Effects Of Injection-Molded Processing Parameters On Polypropylene Microcellular Foaming Material

The microcellular foam material, which has saving cost, enhanced properties, and otheradvantages, has been widely used in many fields. In this study, we use the polypropylene(PP)and supercritical CO2as the matrix and the physical blowing agent to prepare PPmicrocellular foam material. We have characterized the microstructure, and adjusted theinjection-molded processing parameters to study the effects on the mechanical properties ofmicrocellular foam.In the first, this study has summarized and compared a variety of processing technologyof cellular foaming. Considering the industrial applications, we choose the injection-moldedmethod to prepare the foaming materials. In the second, we have introduced the theories andphysical models of bubble nucleation, growth and stability, which can provide the basedanalysis of forming microstructure of the PP foaming material. Finally, we choose fourprocessing parameters (injection temperature, injection pressure, the SCF injection volumeand injection rate) as the variable quantities to molding the materials, and then characteringthe microstructure and testing the performance.During the experiment, we have designed a set of orthogonal test, and prepared PPfoaming materials which has four different molding parameters in the forming process.Through the comparing of comprehensive properties, we obtain the optimum parameters,which providing the research foundation of continue study, and ensuring the rationality ofparameters’ choosing. And then, we choose five variables in each processing parameter asthe contrast experiment, and obtained the influence of different processing parameters on themicrostructure and mechanical properties of the foaming materials. At last, combined withthe foaming theories, we analysis the causes of the results from the mechanism level.This study has provided a theoretical basis for preparation of PP foaming materialswhich have high quality structure and excellent performance, and supplied a technical basisfor industrial production.