Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 22, 2001
Publication Date: N/A
Interpretive Summary: When plastic films are immersed in hot, diluted solutions of starch pre- pared by steam jet cooking, a thin layer of starch is deposited on film surfaces as the starch solutions are allowed to cool. Although the amount of deposited starch is so small that it is barely visible, these coatings greatly enhance the compatibility of the films with aqueous systems. Starch coatings are composed of complexes that are formed from the amylose component of starch and the small amount of native lipid material normally present in cereal starch granules. Although starch can be removed by gently rubbing water-wet film surfaces, air dried coatings are firmly attached and do not easily separate from the surface. Water- compatible coatings on plastic film surfaces helps to reduce static build up, alters friction and adhesion properties, improves absorption of dyes and inks, and enhances compatibility of the film with body fluids.
Technical Abstract: Thin starch coatings were deposited onto polyethylene (PE) film surfaces when PE films were immersed in 1 percent jet cooked starch solutions and the hot solutions were allowed to cool. Normal cornstarch, waxy corn- starch, high amylose cornstarch and defatted normal cornstarch were used in these experiments. Amounts of adsorbed starch varied from about 0.03-0.05 mg per cm of PE, and these starch coatings imparted hydrophilic properties to film surfaces. Although starch could be removed by gently rubbing water-wet PE surfaces, air dried coatings were more firmly attached and did not separate from the PE surface when films were bent or flexed. Microscopy of starch-coated film surfaces showed that starch was deposited as particles less than 1 micro in diameter and also as aggregates of these sub-micron particles. Surface-deposited starch in all experiments contained 90-100 percent amylose, and X-ray diffraction patterns were indicative of helical inclusion complex formation with native lipid.