Attempts to extend the IPN technology to liquid crystalline polymer (LCP) systems have been made in search for a new approach for enhancing the compatibility of liquid crystalline polymer with engineering thermoplastics. A new type of interpenetrating polymer network based on liquid crystalline polymer : semi-interpenetrating liquid crystalline polymer network comprising liquid crystalline polymer PET/60PHB (LCP) and crosslinked polystyrene (PS) (for short: semi-ILCPN LCP/PS) has been successfully prepared. The compatibility and thermal properties of the semi-ILCPN LCP/PS with different amount of crosslinking agent were investigated by FTIR, SEM, DSC, and TGA, respectively. Furthermore, the possible application of the semi-ILCPN LCP/PS as a new kind of compatibilizer in PPO/LCP blends was also studied and discussed. Well-compatibilized PPO/LCP composites with considerably improved mechanical properties were obtained. (C) 2000 John Wiley & Sons, Inc.