ABSTRACT
ABSTRACT: Characterizing the effects of cross-linking level and kinetics on the mechanical properties of rubber, especially viscoelasticity, provides information of importance to better understand and predict its final mechanical properties. Classically, the effects of cross-linking on the mechanical properties are investigated with a rheometer. Typical results give the evolution of elastic properties of rubber in the solid state with respect to time or to the cross-linking level. The frequency of the mechanical loading applied is generally a few hertz. In the case where the rubber is initially in the liquid state, such as some silicone rubbers, this type of characterization is not suitable anymore. In this study, a new characterization technique based on the Quartz Crystal Microbalance (QCM) principle has been developed in order to characterize the viscoelastic properties (elastic and viscous moduli) of a silicone rubber during cross-linking, i.e. from the liquid (uncross-linked) to the solid (final crosslinked) state. The device consists in a Thickness-Shear Mode (TSM) resonator generating ultrasonic waves, which provides viscoelastic properties of a material in contact with its surface from an electrical impedance analysis. In contrast to other characterization tools, it makes possible the continuous and non-destructive characterization of viscoelastic properties from a small material volume, under 1 mL. Moreover, frequencies at which these properties are characterized are of the order of magnitude of the megahertz, which provides very complementary results to classical characterization, rather in the order of the hertz.
