DIELECTRIC CURE CHARACTERIZATION OF MODEL ELASTOMERS

Isothermal dielectric properties of poly(dimethylsiloxane) (PDMS) networks during cure were studied at room temperature with emphasis on the effect of catalyst concentration. The frequency range employed was 10(-1) to 10(5) Hz. The dielectric response is sensitive to a change in catalyst levels as this was evidenced by the change in the values of the logarithm of the loss factor log epsilon. We attribute these changes to dipolar and ionic contributions. A profile of the cure reaction of model elastomers may readily be obtained by using a combitiation of microsensors and time-domain dielectric spectroscopy. The results obtained show that the catalyst concentration affects both crosslinking and chain extension reactions. However, for the typical catalyst concentration at which typical networks are prepared, the crosslinking reaction is the dominant effect.