MELT INTERCALATION OF POLYSTYRENE IN LAYERED SILICATES

We have studied the melt intercalation of polystyrene into organically modified sodium bentonite, a layered, mica-type silicate, using a var iety of techniques. Wide-angle X-ray scattering experiments on polymer /silicate hybrid samples demonstrate that intercalation of polymer cha ins leads to an similar to 25% increase in the spacing between silicat e layers. The magnitude of this increase, compared with the radius of gyration of the melt polymer, implies a flattened conformation of chai ns in the galleries. Low voltage scanning electron microscopy reveals voids in the intercalated hybrid matrix that correspond to regions whe re pristine polymer was present in the physical mixture of polymer and silicate before intercalation. Differential scanning calorimetry show s that only unintercalated polymer contributes to the measured glass t ransition trace, so that the magnitude of the trace is diminished upon intercalation. (C) 1996 John Wiley & Sons, Inc.