Reactive extrusion of PET (poly(ethyleneterephthalate)) and LCP (liquid crystalline polymer) blends

The 'In-Situ' compatibilizatian for PET/LCP blend via transesterification reactions in a twin screw extruder having a very short residence time was investigated through thermal, theological and mechanical studies. Inclusion of small amount of LCP enhanced the crystallization rate of PET matrix. They acted as a nucleating agent. LCP lowered the blend viscosity above Tcn (crystalline-nematic transition temperature), working as a processing aid. However,the addition of dibutyltindilaurate (DBTDL) as a reaction catalyst was found to increases the viscosity of the blends, diminish the size of the dispersed phase, enhance its adhesion with the matrix and lead to increase of mechanical properties of two immiscible phases. Hence DBTDL is helful to produce a reactive compatibilizer by reactive extrusion at the interface of this polyester blend system. The optimum catalyst amount turned out to be about 500ppm when the reaction proceeds in 90/10 PET/LCP polyester blend systems. The structural change of reactive blend was identified by H-1 NMR and wide angle X-ray diffraction patterns.