Starch grafts

Although they lack commercial importance, many other poly(vinyl acetal)s have been synthesized. These include acetals made from vinyl acetate copolymerized with ethylene (43—46), propjiene (47), isobutjiene (47), acrylonitrile (48), acrolein (49), acrylates (50,47), aHyl ether (51), divinyl ether (52), maleates (53,54), vinyl chloride (55), diaHyl phthalate (56), and starch (graft copolymer) (47). 

This is a highly selective process and very good results on cellulose and starch grafting have been observed. Ceric ion initiated grafting is usually carried out at lower temperatures and, therefore, wastage of monomer in chain transfer reactions is minimal. 

Dragunski, D. C. and PawHcka A. (2001). Preparation and characterization of starch Grafted with Toluene Poly (propylene oxide) diisocyanate. Mater. Res., 4, 77-81. 

Results and Discussion. Of the 12 samples of starch graft copolymer synthesized, half were hydrolyzed to anionic polyelectrolytes. Synthesis data on these 6 samples are given in Table 2. These particular samples were chosen for hydrolysis because the samples can be intercompared to see the effect of synthesis variables on ultimate product properties. Samples 5, 8, and 11 have the same mole ratio of cerium ion to starch backbone, N, in their reaction mixture. Samples 7, 8, and 9 all have the same refctable mass per starch molecule,... 

Starch ethers, 4 720 Starch graft copolymers, 4 722 Starch-granule morphology, 26 273 Starch hydrolysates, hydrogenated, 12 39 Starch industry, enzyme use in, 10 252-253... 

Ce Ion Initiation. Initiation of grafting with Ce ions was introduced by Mino et al. 7. The process has been widely studied and even applied to industrial production of cellulose and starch graft copolymers. A mechanism is derived from model experiments with low molecular weight vicinal diols in acid aqueous solution. The first step (22) is OH OH... 

Ihe reaction of starch with oeric salts leads to formation of macroradicals vhich can initiate the polymerization of a wide variety of monomers to yield starch graft copolymers. Graft oopolymers of acrylonitrile and starch are easily prepared Icy technique (Equation 1), and se xxiif ication of starch-g-ipolyacry-lonitrile (Equation 2) yields absorbent polymers that can take jp... 

Zhang, L. M., Hu, Z. H. (2002). Synthesis and thermal degradation of a novel starch graft copolymer incorporating a sulpfobetaine zwitterionic monomer. Starch, 54, 290-295. 

Superabsorbent polymers are now commonly made from the polymerization of acrylic acid blended with sodium hydroxide in the presence of an initiator to form a polyacrylic acid, sodium salt (sometimes referred to as cross-linked sodium polyacrylate). Some of the polymers include polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxy-methyl-cellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile to name a few. The latter is one of the oldest SAP forms created. 

The second soluble starch-g-PAN (No. 3) was prepared by subjecting another starch graft copolymer to a mild acid hydrolysis to partially depolymerize the starch moiety. The ethanol-water solvent system apparently promotes a greater number of starch PAN crosslinks than water, as evidenced by the lower solubilities (45 vs. 71% and 42 vs. 65%) and the higher viscosities for water dispersions (2400 vs. 920 cp and 690 vs. 

Starch grafts are a new class of products for use on the size press.212,213 They have high water retention and form flexible films. They are offered as a liquid, ready-to-use binder on conventional and metered size presses and on calender water boxes. Starch grafts are used in pigmented formulations for the production of film-coated offset, recycled offset, textbook and LWC (lightweight coated) grades, and as precoat for double-coated, sheet-fed offset grades. 

An early application of starch graft copolymers claims that incorporation of graft copolymers of starch or other polyols with ethyl or butyl acrylate into polystyrene improves the impact resistance if the polyol content is less than 20% of the graft.102... 

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