The effect of crystallinity and water absorption on the dynamic mechanical relaxation behaviour of polycaprolactone

The effect of the degree of crystallinity on the dynamic mechanical relaxation behaviour (flexural storage modulus and loss tangent) of polycaprolactone has been investigated. The degree of crystallinity was found to determine the temperature of the alpha-relaxation process and the relaxation strength of the beta-relaxation. The increase in temperature of the alpha-process has been ascribed to constrainment of the amorphous regions of the sample by the crystallites. In accordance with the observed effect of the degree of crystallinity, the origin of the dynamic mechanical beta-relaxation has been ascribed to the amorphous regions of the material. The intensity of the beta-process has also been found to depend on the moisture content, becoming more prominent when moisture is present. In addition, moisture has been shown to penetrate the crystalline regions of the sample over a relatively short timescale, as shown by infrared spectroscopy. (C) 2004 Society of Chemical Industry.