RHEOLOGY OF GAS-CONTAINING POLYMER SYSTEMS

The paper contains a review with original theoretical and experimental data on the basis of the rheological behavior of gas-containing systems - thermoplastic melts - during extrusion. The more important physical aspects of the flow of gas -containing systems are analyzed for a uniphase and a biphase flow. Equations are developed for a qualitative description of these systems. The usefulness of the proposed relationships in the engineering design of moulding equipment has been experimentally verified. A comparison is made of the pressure-volumetric flow rate characteristics with the structure of the flow and of the obtained extrudates. Recommendations are made for calculating the boundaries of optimized flow conditions of gas-containing thermoplastic melts. These recommendations should ensure the obtaining of extrudates with a uniform fine-cellular structure and having excellent operational characteristics. A good agreement has been obtained for experimental and theoretical results.