Swelling and rheology of saponified starch-g-polyacrylonitrile copolymers. Effect of starch granule pretreatment and grafted chain length
1978
Taylor, N.W. | Fanta, G.F. | Doane, W.M. | Russell, C.R.
In the reported experiments, a series of well-characterized starch-g-polyacrylonitrile (PAN) graft copolymers was prepared from corn starch which had been heated in water at temperatures up to 94 degree C to vary the extent of starch granule swelling and disruption. Graft polymerization onto gelatinized starch gave less frequent grafting of higher molecular weight PAN than comparable graft polymerizations onto ungelatinized starch. A graft copolymer was also prepared from gelatinized starch under high dilution conditions to give lower molecular weight grafted PAN and more frequent grafting. Graft copolymers were then saponified with sodium hydroxide to convert nitrile substituents to a mixture of carboxamide and sodium carboxylate. With the exception of the graft copolymer prepared under high dilution conditions, the physical properties of saponified graft copolymers depended on whether or not the granules of starch were gelatinized before graft polymerization. The saponified graft copolymer prepared from gelatinized starch under high dilution conditions more closely resembled those prepared from ungelatinized starch, suggesting that molecular weight of grafted PAN and the grafting frequency rather than starch granule pretreatment might be the most important factor which influences properties.
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