Injection molding of LDPE/BaSO4 blends - Mold filling studies

The injection mold filling behavior of a blend of low density polyethylene (LDPE) and barium sulphate (BaSO4) was studied experimentally and compared with that of pure LDPE. The method of short shots was used to analyze the mold filling behavior. An experimental study using a full factorial design was implemented with the following factors: mold temperature, injection speed and injection time. Experimental results and computer simulation predictions of the mold filling stage were found to be in acceptable agreement. The produced short shots with the LDPE/BaSO4 blend have significantly lower percentages of volume filled than those of the corresponding short shots with the pure LDPE. The increase in the melt viscosity and density of the polymer resin with the addition of BaSO4 cannot be neglected when producing injection molded articles with LDPE/BaSO4 blends. To study the deviations between the experimental results and the computer simulation predictions, a factorial numerical study was completed. The results show that the simulation predictions ale significantly affected by the accuracy of the polymer material properties.