Research On The Processing Conditions And Equipments Of Microcellular Injection Molding For Medical Products

Recently the polymer materials were widely used in medical products, the dimensional stabilities of medical products was highly concerned. The dimensional stabilities were the key point that restricted the polymer materials application in medical products. The microcellular injection molding technology could obviously improve the dimensional stabilities; however, for composite materials especially the glass fiber reinforced materials, the dimensional stability of the products should be further enhanced. This paper investigated the effects of processing conditions on the dimensional stabilities of medical products, using microcellular injection molding. Within the processing range studied, the optimized processing parameters were achieved.Based on the principle of microcellular injection molding, a new microcellular injection molding plasticizing system and a novel screw were developed for the microcellular injection molding technology, the screw was proved excellent dispersive and mixing capability. The relationship between the processing parameters and the cell morphology were investigated by the Moldflow numerical simulation software, the results showed that the influence of various process parameters in decreasing order were:melt temperature, gas content, the amount of injection, mold temperature and injection time. Still the relationship between the processing conditions and the dimensional stabilities of the molded polypropylene and glass fiber reinforced polypropylene specimens both in X direction and Y direction were performed, and proposed the optimized processing conditions for different content of glass fiber reinforced polypropylene. The effect of the cell microstructure on the dimensional stabilities and the mechanical properties were examined using the scanning electron microscope (SEM) to study the variation of cell size and density with different processing conditions. The results showed that the microstructure of cells affected the dimensional stabilities and the mechanical properties significantly, and it can be obviously improved with the optimized processing conditions especially for the medical products.