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Surface Energy of Extruded and Jet Cooked Starch
Author(s) -
Lawton J. W.
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.19950470206
Subject(s) - starch , contact angle , surface energy , materials science , polar , surface roughness , amylose , maize starch , composite material , chemistry , physics , organic chemistry , astronomy
Contact angles of water and other liquids were measured on films and extruded ribbons of normal, high amylose and waxy cornstarch using a Chan dynamic contact angle analyzer. The contact angles were then used to calculate the critical surface energy of the starch via a Zisman plot. Attempts were also made to use the contact angles to calculate the surface energy of starch via the harmonic‐mean method. No differences were found for the critical surface energy due to starch type. Using a composite of all contact angles for the three different starches, an average critical surface energy of 40 dynes/cm was calculated. This value was close to the literature value of 39 dynes/cm found for starch. The surface energy of starch, calculated from the harmonic‐mean method, was more variable and ranged from 35‐42 dynes/cm. The harmonic‐mean method not only calculates the surface energy, but it also estimates the polar and non‐polar components of surface energy. The estimate calculated for the polar portion for the surface energy of starch was too low for a polar solid like starch. Values for the polar component range from 0.3 to 10 dynes/cm. A theoretical argument is made for the surface energy of starch being greater than the 39 dynes/cm now reported in the literature.