A HIGH-PRESSURE-CELL FOR OPTICAL MICROSCOPY AND MEASUREMENTS ON THE PHASE-DIAGRAM OF POLY(DIETHYLSILOXANE)

A new high-pressure cell as useful equipment for a polarizing microsco pe is described. Measurements in a temperature range between -40 and 270 degrees C under hydrostatic pressures up to 300 MPa allow for exam ple the observation of polymer morphology and phase transitions. In ad dition to a documentation on video and photograph, respectively, the c omputer-controlled light intensity measurement offers the possibility of a quantitative analysis. Investigations on the phase diagram of pol y(diethylsiloxane) have been carried out and show, that the transition temperature from mesophase to isotropic melt decreases with increasin g pressure for pressures above 160 MPa. (C) 1998 American Institute of Physics. [S0034-6748(98)04004-0].