The influence of maltodextrins on the structure and properties of compression-molded starch plastic sheets

✍ Scribed by Jeroen J. G. van Soest; Pieter M. Kortleve

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 212 KB
• Volume: 74
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19991128)74:9<2207::aid-app10>3.0.co;2-3

✦ Synopsis

Starch plastic sheets were prepared by compression molding of starchbased plastic granulates. The granulates were prepared by extrusion processing of mixtures of granular potato starch and several maltodextrins (5% w/w) in the presence of glycerol and water as plasticizers and lecithin as melt flow accelerator. The materials were semicrystalline, containing B-type, V h -type, and E h -type crystallinity. The properties were dependent on water content. For the materials, a brittle-to-ductile transition occurred at a water content in the range of 11-12%, which was in accordance with the observed glass transition temperature. The structural and mechanical properties were a function of starch composition and maltodextrin source as well as molding temperature. The amount of granular remnants and residual B-type crystallinity decreased with increasing processing temperature. The amount of recrystallized singlehelical amylose increased with increasing temperature. At molding temperatures in the range of 180 -200°C, a sharp decrease in starch molecular mass occurred. The influence of molding temperature was reflected in a sharp increase in elongation at molding temperature above 160°C and a gradual decrease in elastic modulus. The tensile strength showed an initial small increase up to 160°C and a sharp decrease at higher molding temperatures.