BULLETIN of the

POLISH ACADEMY of SCIENCES

TECHNICAL SCIENCES

 BULLETIN of the POLISH ACADEMY of SCIENCES: TECHNICAL SCIENCES
Volume 55, Issue 2, June 2007

Micro and Nano-scale mechanics
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pp 239 - 244

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Effect of high hydrostatic pressure on structure of gelatin gels

L. KULISIEWICZ, A. BAARS and A. DELGADO
The present contribution reports on the rheological investigations concerning influence of high hydrostatic pressure on the molecular structure of gelatin gels. For the purpose of the study, a torsional shear wave rheometer for in-situ investigations of viscoelastic substances under high pressure was developed. Small amplitude vibrations generated by piezoelectric elements are used to determine the storage modulus of the investigated medium. The system is able to stand pressures up to 300 MPa. The experiments have been carried out with household gelatin (0.1 w/w aqueous solution). The gelification curves revealed similar time course. However, the values of G0 obtained for the gels curing 300 minutes under 100 MPa and 200 MPa were observed to be respectively 2.1 and 4 times higher than at ambient conditions. The increased number of triple helix junction zones is hypothesised to be the cause of this phenomenon as a result of reinforcement of the hydrogen bonds due to pressure. An attempt to cognize the characteristic dimensions of the molecular structure based on the theory of rubber elasticity is made.
Key words:

high hydrostatic pressure, in-situ measurement techniques, rheology, gelification, gelatin, molecular structure
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