INFLUENCE OF PROCESSING CONDITIONS ON THE ANISOTROPY IN INJECTION-MOLDED THERMOTROPIC LCPS

The influence of injection-moulding conditions on the anisotropy in macroscopic properties of flat rectangular plates has been evaluated for a thermotropic main-chain liquid crystalline polymer. The anisotropic mechanical and thermal behaviour is correlated to the degree of molecular ordering as determined from X-ray diffraction. The geometry of the injection-moulded plates, such as their thickness and the thickness and shape of the sprue, as well as the injection speed, significantly affect the molecular ordering and the resulting anisotropy in, for example, Young's modulus and heat conduction. The tendencies observed are explained in terms of molecular alignment as a consequence of the combination of shear, elongational fountain flow and the elongational deformation in the sprue.