Viscoelastic behavior of formaldehyde and basic chromium sulfate-crosslinked collagen

Abstract

Rat tail tendon (RTT) collagen has been crosslinked with 1% basic chromium sulfate (BCS) at pH 3.2, and 2, 4, 8, and 10% formaldehyde (HCHO) at pH 5 and pH 8. The viscoelastic behavior (such as stress relaxation behavior for BCS and HCHO-tanned RTT) has been studied in water and 6M urea at different temperatures. The total rate of relaxation has been divided into fast and slow components, and computed using the two-term model and nonlinear least-squares fit. The rate of relaxation for crosslinked RTT is less than the native one. Activation energy at absolute zero has been computed using k ϭ AT m e ϪE0/RT and nonlinear least-squares fit. The activation energy increases for crosslinked RTT than the native one. This is consistent with the observed rate constant values. This may be due to the additional stability imparted to RTT collagen by coordinate covalent and covalent crosslinks through BCS and HCHO, respectively.

Role of Secondary Structure on the Stress Relaxation Processes in Rat Tail Tendon (RTT) Collagen Fibre

“…The treatment of stress relaxation data for basic chromium sulfate and formaldehyde-crosslinked RTT and native RTT in aqueous alcoholic media have already been explained briefly. [17,32] Since the matrix structure of collagen exhibits anisotropic properties and high levels of inter-and intramolecular organisation, it is not sufficient to treat relaxation in terms of single element model. It is worthwhile to investigate some useful empirical models to describe the stress relaxation data of collagen fibres.…”

“…[15,16] Recently we have investigated the viscoelastic behaviour of formaldehyde and basic chromium sulfate-crosslinked rat tail tendon using stress relaxation experiments. [17] It is known that collagenous tissues undergo dimensional changes under the influence of temperature, solvents, pH conditions, crosslinking agents, mechanical and chemical stress. [18 -23] The viscoelastic properties of polymers in general, and collagen in particular, are influenced by temperature.…”

Effect of hydrogen‐bond‐breaking reagent (urea) on the dimensional stability of rat tail tendon (RTT) collagen fiber

“…(1): where A 0 and B 0 are the preexponential factors and k 1 and k 2 are the fast and slow relaxation rate, and with Nonlinear least‐squares fit with a Hewlett‐Packard work station and standard packages 26. This was explained elaborately elsewhere 27, 28…”

Development of aldehyde and similar-to-aldehyde tanning agents

“…Therefore, it is easier to understand the role of the formation of ether bonds and polyformaldehyde. [18][19][20] As a tanning agent, formaldehyde has the highest tanning power among aldehydes thus far, and the T s of the tanned leather can reach 87 C. Formaldehyde-tanned leather is white and has a good ability to withstand the action of water, sweat, and light and can be plasticized and softened with oil or grease; however, it lacks fullness. The isoelectric point of formaldehyde-tanned leather is below 4.0, and the absorption of anionic materials is low in the subsequent processing.…”