Affiliations: [a] Department of Biology, Faculty of Science, Osaka City University, Sumiyoshi-ku, Osaka 558, Japan | [b] Laboratory of Biology and Chemistry, Tezukayama College, Gakuen-minami, Nara 631, Japan
Abstract: In practical measurement of stress-relaxation, a certain length of time is required to apply the initial stress to a specimen. We refer to this process as pre-extension. In the stress-relaxation analysis of the plant cell wall which we developed, a wall specimen is stretched at a constant rate in pre-extension. The condition of pre-extension, such as the length of the pre-extension period, affects the subsequent stress-relaxation process. Thus, the stress-relaxation time spectrum calculated directly from the stress-relaxation process is an approximation. In this study, the condition during pre-extension was formulated in a stress-relaxation function and the stress-relaxation time spectrum, H(τ), was calculated as
H(τ)=b·{exp(−T0/τ)−exp(−Tm/τ)}/{r·τ·(l−exp(−Tp/τ))}
where T0 and Tm are the minimum and maximum relaxation times, τ is the relaxation time, b is the relaxation rate, r is the extension rate in pre-extension and Tp is the pre-extension time. The effect of the pre-extension condition on the spectrum is discussed.
