Effect of crosslinking agents (basic chromium sulfate and formaldehyde) on the thermal and thermomechanical stability of rat tail tendon collagen fibre

The role of covalent and coordinate covalent crosslinks on the thermal and mechanical properties of rat tail tendon (RTT) collagen fibre has been studied. The tendons were tanned with formaldehyde (HCHO) and basic chromium sulfate (BCS). Thermal properties of the crosslinked fibres were studied using shrinkage temperature, hydrothermal isometric tension behaviour and differential scanning calorimetry (DSC). Mechanical properties were analysed using tensile strength and stress relaxation behaviour. The results show that BCS tanned RTT exhibits a marked increase in the peak temperature and enthalpy changes when compared to both native and HCHO tanned RTT. This may be due to a net increase in the number of intermolecular crosslinks arising from both electrovalent and coordinate covalent interactions during BCS tanning. After treatment with urea there is a decrease in the peak temperature and the enthalpy changes of BCS tanned RTT fibres suggesting alterations in the secondary structure of collagen are possible even after tanning. An increased long range order is seen in the case of chromium tanned fibres in comparison to HCHO treated analogue.