Blends of liquid crystalline polyesters and amorphous polymers

It is shown that blending a TLCP with thermotropic polymer results in a dramatic decrease in the melt viscosity. Under proper processing conditions, the TLCP droplets can deform and elongate according to deformability of a suspension medium. The viscosity ratio plays a key role in determining the form of microdroplets of the liquid crystalline phase. This means that the blend has to be processed in a suitable temperature range, in order to control the viscosity ratio of the different phases. In this case the liquid crystalline phase can segregate as fibers with high aspect ratio in the host matrix. For the mechanical properties of the spun blend, the usual models valid for the composites can be succesfully applied. However, attention should be devoted to the evaluation of the modulus of the oriented liquid crystalline phase in the blend, that in many cases is lower if compared to that of the pure oriented mesophastic polymer. The processing technique proposed for toughening brittle matrices with Liquid Cristalline Polymers looks to be promising.