탄소나노섬유가 폴리케톤의 용융결정화거동에 미치는 영향

Abstract

We report the influences of carbon nanofiber (CNF) on the melt-crystallization behavior and structures of polyketone (PK) composites, which were manufactured by a solution blending process. For this purpose, melt-crystallization experiments of neat PK and its composites, including 0.5 and 1.0 wt% CNFs, were carried out at different isothermal temperatures by using a differential scanning calorimeter and the results were analyzed using the Avrami equation. For all neat PK and PK/CNF composites, the Avrami index n remained unchanged, regardless of the isothermal crystallization temperatures (<TEX>$T_c$</TEX>), whereas the rate constant K and the inverse of crystallization half-time (<TEX>${t_{1/2}}^{-1}$</TEX>) increased noticeably with decreasing <TEX>${T_c}^{\prime}s$</TEX>, indicating faster melt-crystallization rates at lower <TEX>${T_c}^{\prime}s$</TEX>. It was further revealed that the melt-crystallization rates of PK/CNF composites were far greater than those of neat PK owing to the nucleating effect of CNF to the melt-crystallization of PK and that the composite with 1.0 wt% CNF exhibited slightly better crystallization rates, compared to the composite with 0.5 wt% CNF. Polarized optical microscopic images and X-ray diffraction patterns also support that CNF contributes to accelerate the melt-crystallization rates of PK without influencing the crystal structure of PK <TEX>${\beta}$</TEX>-form.