Thesis (M.Eng.)--Chulalongkorn University, 1998

The properties of the blend systems of poly (bisphenol-A-carbonates) (PC) with two low molar mass thermotropic liquid crystals in cyclohexyl-biphenylcyclohexanes group (CBC33 and CBC53) at low concentration range of low molar mass liquid crystals were studied in this work. The blends were prepared by melt mixing at 3 different concentrations (0.25, 0.5 and 1 percent of liquid crystals). The shear viscosities of pure PC and their blends were investigated using a capillary rheometer and the glass transition temperatures were measured by Differential Scanning Calorimeter (DSC). Experimental results showed that the viscosity of the blends with only small weight fraction (1 percent) of low molar mass liquid crystals is about 90 percent lower than that of the pure polycarbonates. DSC thermograms also show the decreasing in the glass transition temperatures of PC. This indicates that low molar mass thermotropic liquid crystals can act as plasticizers for PC.