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Viscolastic relaxations in solutions of poly(glutamic acid) and gelatin at ultrasonic frequencies
Author(s) -
Wada Yasaku,
Sasabe Hiroyuki,
Tomono Makoto
Publication year - 1967
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1967.360051003
Subject(s) - chemistry , ultrasonic attenuation , attenuation , gelatin , relaxation (psychology) , dissociation (chemistry) , ultrasonic sensor , glutamic acid , thermodynamics , nuclear magnetic resonance , optics , amino acid , organic chemistry , physics , psychology , social psychology , biochemistry , acoustics
Complex shear viscosity η* = η′ – i η″ of poly ( L ‐glutarmic acid) solution was measured by the torsional crystal method at 50 kc./sec. as a function of pH. A sharp peak was found at the midpoint of the helix‐coil transition region in both η′ and η″. The relaxation time is calculated from η′ and η″ assuming a single relaxation process and the peak value at the midpoint of transition is estimated at 10 −6 sec. Such behavior agrees well with the prediction from the theory of Schwarz. The attenuation of longitudinal sound waves at,3 Me./sec. was measured as a function of pH for solutions of poly(glutamic acid), glutamic acid, and gelatin. A small attenuation peak was observed for the three solutions, the peak height being almost, the same for them. The peak is interpreted in terms of the dissociation reaction of side chains.