Submitted to: Biomacromolecules
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/6/2003
Publication Date: 12/9/2003
Citation: Liang, C., Gordon, S.H., Imam, S.H. 2003. Starch graft poly(methyl acrylate) loose-fill foam: preperation, properties and degradation. American Chemical Society. Biomacromolecules, 5(1):238-244. Interpretive Summary: An improved chemical grafting procedure was developed to obtain starch-based loose-fill foam by single screw and twin screw extrusion. The loose-fill foam had compressive strength and resiliency comparable to expanded polystyrene foam, but higher bulk density. The foam also had better moisture and water resistance than other competitive starch-based. Biodegradation tests indicated that foam biodegraded rapidly under natural environmental conditions.
Technical Abstract: Starch graft poly(methyl acrylate) (S-g-PMA) was prepared by ceric ion initiation of methyl acrylate in an aqueous corn starch slurry (prime starch) which maximized the accessibility of the starch for graft polymerization. A new ceric ion reaction sequence was established as starch-initiator-methyl acrylate followed by addition of a small amount of ceric ion solution when the graft polymerization was almost complete to quench the reaction. As a result of this improved procedure, no unreacted methyl acrylate monomer remained, and thus essentially no ungrafted poly(methyl acrylate) homopolymer was formed in the final grafted product. Quantities of the high purity S-g-PMA so prepared in pilot scale were converted to resin pellets and loose-fill foam by single screw and twin screw extrusion. The use of prime starch significantly improved the physical properties of the final loose fill foam, in comparison to foam produced from regular dry corn starch. The S-g-PMA loose-fill foam had compressive strength and resiliency comparable to expanded polystyrene, but higher bulk density. The S-g-PMA loose-fill foam also had better moisture and water resistance than other competitive starch-based materials. Studies indicated that the starch portion in S-g-PMA loose-fill foam biodegraded rapidly while poly(methyl acrylate) remained relatively stable under natural environmental conditions.