Development Of Micro-nano Layer-stacking Equipment And Syudy On Structure-property Relationships Of Polypropylene/Carbon Nanotube Composites

Microlayer co-extrusion technology is an emerging technology in polymer processing field, and it can be used to prepare microlayer polymer materials which have excellent mechanical property,photoelectric property and other properties. The progress of this technology is significant to the development of high-performance,multi-functional and low-cost polymer materials.In this study, the progress of microlayer co-extrusion technology was reviewed, and the principle bottleneck and technical problems of microlayer co-extrusion technology were analyzed and revealed. Then,the torsional layer-stacking extrusion technology was proposed, and the micro-nano layer-stacking extrusion equipment based on it was developed. Finally , polypropylene (PP) microlayer material and PP/multiwalled carbon nanotube (MWNT) microlayer composites were prepared by micro-nano layer-stacking extrusion equipment, and structure and properties of polymer materials were investigated. The main work is as follows:1. A novel microlayer co-extrusion technology named torsional layer-stacking extrusion technology was proposed based on the principle of melt differential and integral, and a micro-nano layer-stacking extrusion equipment was developed based on the above technology. The runner structure of layer-stacking element possesses some notable characteristics such as adjustable layered number and variable structure,which overcome the drawbacks of the existing flow multiplier unit.2. The flow field analysis of layer-stacking element runner was carried out by Moldex3D, the flow condition, distribution of shear stress,and fiber orientation in layer-stacking element runner was investigated.The flow characteristics and laws of materials in layer-stacking element runner were obtained.3. PP materials with different layer numbers were prepared by the micro-nano layer-stacking extrusion equipment, and the effect of microlayer shear force on the crystallization behavior and tensile properties of PP was investigated.4. PP/MWNT composites with different layer numbers were prepared by the micro-nano layer-stacking extrusion equipment. The effect of micro-layer shear flow field on the dispersion and orientation of MWNT in the polymer matrix was investigated, and the influences of the dispersion and orientation of MWNT on mechanical property, electrical conductivity, crystallization behavior and thermostability of composites were also analyzed. The method of dispersion and orientation along the flow plane of MWNT controlled by microlayer shear flow field was provided and the relationship between dispersion and orientation of MWNT in micro-layer shear flow field and properties of composites was built.5. Dispersion mechanisms and orientation mechanisms of MWNT in microlayer shear flow field were investigated. The morphological formation, development and evolution of the MWNT in microlayer shear flow field were revealed and the relationship between processing conditions and the dispersion and orientation of MWNT was built.In conclusion, this study proposed torsional layer-stacking extrusion technology, developed a micro-nano layer-stacking extrusion equipment and applied it to the research on the preparation and properties of polymer materials. The research on new technology, new equipment and application may provide new ideas and methods for the development of polymer processing equipment and technology as well as the solutions of relevant scientific problem in polymer materials field.