聚醯胺46/氧化石墨烯及聚醯胺612/氧化石墨烯複合材料之結晶行為與物理性質研究

Abstract

The chemically modified graphite oxide was characterized using FTIR and XRD method. Both results indicate that the presence of oxidation functional groups on the surface of graphite oxide might enlarge the interlayer spacing of graphite. The ratio of ID/IG for graphite oxide determined using Raman spectrometer was increased, which could be well dispersed into graphene oxide through ultrasonication process. Therefore, polyamide 46 (PA46)/graphene oxide (GO) and polyamide 612 (PA612)/graphene oxide nanocomposits were successfully fabricated in this study by solution mixing PA46 and PA612 into chemically modified graphite oxide through ultrasonication process. The effect of GO on the microstructure, crystallization behavior and physical properties were investigated. Both TEM and XRD results show the graphene oxide was well distributed into polyamide matrix. The crystallize structure of polyamide did not change with the incorporation of GO. The crystallization behavior of PA46/GO nanocomposite were investigated using DSC. The addition of 5wt% GO into PA46 matrix could induce hetergeneous nucleation and enhance the crystalline growth rate of PA46 crystalline. The incorporation of 5wt% GO into PA46 matrix could reduce the activation energy from 742.8 kJ/mol for PA46 into 588.0 kJ/mol. The equilibrium melting temperature of 5wt% PA46/GO nanocomposite is reduced from 335.7℃ for neat PA46 matrix into 323.9℃, suggesting that the crystalline structures of PA46/GO nanocomposites was less perfect than that of the PA46 matrix. The POM data of nanocomposite revealed that the addition of GO into PA46 matrix could increase the nucleation density and reduce the spherulitic size. The folding energy of PA46/GO nanocomposites decreased from 3.71×103 erg2/cm4 for PA46 into 2.08×102 erg2/cm4 for 5wt% PA46/GO nanocomposites. The storage modulus of nanocomposites obtained using DMA increased from 8.9×108 Pa for PA46 into 1.8×109 Pa for 5wt% PA46/GO nanocomposite. The result suggests that the incorporation of GO into polymr matrix could reduce the polymr chain movement within the gallery of GO sheets. The crystallinity of PA46/GO nanocomposite is increased from 46.7% for neat PA46 matrix into 54.1% for 5wt% nanocomposite, suggesting that the addition of GO into PA46 matrix could induce hetergeneous nucleation and thus increased the crystallinity. DSC isothermal results of PA612/GO nanocomposites revealed that the addition of 3wt% GO into PA612 matrix could induce hetergeneous nucleation and enhance the crystalline growth rate of PA612 crystalline. Addition of 5wt% GO into PA612 matrix causes more steric hindrance, thus reduce the transportation ability of polymer chains during crystallization process. The incorporation of 3wt% GO into PA612 matrix could reduce the activation energy from 391.6 kJ/mol for PA612 into 308.3 kJ/mol, and then increase to 331.2 kJ/mol as the loading of 5wt% GO. This result indicates that the addition of 5wt% GO into PA612 matrix reduced the transportation ability of polymer chains during crystallization. The equilibrium melting temperature of 5wt% PA612/GO nanocomposite are reduced from 222.6℃ for neat PA612 matrix into 214.7℃, suggesting that the crystalline structures of PA612/GO nanocomposites was less perfect than that of the PA612 matrix. The POM data of nanocomposite revealed that the addition of GO into PA612 matrix could increase the nucleation density and reduce the spherulitic size. The folding energy of PA612/GO nanocomposites decreased from 1.71×102 erg2/cm4 for PA612 into 7.32×101 erg2/cm4 for 3wt% PA612/GO nanocomposites, and then increase to 9.24×101 erg2/cm4 as the loading of 5wt% GO, thus a reduces the transportation ability of polymer chains. The storage modulus of nanocomposites obtained using DMA increased from 1.03×109 Pa for PA612 into 1.57×109 Pa for 5wt% PA612/GO nanocomposite. The result suggests that the incorporation of GO into polymr matrix could reduce the polymr chain movement within the gallery of GO sheets. The crystallinity of PA612/GO nanocomposite is increased from 30.4% for neat PA612 matrix into 32.0% for 3wt% nanocomposite, suggesting that addition of GO into PA612 matrix could induce hetergeneous nucleation and thus increased the crystallinity. As the loading of 5wt% GO into PA612 matrix could decrease the crystallinity to 30.8%, which might due to the limitation of polymer chain movement for crystallization.