| In this paper, two kinds of bran-new quaternary phosphonium salt organic montmorillonites were synthesized by using sodium montmorillonite as raw material, quaternary phosphonium salts (DTPB and BTPB) as intercalating agents and distilled water as the solvent. The best conditions of the intercalating reactions were determined by mass loss. The structures of modified montmorillonites were characterized by means of X-ray diffraction and FTIR. The experimental results showed that molecular chain of quaternary phosphonium salt were intercalated into the layers of montmorillonite, and the space of layers was increased. TG experiment showed that the thermal stabilization of quaternary phosphonium salt organic montmorillonite was higher, in comparison of that of quaternary ammonium salt organic montmorillonite; Sedimentation experimental results showed that modified montmorillonite has better dispersibility and swelling property in organic solvents containing benzene ring.PA6/MMT composites were prepared by using PA6 and montmorillonite as raw materials with the different ratio by means of the melting intercalation in the two screw extruder and injection molding punch. In addition, structures, mechanical properties, thermal degradation, flammability and crystal properties of the composites were measured and characterized.The data of X-ray diffraction showed that PA6 polymer chains were intercalated into layers of OMMT. TEM observed that OMMT was randomly dispersed in the PA6 matrix as nano-size and some were stripped. Molau dissolution experiments also indicated that PA6 polymer chains were intercalated into layers of OMMT and the interaction was strong. The SEM results demonstrated that OMMT improved the interfacial compatibility and the nanocomposites were shown as toughness rupture.The data of mechanical properties showed that OMMT enhanced tensile strength, flexural strength and Notched Izod impact strength of PA6 composites. The mechanical properties of composites varied with the content and type of modified montmorillonites. The mechanical properties of PA6/OMMT were superior to PA6/Na-MMT. Quaternary phosphonium salt organic montmorillonites enhanced the Notched Izod impact strength at a low loading, which was higher than that of quaternary ammonium salt organic montmorillonite.Kinetics of thermal degradation results indicated that the activation energy of thermal decomposition of PA6/OMMT was more than that of pure PA6; Thermal degradation behavior showed that montmorillonite made the temperature of initial decomposition appear earlier; OMMT reduced the mass loss rate of PA6 and quaternary phosphonium salt organic montmorillonite nanocomposite appeared the second peak after 650℃, but few char residues.The data of cone calorimeter indicated that montmorillonites made the rate of themal cracking of carbon frame decrease obviously and increased the ignition time, which showed that the new montmorillonite had flame retardancy. The new montmofillonite increased the smoke production rate and total smoke production, which attributed to the high benzene content of quaternary phosphonium salt. The flame retardancy mechanism was conferred that the lays of OMMT obstructed heat exchange in condensed phase, which suggested from the configuration of composites.The effects of montmorillonite on the nonisothermal crystallization behaviors of PA6/montmorillonite nanocomposites were studied by DSC. Nonisothetmal crystallization kinetics parameters of PA6/montmorillonite were calculated by using Jeziorny and Mo equation. The presence of montmorillonites in the composites made the crystallization temperature and crystallization rate rise. The existence of montmorillonite can change the nucleating mechanism and growth style of PA6's crystallization process. The pictures of POM showed that the presence of montmorillonite made the crystal size diminish obviously and made the integrality of crystal reduce.
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