| dc.description.abstract | In this study, the semi-crystalline material polypropylene and the amorphous material polystyrene were used as the substrate. The exothermic foaming agent (azodicarbonamide) was added to the substrate to make samples used in injection molding experiments. After experiments done, using Moldex3D mold flow analysis software verified flow-length results gotten from short shot experiments. In our experiments, we used one-factor one-time experimental design to carry out for the three-factor level of five parameters such as: injection speed, shot size, melt temperature, mold temperature and amount of CBA. Therefore, the effect factor analysis was used to choose the significant factors for the Taguchi experimental design. Finally, regression analysis method and S/N analysis method were used to analyze the trend of parameters and then compare each ways’ pros and cons.
We observe the experimental results from macroscopic phenomena such as: weight, specific weight, and expansion ratio to find better foaming efficiency, and microscopic phenomena such as: electron microscopy (SEM) to calculate bubble density and size. Taking great consideration of the optimal parameters and setting these parameters to redo experiment, finally compare two materials in expansion ratio. The results show that the semi-crystalline material is less likely to foam due to the crystallization
phenomenon. PP has the best expansion ratio at low rate of injection speed, high melt temperature and low mold temperature, while PS is high rate of injection speed, medium melt temperature, and low mold temperature have the best expansion ratio.
For this experiment, the trend of the parameters obtained by the one-factor one-time experimental design and the Taguchi experimental design is the same, and the experiment and time cost obtained by the experimental design are lower. Therefore, the one-factor one-time experimental design for the injection experiment is better for experimental design. The results are the same as that obtained by the regression analysis method and S/N analysis method, so it is concluded that the parameter trend can be quickly and easily obtained by using the S/N analysis method.
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