Regulation Of Micro - Morphology Of Montmorillonite Particles Under Supercritical Conditions And Its Effect On Performance Of PBS And

Polymer/montmorillonite nanocomposites have received extensive attention of the academia and industry world, due to their excellent performance and potential application value. The two important factors of influence on performance of polymer/montmorillonite composites are the dispersed phase dimension and phase interface compatibility. The preparation of polymer/montmorillonite composites usually existed the bad dispersion and uneven distribution of montmorillonite layers, and the problem of poor interface compatibility of montmorillonite layers with polymer matrix, especially for weak polar or non-polar polymers, these problems are more common. In this paper, the montmorillonite layers were uneven dispersion and the problem of poor interface compatibility of montmorillonite layers with polymer matrix in the weak polar and nonpolar polymer matrix. With supercritical carbon dioxide as medium, the effect factors of morphology of montmorillonite particles on the supercritical conditions, the effect molecular chain of weak polar and nonpolar polymer on the intercalated behavior of montmorillonite and structure and properties of composites material were studied.After refinement and graft pretreatment of the original montmorillonite, the morphology of montmorillonite particles were characterized by fourier infrared spectrum (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) analysis and static contact angle test. The results show that the surface grafting has successfully improved the hydrophilic of montmorillonite, and increased dispersible layers of montmorillonite particles. On this basis, the montmorillonite was intercalating modified by using quaternary phosphonium salt. The influence of intercalating medium, dosage, phase state, and structure of intercalating agent on structure and properties of montmorillonite was investigated. The results show that the preparation of organic montmorillonite in supercritical carbon dioxide has a bigger basal spacing and more dispersible layers than montmorillonite treated in the solution, and can be directly added to the preparation of polymer composites without post-processing. The results also show that montmorillonite modified with silane and quaternary phosphonium salts had a higher basal spacing and more dispersal layers than montmorillonite only modified with quaternary phosphonium salts. Further the study of the intercalating agent dosage, phase state and the structure of the quaternary phosphonium salt, the results show that too little intercalating agent make the cation exchange of montmorillonite interlayer is not sufficient, whereas too much intercalating agent make montmorillonite particles be packaged by intercalating agent, which is not conducive to molecular of intercalating agent which inserted montmorillonite interlayer for ion exchange. When the intercalating agent content is 0.6 times the montmorillonite cation exchange capacity (CEC) and tetradecyltrihexylphosphonium chloride (TDTHP), which has good flexibility of long alkyl side chain and is liquid at room temperature, the largest layer spacing of preparation of montmorillonite is 2.32 nm, increasing 1.09 run compared to refinement montmorillonite, and the layer of dispersible tablets is the most.The PBS/montmorillonite composites which the organo-montmorillonite was introduced into weak polar poly (butylenes succinate) (PBS) were prepared by means of melt-compounding method. XRD and TEM analysis results show that the organo-montmorillonite modified using TDTHP quaternary phosphonium salts loadings of 0.6 times the montmorillonite (GMMTb-TDTHP (0.6 CEC)) with big basal spacing and more dispersed structures was relatively uniform dispersion in PBS and preferable interface compatibility with PBS matrix. Introduction ethylene-acrylic acid copolymers (EAA) into PBS/GMMTb-TDTHP blends, it was found that composites with EAA had much uniform dispersion of organo-montmorillonite in PBS matrix, and better interface compatibility between montmorillonite and PBS compared with that of composites without EAA. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile tests, notched Izod impact tests and flexural tests results show that the composites had more uniform dispersion of organo-montmorillonite in PBS matrix, and better interface compatibility between montmorillonite and PBS, and had more excellent combination properties. On this basis, the content of GMMTb-TDTHP in blends was changed. It was found that too little or too much organo-montmorillonite content had a bad effect on improving properties of composites, and the excellent overall properties of the composites were obtained, when the organo-montmorillonite content was 5 wt%.The PP/GMMTb-TDTHP composites which the GMMTb-TDTHP was introduced into nonpolar polypropylene (PP) were prepared by means of melt-compounding method. The XRD and TEM analysis results show that the organo-montmorillonite layers had a poor dispersion in PP matrix. The introduction of EAA into PP/GMMTb-TDTHP blends improved dispersion of the organo-montmorillonite layers in PP matrix. Further, maleic anhybride grafted polypropylene (PP-g-MAH) was introduced into PP/EAA/GMMTb-TDTHP blends. It was found that montmorillonite layers exhibited relatively uniform dispersion in polymer matrix and good interface compatibility with matrix. DSC, DMA and mechanical properties results show that the properties of composites had improved except of notched Izod impact strength when PP-g-MA was introduced into the composites. On this basis, the content of GMMTb-TDTHP (0.6 CEC) in blends was changed. It was found that the properties of the composites gradually increased with increasing GMMTb-TDTHP (0.6 CEC) content, with the exception of a gradually decrease in notched Izod impact strength.Finally, PBS and PP matrix composites were prepared by changing length-diameter (L/D) ratio of twin-screw extruder, respectively. The results show that organo montmorillonite in PBS composite treated in small L/D ratio of twin-screw extruder had a relatively uniform dispersion, and the properties of the composite were relatively excellent due to high melt index and good fluidity of PBS. However, organo montmorillonite in PP composite treated in big L/D ratio of twin-screw extruder had a relatively uniform dispersion and the properties of the composite were relatively excellent due to low melt index and poor fluidity of PP.