Nylon 6/carboxylic acid-functionalized silica nanoparticles (SiO 2 -COOH) nanocomposites were prepared by in situ polymerization of caprolactam in the presence of SiO 2 -COOH. The aim of this work was to study the effect of carboxylic silica on the properties of the nylon 6 through the interfacial interactions between the SiO 2 -COOH nanoparticles and the nylon 6 matrix. For comparison, pure nylon 6, nylon 6/SiO 2 (unmodified) and nylon 6/amino-functionalized SiO 2 (SiO 2 -NH 2 ) were also prepared via the same method. Fourier transform infrared spectrometer (FTIR) spectroscopy was used to evaluate the structure of SiO 2 -COOH and nylon 6/SiO 2 -COOH. The results from thermal gravimetric analysis (TGA) indicated that decomposition temperatures of nylon 6/SiO 2 -COOH nanocomposites at the 5 wt % of the total weight loss were higher than the pure nylon 6. Differential scanning calorimeter (DSC) studies showed that the melting point (T m ) and degree of crystallinity (X c ) of nylon 6/SiO 2 -COOH were lower than the pure nylon 6. Mechanical properties results of the nanocomposites showed that nylon 6 with incorporation of SiO 2 -COOH had better mechanical properties than that of pure nylon 6, nylon 6/ SiO 2 , and nylon 6/SiO 2 -NH 2 . The morphology of SiO 2 , SiO 2 -NH 2 , and SiO 2 -COOH nanoparticles in nylon 6 matrix was observed using SEM measurements. The results revealed that the dispersion of SiO 2 -COOH nanoparticles in nylon 6 matrix was better than SiO 2 and SiO 2 -NH 2

]benzenemethanaminium bromide (4-BBPDMAEMA)}, containing a photoinitiator, quaternary ammonium cations, and many C¼ ¼C double bonds, was synthesized to modify clays, such as Na þ -montmorillonite (MMT) clay, for the preparation of organicinorganic nanocomposite resins via radical photoinduced crosslinking polymerization. The structure of SBS-g-4-BBPDMAEMA was characterized by Fourier transform infrared and 1 H-NMR spectroscopy. The corresponding SBSg-4-BBPDMAEMA was found to have two functions: the capability to ionically exchange with sodium ions in the silicate gallery and the capability to synthesize exfoliated SBS/ MMT nanocomposites by the UV crosslinking of intercalation polymerization. The results from the X-ray diffraction primarily reveal that the clay platelets should have been exfoliated or completely disordered. However, the results from transmission electron microcopy confirmed that a mixture of partially exfoliated and intercalated structures presented in the nanocomposites. Dynamic mechanical thermal analysis testing indicated that the glass-transition temperature of the polybutadiene phase and polystyrene phase moved to a lower temperature. Data of thermogravimetric analysis and testing of the mechanical properties showed that the thermal stability and mechanical properties of SBS-g-4-BBPDMAEMA could be regulated by the crosslinking and content of MMT.

Nylon 6 (PA 6)/ethylene bis-stearamide (EBS)/SiO 2 -carboxylic acid-functionalized silica nanoparticles (COOH) composites were prepared by in-situ polymerization of caprolactam. SiO 2 -COOH was used to enhance the compatibility between SiO 2 and PA 6 matrix. For comparison, pure PA 6 and PA 6/EBS composites were also prepared via the same method. The PA 6/EBS/SiO 2 -COOH composites with low content of EBS and SiO 2 -COOH had greater melt-flow index (MFI) (the value of MFI increased by 50%-80%) than the pure PA 6. The results of mechanical properties showed almost no decrease in the tensile strength of PA 6/EBS/SiO 2 -COOH composites, with the bending strength decreasing by 17%-21%. However, the Izod impact strength of the PA 6/EBS/SiO 2 -COOH composites was greatly improved compared with pure PA 6, which indicated that the toughness of PA 6/EBS/SiO 2 -COOH had been greatly improved. The morphology of Izod impacted fractured surfaces of PA 6/EBS/SiO 2 -COOH was observed by scanning electron microscopy. The results revealed that the PA 6/EBS/SiO 2 -COOH composites presented a typical ductile fracture behavior with large amounts of long and large strip-like cracks. When the content of SiO 2 -COOH was 0.2 wt%, the SiO 2 -COOH particles were uniformly dispersed over the entire body of the PA 6 matrix. The results from differential scanning calorimetry indicated that the melting point (T m ), degree of crystallinity (X c ), and crystallization temperatures (T c ) of PA 6/EBS/SiO 2 -COOH composites were lower than the pure PA 6.