Vinyl acetate-starch graft copolymers

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). 

Graft copolymers of starch and vinyl acetate (VA) have been prepared using Co60 irradiation.110 Near-quantitative conversions of monomer to polymer were reported when the radiation dose was l.OMrad, although the grafting efficiency was <50%. Lower radiation doses gave lower conversions and add-ons. When 10% methacrylate was added to the monomer mixture, grafting efficiency was improved to 70%. Selected copolymers were treated with methanolic sodium hydroxide to yield starch-poly(vinyl... 

Hydrolysis of starch graft polymers formed with vinyl acetate was reported to produce polyfvinyl alcohol)-grafted starches using oxidized starches.3021-3027 Hydrolysis of graft copolymer with 72% aqueous sulfuric acid and determination of glucose in the hydrolyzate by the Fehling reagent can be used.3028... 

There have been many studies of graft copolymer formation initiated by ionizing radiation, and methods have been discussed.88 Among the systems studied are styrene onto polyethylene,88 styrene onto polypropylene,100 styrene onto Nylon-6,101 styrene onto ethylene-vinyl acetate copolymers,102 styrene and MMA onto natural rubber,103 pentafluorostyrene onto Nylon and polyethylene,104 acrylamide onto Nylon-6,105 acrylamide onto starch,100 vinyl monomers... 

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