MISCIBILITY AND LIQUID-CRYSTAL BEHAVIOR OF P-AZOXY ANISOLE IN POLYMERBLENDS

The phase behaviour of two polymer/liquid crystal blends has been inve stigated by DSC and optical microscopy. In one case, blends of poly(oc tadecylethylene) (POE) and p-azoxyanisole (PAA) are found almost immis cible below the isotropization temperature of the liquid crystal. The crystallization process of PAA in the blends takes place with a sporad ic growth of dendritic structures determined by the dispersion of the nematic phase in the molten polymer. In the other case, blends of Poly (biphenylyloxyexylacrylate) (PBHA) and PAA display a different phase b ehaviour indicating partial miscibility of the two components at tempe ratures above the melting point of the polymer. At high concentrations of PAA a nematic phase dispersed in a isotropic liquid mixture of pol ymer and Liquid crystal is observed. These results are accounted for b y the different side-chain structure of the polymer components.