Mechanical response of reconstituted, freeze-dried collagen under compressive loads

The mechanical response under uniaxial compression of collagen discs, made from freeze-dried collagen reconstituted at acid pH, was investigated at 22, 29.5 and 35 degrees C. The pH during compression was maintained at the physiological level of 7.4. The fluid transport model developed by Bert (1970) was fitted to the data. Assumptions, made in the development of the model, were tested and the range of reliability of the model is discussed. The two fitting parameters of the model were found to be stronger functions of hydration than was previously reported. The compressive response of collagen was found to be only weakly influenced by temperature. At 35 degrees C there was evidence of thermal degradation. Some creep was noted at times greater than five half-times, but no attempt was made to quantify it.