Glass transition temperature of thermoplastic starches

International Agrophysics (Impact Factor: 1.12). 01/2005; 19(3).
Source: DOAJ


Thermoplastic starch was produced by mixing potato starch and glycerol in a single screw extruder. The glass transition temperatures of the materials obtained were measured by differential scanning calorimetry (DSC). Both the influence of extruder parameters and material parameters, such as moisture and glycerol content and amyloses/amylopectine ratio were investigated. Repeated extrusion cycles affect the glass transition temperature only to a very small extent.

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    • "Moreover, a decrease in the Tg has been associated with the greater mobility of the starch chains, caused by the greater interaction between the hydroxyl groups of the starch chains and the molecules of the plasticizer (glycerol) (Mali, Grossmann, García, Martino, & Zaritzky, 2006). Additionally, lower enthalpy values (DH) associated to the glass transition have been related to the weakening of the inter and intramolecular interactions between starchestarch chains (García et al., 2000a, b; Mali et al., 2002; Mitrus, 2005; Pelissari et al., 2013). According to Bair (1981), García et al. (2000b), and Bertuzzi, Vidaurre, Armada, and Gottifredi (2007), this leads to a decrease in growth of the crystal phase in these semi-crystalline biomaterials, since this impedes the alignment and recrystallization of starch molecules. "
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    ABSTRACT: Environmental problems with conventional packaging materials developed the need of searching for new alternatives. Thermoplastic starch polymer (TPS) has been found to be a good source of raw materials for new packaging materials. In the paper changes of microstructure of TPS produced from different type of starch with glycerol content have been discussed. In general it can be stated that an increase of glycerol content in the mixture improves material structure quality.
    International Agrophysics 01/2006; 20(1). · 1.12 Impact Factor

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