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Ultrasonic Investigation of the Gelation Process of Poly(Acrylamide) Gels
Author(s) -
Norisuye Tomohisa,
Strybulevych Anatoliy,
Scanlon Martin,
Page John
Publication year - 2006
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200651029
Subject(s) - materials science , ultrasonic sensor , polyacrylamide , phase (matter) , acrylamide , attenuation , exothermic reaction , self healing hydrogels , elastic modulus , analytical chemistry (journal) , composite material , polymer chemistry , chemistry , optics , chromatography , polymer , monomer , organic chemistry , acoustics , physics
The time evolution of ultrasonic velocity and attenuation has been investigated in‐situ during the gelation process of polyacrylamide (PAAm) hydrogels. Longitudinal ultrasonic pulses were transmitted through the gel samples and continuously recorded to obtain the magnitude and phase of the waves as a function of time and frequency, enabling the attenuation coefficient, α , and phase velocity, v p , of PAAm gels to be determined. The reaction was characterized by (1) an initial rapid increase in α and v p , and (2) a subsequent reduction after both quantities passed through a peak associated with the exothermic reaction for the PAAm gelation. The square of v p is proportional to the longitudinal modulus of the sample and inversely proportional to the density, and the values of v p for the aged gels were smaller than those before the gelation. The cross‐linker concentration dependence was further examined in order to investigate the gelation process accompanied by phase separation.