The dynamic mechanical analysis of hydrogel elastomers

An internal liquid bath which can be fitted into the furnace of a Perkin-Elmer DMA-7 has been developed. This new internal liquid bath allows the samples to be tested by dynamic mechanical analysis (DMA) in a liquid medium, not only under isothermal condition but also in the temperature scan mode. It overcomes problems such as sample dehydration when using DMA for hydrogel materials and soft tissues and is superior to the external liquid bath which is normally difficult to run in the temperature scan mode. A plot of program temperature versus sensor temperature, demonstrates that introducing the extra mass of the liquid bath and the liquid medium does not interfere the system when operating in the temperature scan mode. DMA equipped with this new liquid bath has been used in studying poly(vinyl alcohol) (PVA) hydrogel samples; the results are discussed.