Poly(benzoxazole-imide) 공중합체의 합성 및 특성에 관한 연구

Abstract

In this work, poly(benzoxazole-imide) precursor copolymers containing oligo(oxyethylene) substituent groups and imide ring in the main chain were obtained by the direct polycondensation reaction. The inherent viscosities of PHAs were tested using ubbelohde viscometer. They were in the range of 0.86～1.09 dL/g at 35℃ in DMAc or DMAc/LiCl solvent. In solubility test, except for PHA 6, all PHAs were soluble in aprotic solvent: NMP, DMAc, DMF, DMSO. However, PBOs were only partially soluble in sulfuric acid. In DSC thermograms, PHAs were showed endothermic peaks in the range of 249～295℃. We identified that PHAs were converted to PBO by the thermal cyclization reaction in the range of 249～295℃. The temperatures of 10% weight loss of the PBOs were recorded in the range of 344～623℃ and char yields showed 32.7～60.6% values at 900℃. In order to compare mechanical properties of PHAs, we have measured the initial modulus, tensile strength, and elongation. The initial modulus, tensile strength, and elongation of all PHAs were in the range of 0.29～3.47 GPa, 8.32～69.84 MPa, and 4.08～19.60%, respectively.