Starch graft copolymers

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 

Extraction of the PMA homopolymer had little effect on the tensile strength, regardless of the PMA content. The homopolymer content was — 16% of the PMA present. 

Substitution of cornflour for cornstarch yielded more flexible copolymers, with lower tensile strengths but greater elongation and tear strength, compared to starch copolymers.117 Comflour-g-PMA could be extruded into blown films, in contrast with starch-g-PMA prepared from granular starch. The effects of sequential CAN addition were similar to those observed for starch-g-PMA.115 

Henderson and Rudin111 examined the effects of water on starch-PMA and starch-g-PS extrudates of similar add-on. When immersed in water, starch-g-PS gained approximately 9% in weight and 7% in cross-section area, with essentially no water extractables. Starch-g-PMA gained 25% in weight and 50% in cross-section under the same immersion conditions. Extractables for the starch-g-PMA were 12.4%. Water absorption significantly reduced the tensile strengths of the copolymers the 

Starch type Acetone Graft Graft Tensile Elongation, Tear 

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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). 

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. 

Other useful modifications include acetylation, hydroxyethylation, hydro-xypropylation, cationic starches, succinate, and substituted succinate derivatives of starch. In starch-grafted copolymers, free radicals are initiated on the starch that then act as macroinitiators for the acryl or vinyl monomers. These products are used in firefighting fluids, electrolyte solutions for alkaline batteries, wound dressing, and so on. 

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... 

The vast majority of grafting studies have been performed with vinyl monomers. Other types of starch graft copolymers have been prepared from starch and lactones or lactides.2937,2938 Such copolymers could be prepared using reagents in W-dimethylacetamide in the presence of lithium chloride and triethylamine. 

Graft copolymers of starch with acrylonitrile and 2-acrylamido-2-methylpropanesulfonic acid, after saponification, were claimed to be good sorbents.3092 A composite of saponified acrylonitrile-starch-copolymer with vinyl formal polymers showed very good salt-rejection characteristics and served as membranes.3093 The same material prepared with poly(vinyl chloride) has been used in gaskets for concrete pipes.3057 Saponified acrylonitrile-starch graft copolymers blended with C12-C16 alcohols provided excellent water-retention characteristics.3094... 

Acrylic acid or methacrylic acid-starch graft copolymers were proposed as floc-culants for bauxites,2714,3095 agents for sizing cotton,3096-3098 tanning materials,3099 paper additives,3100 and also for sanitary napkins, diapers, tampons, and sick-bed sheets.3101-3104 Particular attention was devoted to the use of vinyl monomer grafted onto crosslinked starch.3105 Other applications include antiflammatory... 

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