Polymer Morphological Evolution In Melting Process And Dispersion Mixing Characteristics Under Volume Elongational Deformation

Polymer processing equipment and processing method have a close relationship withpolymer’s performance and morphological evolution from solid state to melt state. Unlikescrew extrusion, the morphological evolution has its own characteristics in volumeelongational deformation plasticizing transporting process invented by Professor Qu, whichinfluencing the dispersion and mixing effect and determining the performance of extrusionproducts. Therefore, the research on polymer morphological evolution in melting process anddispersion and mixing characteristics have important value and significance. It is significantto deepen the understanding of polymer material plasticizing conveying method under volumeelongational deformation, and it laid the foundation to further improve mechanism and modelon the process of plasticizing and conveying polymer.The morphological evolution was systematically analyzed under volume elongationaldeformation from the perspective of single component polymer and two componentimmiscible blends. Through the cooling experiment we analyzed the morphological evolutionin melting process form several kinds of single component polymer, and further researchedthe influence of process parameters for HDPE morphological evolution. For two componentimmiscible blends, on the one hand, using cooling experiment we analyzed the blendmorphological evolution, on the other hand, we analyzed completely melt blend’smicromorphology change and dispersion and mixing characteristics. In addition, PA/TPO andPP/PA blends’ micromorphology were analyzed, and the size distribution of the dispersedphase was estimated; micromorphology, crystal structure, mechanical and thermal propertiesof PBS filled with CaSO₄and TiO₂nanoparticles were analyzed.It was shown that under volume elongational deformation polymer’s morphologicalevolution have four characteristics sequentially including multi melt film, honeycomb, moltenpool solid bed and suspension, promoting the dispersion and mixing characteristics for themulticomponent blend system. Under volume elongational deformation much plastic energydissipation, friction energy dissipation and viscous energy dissipation were produced bypolymer’s plastic deformation, melting and morphological evolution, and interface changesand evolution process, which are important heat resources for polymer’s morphologicalevolution. The rotation speed is important for polymer’s morphological evolution undervolume elongational deformation. And the characteristics of positive displacement conveying,short residence time, short melting time, high molten plasticizing efficiency, short thermalmechanical process were shown in the volume elongational deformation plasticizing extruder. It was found that the volume elongational deformation plasticizing and conveyingprocess has good dispersion and mixing effect for the immiscible blends from the study on thePA/TPO and PP/PA blends’ micromorphology. Dispersed phase was mainly presented in theform of droplets. Dispersed phase in the form of droplets was easily broken and evenlydistributed under volume elongational deformation of the cavity volume in the plasticizingand conveying unit. Volume elongational deformation plasticizing extruder has gooddispersion and mixing effect on the immiscible blends with large viscosity ratio, and littledependence on the viscosity of material. The droplet size of the dispersed phase is smaller andthe dispersion and mixing effect is better with the matrix of high viscosity and the dispersedphase of low viscosity.It was shown that the volume elongational deformation plasticizing and conveyingprocess has good dispersion and mixing effect for PBS filled with nanoparticles from theanalysis and test of CaSO₄/PBS and TiO₂/PBS. The nanoparticles acted as rigid filler toenhance the mechanical properties and thermal barrier to promote the thermal stability.