Study On Dissolved Quantity And Dissolution Rate Of Supercritical CO₂ In Polystyrene

The supercritical fluid foaming continuous extrusion process is the currently main way of industrial production of microporous plastics at present.The most commonly used foaming agent is supercritical CO₂.The key step in the continuous extrusion process of supercritical CO₂ foaming is the formation of supercritical CO₂/polymer homogeneous system,which seriously restricts the subsequent forming process.In order to form homogeneous supercritical CO₂ polymer phase in as short a time as possible,two problems need to be solved:one is to determine the flow rate of supercritical CO₂ reasonably based on the accurate calculation of the dissolved quantity of supercritical CO₂ in polymer;the other is to achieve as much supercritical CO₂ dissolution as possible in a given process time by increasing the dissolution rate of CO₂.This paper takes PS as the research object to study the dissolution amount and dissolution rate of supercritical CO₂ in polymer under static condition and mixed element respectively.The main research results include:（1）A device for measuring the dissolved quantity and dissolution rate of supercritical CO₂ in polymers was built.The dissolved quantity,solubility and dissolution rate of supercritical CO₂ in PS were measured in the range of temperature170¹90℃and pressure 7.5⁹.5MPa.The effects of different temperatures and pressures on the dissolved quantity,solubility and dissolution rate were analyzed.（2）The solubility,solubility and dissolution rate of supercritical CO₂ in PS under static conditions were simulated.The accuracy of the simulation method was determined by comparing the simulation results with the experimental results.（3）The dissolution rate of supercritical CO₂ in PS under shear condition was simulated,and the effects of temperature,pressure and shear rate on the dissolution rate were analyzed.