Jong-Ryul Park

Effect of Aromatic Ring Content on the Properties of Liquid Crystalline Copolyesters

The liquid crystalline copolymers were synthesized through direct polycondensation using 4-[4-(4-hydroxyphenoxy)butoxy]benzoic acid (HBBA) and p-hydroxy benzoic acid (HBA) as monomers. The structure and properties for synthesized copolymers were investigated by H-NMR, FT-IR, differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and polarizing optical microscope (POM). As result of investigations, inherent viscosities (ηinh) of polymers were measured as 0.77~1.60 dL/g in phenol/p-chlorophenol /1,1,2,2-tetrachloroethane (25/40/35=w/w/w). Except for P-80, the ranges of the transition and mesophase temperature of copolymers were increased with increasing the amount of HBA. These properties of polymers were presumably due to increasing of the irregularity and rigidity of polymer chains.

Study on the Isothermal Crystallization Behaviors of PEN/TLCP Blends

Abstract: The isothermal crystallization behaviors of blends of poly(ethylene naphthalate) (PEN) and a thermotropic liquidcrystalline polymer (TLCP) were investigated by differential scanning calorimetry (DSC) as functions of crystallization tem-perature and blend composition. Avrami analyses were applied to obtain information on the crystal growth geometry andthe factors controlling the rate of crystallization. The crystallization kinetics of the PEN/TLCP blends followed the Avramiequation up to a high degree of crystallization, regardless of crystallization temperature. The calculated Avrami exponentsfor PEN/TLCP revealed three-dimensional growth of the crystalline region in each blend. The crystallization rate of eachblend increased as the crystallization temperature decreased, and decreased as the TLCP content increased. The crystalli-zation of PEN in the blend was affected by the addition of TLCP, which acts as a nucleating agent.Keywords: Avrami equation, isothermal crystallization kinetics, nucleating agent, PEN/TLCP blend

Synthesis and Properties of Semi-flexible Liquid Crystalline Polyesters with Rigid Lateral Group

Jong-Ryul Park, Eung-Jae Lee, Doo-Soo Yoon, Moon-Soo Bang and Jae-Kon Choi Division of Advanced Materials Science and Engineering, Kongju National University, Cheonan 330-717, Korea Dept. of Bioenvironmental & Chemical Engineering, Chosun College University of Science & Technology, Gwangju 501-744, Korea Dept. of Biochemical & Polymer Engineering, Chosun University, Gwangju 501-759, Korea (Received November 6, 2013, Revised November 13, 2013, Accepted November 18, 2013)