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The Influence of Acid Hydrolysis of Potato Starch on the Stress‐Strain Propoerties of Thermoplastic Starch
Author(s) -
van Soest J. J. G.,
Benes K.,
De Wit D.
Publication year - 1995
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19950471106
Subject(s) - amylopectin , starch , amylose , thermoplastic , hydrolysis , acid hydrolysis , molecular mass , materials science , polymer , chemistry , ultimate tensile strength , extrusion , polymer chemistry , chemical engineering , composite material , food science , organic chemistry , enzyme , engineering
Potato starch has been hydrolysed lowering the molecular mass. The influence of starch molecules mass on the mechanical properties of thermoplastic starch has been investigated. Acid hydrolysis was performed with hydrochloric acid in various concentrations and time spans. Acid hydrolysis of the granular potato starch decreased both the molecular mass of amylose and amylopectin. The thermoplastic materials have been made by extrusion processing of the various starches with fixed amounts of water and glycerol. The stress‐strain properties showed to be influenced by molecular mass. The materials were rubbery at 20°C and 60% relative humidity. Although the tensile stress did not change significantly, the elastic modulus increased with an decrease in molecular mass. This increase was explained by differences in starch structure and morphology. The higher of the low molecular mass materials could result in a more rapid starch structural ordering. The elongation and tearing energy increased with incrasing molecular mass. Theses effects were explained by the higher amylose chain length and amylopectin endgroups chain length resulting in a more entangled polymer matrix.