The low‐temperature mechanical relaxation of elastin. I. The dry protein

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Abstract
The low‐temperature relaxation of native ox Ligamentum nuchae elastin and of two purified elastin samples has been investigated in the dry state by means of the Rheovibron DDV II viscoelastometer, at the fixed frequencies of 3.5, 11, 35, and 110 Hz. Besides the glass transition at about 200°C, a relatively strong secondary loss‐tangent peak, whose activation energy is about 13 kcal/mol, is found for all samples below room temperature. The peak maximum is at −71°C for the 3.5‐Hz frequency. On the basis of its location, intensity, and width, it is attributed to a main‐chain relaxation of the pure protein. When suitable reduced variables are used, the loss‐tangent‐temperature curves obtained at different frequencies can be satisfactorily superimposed to give a master curve. Comparison of the data with the prediction of a semiempirical viscoelastic model can also be considered satisfactory.