STRUCTURE DEVELOPMENT OF A POLYBUTADIENE POLYISOPRENE BLEND DURING SPINODAL DECOMPOSITION - COMPARISON BETWEEN LIGHT-SCATTERING AND OPTICALMICROSCOPY/

The typical interconnected bicontinuous percolation structure of a cri tical 50/50 wt % polybutadiene (PB)/polyisoprene (PI) mixture was char acterized in detail by the structure function of a light scattering ex periment and by statistical image processing of optical microscope ima ges. The time development of the interdomain distance and the local ra dius of the curved interface in the late stage of the spinodal decompo sition are obtained for the first time for the same system by both met hods and are found to be in good agreement. PB/PI blends are systems w ith a lower critical solution temperature (LCST). The critical point w as varied within a wide temperature range by changing the 1,2 content of the PB. For optical microscopy, the structure was fixed by photo-cr oss-linking and the optical contrast was achieved in a second step by selective staining of the PI phase by exposing the sample to iodine va por.