Barrier and Mechanical Properties of Starch Films Based on Regular Potato Starches and High Amylose Potato Starches

Sammanfattning: The object of this work was to investigate the film properties of modified regular potato starch and modified high amylose potato starch with different small molecules tested as possible plasticizers. The studies focused on barrier properties such as water vapour permeability (WVP, WVPe), the glass transition temperature (Tg) and mechanical (tensile) properties.

The WVP of modified high amylose potato starch was significantly lower than that of the corresponding starches based on regular potato starch, both for free films and for coated filters. The different molecules tested as plasticizers had no significant effect on the WVP. The expected effect of hydrophobization was that the WVP would decrease, but the WVP of the hydrophobized starch was higher than that of the hydroxypropylated starch.

In a special series of mechanical tests, glycerol was used as plasticizer. Small amounts of glycerol did not change the glass transition temperature or the mechanical properties. An amount of of 30 parts per hundred (pph) hade to been added to achieve any effect. With 30 pph of glycerol, both strength and stiffness showed a strong dependence on film thickness.