PVC Gelation And On Foaming Process Influence Research

Because of its special multilayer particle morphology, the PVC resin so that itexperienced during processing more complex changes in particle morphology, but the PVCresin is not completely amorphous polymer, the presence of small amounts of its internalinitial microcrystalline structure the subsequent processing continues to melt, therebyforming a secondary crystallization. Molecule particle morphology and internal crystalstructure changes combined will the PVC melt rheological properties of viscoelastic andapplication performance of the products have a greater impact. Therefore, understanding ofPVC particles and crystallization characteristics of the changes in the process （i.e., thegelation process）, for guiding the performance of PVC processing and control products haveimportant significance.This article is mainly through the torque rheometer PVC dry blend mixing study thetemperature and speed of the PVC gel degree, determine the shear sensitive characteristics ofPVC. Research torque rheometer curve torque minimum point to the maximum torque pointof gelation increases process, and the relationship between the analysis of torque, theprocessing temperature, the degree of gelation three and using different rotational rheometercondensate viscoelastic behavior of plastic PVC system. Intermittent foaming, studies lastspecimen of supercritical CO₂foaming pressure and foaming temperature, as well as thedegree of gelation of the foaming process. Finally, DSC measurements of the sample after thefoam, PVC gelation degree in supercritical CO₂.The results show that: PVC degree of gelation increases as the processing temperatureincreases, increases as the rotor speed increases, and the speed and the shearing action of theimpact of PVC gelation process is more apparent. Torque rheogram torque lowest point to thehighest point of the torque between the degree of PVC gelled with the extension of the curveis increased, and exhibits a parabolic growth trend. Torque, the processing temperature aswell as the degree of gelation three mutually are increased proportional relationship, andsatisfies the polynomial fitting herein. The rotational rheometer test characterization of thePVC samples dynamic storage modulus G ’and the dynamic loss modulus G’’, indicating that the material system shows a high flexibility, and with the increase in the extent of gelation,the sample G ’and G’’ are increased, indicating that the increase in the viscoelasticity of thesystem as a whole. By changing the foaming pressure and foaming temperature of thesupercritical CO₂foamed, indicating that the PVC foam samples of the cell diameterdecreases, the cell density increases with the increase of the degree of gelation. Under thesame foaming process, with the increase of the foaming pressure, the cell diameter is reduced,the cell density is increased with the rise of the foaming temperature, a foam diameterincreases, the cell density decreases.