Preparation And Characterization Of Polyamide-6/Clay Nanocomposites

In this paper, the processing conditions of preparing polyamide-6 / clay nanocomposites by one-step in-situ intercalation polymerization method were studied, and the structure and properties of the nanocomposites were characterized in detail by means of FTIR, XRD, TEM, DSC and TG etc.In order to improve the compatibility between clay and the organic phases, organoclay was synthesized, and changes in the layer structure of clay before and after the intermixing investigated. The cation exchange capacity is 90~120mmol/100g and the content of montmorillonite larger than 60% of clay was chosen in experiment. The clay was treated with using water and auxiliary dispersing agent D, then organoclay was prepared from sodium type clay by cation exchange with protonating agent A, main organizing agent C and auxiliary organizing agent B, which made clay change from hydrophilic to lipophilic, could dewatering more than 90% by the mechanical dewatering method. FTIR analysis before and after of the treated clay showed that exist the line of deformation vibration of -CH2- at 1460cm-1 and the line of stretching vibration of C-H at 2939cm-1 in treated clay. It was indicated that organic compound have been intercalated into clay silicate layers form an organoclay. Spacing of layers of clay was detected using XRD and was observed to have increased from 0.99nm to 1.58nm for organoclay and there is no trace of X-ray diffraction peaks for nanocomposites. The above treated organoclay was mixed with the melted -caprolatam, ?-caprolatam could intercalate into clay interlayer. Subsequently the -caprolatam could polymerize in the organoclay interlayer without catalyst for 2~6h at 250癈 to 260, then vacuum reaction 15~30min.FTIR and XRD experimental results indicated that the crystal form of polyamide-6in nanocomposites was mainly r crystal form. It has been found that the presence ofclay influences the crystal form of polyamide-6 in nanocomposites with increasing of clay content in nanocomposites, the content of y crystal form increased. The XRDpatterns and the TEM images of the nanocomposites showed that the clay layers were exfoliated into nanometer size and dispersed uniformly in the polyamide-6 matrix. Molau experiment indicated that the sample of PA6/clay nanocomposites can suspend stably in formic acid solution. It is found that the affinity between the organoclay and PA6 matrix is very good.The results of XRD and DSC show that the nanocomposites have a crystal structure and crystallization behavior different from that of pure PA6. DSC risingscanning curves show that the nanocomposites have melt double-peak, it was explained that the addition of clay promote y crystal form of PA6 formed. While coolingscanning curves show, with the increment of the clay content in the nanocomposites, that heighten the crystallization temperature of PA6, lost the supercooling degrees, narrowed the width of the crystalline peak, increased the crystalline degrees, decreased crystallization rate parameter K, reduced the crystallization activation energy and half crystallization time of nanocomposites than that of pure PA6. According to the experimental results we conclude that organoclay play the role of iso-phase nucleation in the PA6 matrix, thus enhanced the crystallization rate of PA6 obviously.The results indicated, when compared to the pure PA6, that the thermal stability of nanocomposites was enhanced, decomposition onset temperature was increased slightly, but heat distortion temperature can be greatly improved by addition of low clay loading. Mechanical property testing results indicated that the properties of nanocomposites are superior to those of PA6. This is due to nanoscale effect and the strong interaction between PA6 matrix and clay interface as revealing in XRD, TEM and Molau testing. The rheological behaviors of nanocomposites and PA6 were studied. The results showed that the nanocomposites exhibits similar shear thinning behavior as pure PA6, belonged to pseudoplastic and non-Newtonian fluid, the non-Newtonian index was...