Measurement of stress and strain during tensile testing of gellan gum gels: effect of deformation speed

Tensile tests were carried out on gellan gum gels of concentration 2% in order to observe the relation between deformation speed and deformation properties such as tensile modulus and rapture strain. The primary objective of this experiment is to show the validity of the measurement for the actual strain and strain rate during tensile tests. The tensile modulus decreased with decreasing deformation speed, showing the viscoelastic character of the gel, while the stress-strain curve was linear. The results were interpreted in terms of linear viscoelasticity theory. The instantaneous modulus was calculated and compared with the storage modulus found in the literature. A guide value of the relaxation time was also calculated and shown to be much larger than the observation time. (C) 2002 Elsevier Science Ltd. All rights reserved.