyanoethyl)starch.2481 There are reports on cationic graft polymers, and these are detailed separately in Section XVI, together with other graft polymers. 

Reduction of acetals with NaBH4 was reported,1369 but no applications of the products were given. Crosslinking of starch acetals with epichlorohydrin and similar compounds was also described.1370 A urea-formaldehyde-starch copolymer reacted with hydrogen peroxide and Cu(II) catalysts, thereby producing a starch solution with improved stability of viscosity.1371... 

Borax has frequently been used in conjunction with such reagents as (3-chloro-2-hydroxypropyl)trimethylammonium salts,1853 epichlorohydrin or formaldehyde,1401185318541855 melamine-formaldehyde resins,1856 (carboxymethyl) starch, oxidized (carboxymethyl)starch, (carboxymethyl)starch-acrylamide copolymer,1857 and oxidized starch.1858 Boric acid was also used jointly with formaldehyde,1859 and starch dialdehyde has been crosslinked with boric acid.526... 

Acylated starch can be copolymerized to yield materials for films, lacquers, and fibers.2111 Starch acetate copolymerized with epichlorohydrin was extruded to give cold-water swelling products with a high degree of friability.2112 Epichlorohydrin-crosslinked starch has been acylated with 2,3-di-O-benzoyl-L-threaric anhydride.2113 The reaction proceeded either in /V,/V-dimethy 11 ormam ide or in toluene, and the non-crosslinked product has also been reported.2114... 

Aminated starches have been further converted. For example, dimethyl-aminoethyl starch could be converted into glycosides by alcoholysis,2442 phosphorylated with sodium dihydrogenphosphate, and oxidized with hydrogen peroxide to carboxyl derivatives.520 Additional information on this subject can be found in Section VII. 2-Hydroxypropyltrimethylammonium chloride starch has been crosslinked with epichlorohydrin.2443 In contrast to animation, which requires basic solutions, phosphorylation occurs at pH 6.2444... 

Reaction of starch dialdehyde with urea gave a condensation product.442,2633 Carboxyamides,2624 including acrylamide,524,585 were also allowed to react with starch dialdehyde. Condensation can occur between starch dialdehyde and macromolecules containing amido groups, for instance, epichlorohydrin-crosslinked polyamide resin,598 ammonia-diethylamine-epichlorohydrin copolymer,588 dicyanamide-formaldehyde resins,565,566 quaternary alkylam-monium compounds,596,610,611 amino acids,2634,2635 protein,626,2636-2639 and aminoalkylated starch.2515 The reactions are favored by low pH. The guanidino moieties of proteins entered the condensation the most readily. 

Poly(amino acids)2892 and polypeptides2893 can also be grafted onto starch. Starch was first alkylated in the presence of lithium naphthalene, and then the alkoxy derivatives were reacted with /V-carboxy anhydrides. Poly(amide amines) were produced by reacting amines with dioic acids on starch and then crosslinking with epichlorohydrin or 1,2-dichloroethane 2894 Grafting of starch with a synthetic polymer chain, for instance, polystyryl carboxylate anions prepared by an anionic polymerization, can be carried out on a blend of starch and cellulose functionalized by sulfonation, mesylation, or tosylation. In this manner, cellulose-starch graft copolymers were prepared.2895... 

Sreedhar, B., Chattopadhyay, D.K., Karunakar, M.S.H., and Sastry, A.R.K. 2006. Thermal and surface characterization of plasticized starch polyvinyl alcohol blends crosslinked with epichlorohydrin. J. Appl. Polym. Sci. 101 25-34. 

Fig. 4.38. Corn starch viscosity curves as affected by crosslinking degree. Instruments Brabender amy-lograph a control, b crosslinked with 0.05%, c 0.10%, d 0.15% epichlorohydrin (according to Pigman, 1970)...

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