The viscoelastic properties of wool and the influence of some specific plasticizers

Abstract

Abstract:The relaxation behaviour of Lincoln wool fibres in water and in three short chain aliphatic alcohols was measured. Applying a two phase model including a relaxation function based on a log-normal distribution of relaxation times a good systematic description of the data was found. The application of the model to the relaxation curves of wool fibers in the alcoholic media showed the invariance of the shape of the relaxation function, its shift on the log-time scale and the change of the elastical properties of the morphological components of the wool fibre depending on the aliphatic chain length of the alcohols. The importance of the apolar interactions for the elastic and viscoelastic properties of the morphological phases in the wool fibre is discussed.

Thermal denaturation and structural changes of α-helical proteins in keratins

“…This effect is due to the pronounced plasticizer action of water on the matrix material (Haly and Snaith, 1967;Wortmann, 1987;Cao and Leroy, 2005;Wortmann et al, 2006b). Fig.…”

Humidity‐dependent bending recovery and relaxation of human hair

“…In analogy to the case of extensional relaxation14, 19, 28 time‐dependent bending stiffness is described by: …”

“…Previous investigations for α‐keratinous materials14, 19, 28, 29 and various other polymers30, 31 have successfully made use of the cumulative log‐normal distribution (CLND) as relaxation function. An obvious, practical disadvantage of the CLND function is the lack of an analytical form, necessitating the use of numerical approaches.…”

“…The relaxation of the matrix contribution to the overall fiber bending stiffness is very fast in water,15, 28 where hair is well above its humidity‐dependent glass transition 13. This removes all effects of aging and yields effectively Δ B = 0 after the wetting of the bent fibers during the initial step of the experiment.…”

Temperature memory effect/triple-shape memory effect in niti shape memory alloys and shape memory effect in keratin

“…According to Wortmann [158] In the intermediate filaments/matrix model, the matrix is mainly consisted of noncrystalline component, which is accessible to water. It has been found that the modulus of matrix decreases significantly at the presence of moisture [159,163], and such a phenomenon is attributed to the strong plasticizing effect of water on matrix [164][165][166][167]. In the contrast, the intermediate filaments contains α-helical component and is highly organized [168].…”