Preparation and Properties of PVA Composites Containing Homogeneously Dispersed MWNTs

This paper presents a novel and versatile fabrication method for the preparation of poly(vinyl alcohol) (PVA) composites containing completely dispersed multi-walled carbon nanotubes (MWNTs). Prior to mixing with PVA, the MWNTs were debundled by mixing with sugar syrup. The predispersed MWNTs were washed with water and filtered to remove the sugar syrup. Subsequently, they were mixed with PVA in water, followed by a solution casting process. Microscopic images of the PVA composites revealed that the dispersion was significantly better than those prepared with crude nanotubes. The dynamic viscosity of the PVA solutions increased as the MWNT content increased. Specifically, an abrupt increase in the yield stress was observed in the Casson plot with MWNT content between 5 and 10 wt%. Up to 1 wt% MWNT loading, there was no noticeable effect in the thermal stability, while further addition lowered the degradation temperature. The stress-strain curves showed a more pronounced yield and post-yield drop with increasing MWNT content up to 1 wt% loading, whereas further addition of MWNTs weakened the yield behavior. At only 1 wt% loading, the yield strength corresponded to the breaking strength. The tensile strength and the modulus of the PVA composites increased up to 1 wt% nanotube loading and decreased at higher nanotube contents. In addition, the elongation at break of the PVA composites decreased at a nanotube loading of ${\geq}0.5wt%$.

균일하게 분산된 MWNTs를 함유한 PVA 복합체의 제조와 물성