Properties of phosphorus-containing thermotropic liquid crystal copolyester/poly(ethylene terephthalate) blends

A thermotropic liquid crystal copolyester containing phosphorus (PLCP) with high flame retardancy (limiting oxygen index, 70%) has been synthesized and blended with PET. The flame retardancy, mechanical properties, crystallization and thermal degradation behaviour of PET/PLCP blends have been investigated via different methods such as LOI values and UL-94 rating, differential scanning calorimetry (DSC), wide-angle X-ray diffractometry (WAXD) and thermogravimetric analysis (TG). PLCP can dramatically improve the flame retardancy and the melt dripping behaviour of PET. The tensile strengths of PET/PLCP blends increase with the increase of PLCP content. PLCP in PET/PLCP blends acts as a nucleating agent for PET and accelerates its crystallization. PLCP widens the temperature range of PET decomposition. The residues of PET/PLCP blends at high temperatures increase with the increase of PLCP content.