THE VISCOELASTIC PROPERTIES OF CONFINED POLYMER LAYERS

We have designed, built and are operating an apparatus for the measure ment of the viscoelastic properties of confined polymer layers. Such l ayers occur in colloidal dispersions, ceramic greens and so on, and co ntrol many of the properties of such systems. A piezoelectric device i s used to apply an oscillatory motion to the confined layer. The motio n is transmitted across the gap to a receiver piezoelectric crystal, a nd amplified. The viscoelastic properties of the layer can be obtained from the in-phase and out-of-phase components of the signal. Adsorbed copolymers in an organic medium were used for the investigation. Thre e distinct regions of behaviour were observed. At high compression the material was elastic in its response, at low compression viscous, and at intermediate distances viscoelastic.