| Summary: | 碩士 === 清雲科技大學 === 機械工程研究所 === 94 === This study investigated the effect of the process parameters on the mechanical properties of PP/wood-fiber composites (30% and 50% wt.) by microcellular injection molding process. Nitrogen was used as the blowing agent. Process parameters like injection speed, melt temperature, shot size, microcellular processing pressure (MPP), and supercritical fluid (SCF) level were changed to investigate the effects on the mechanical property. DSC and TGA were used to study the thermal property of the solid/foamed sample. Finally, Taguchi method was used to optimize the tensile strength of the PP with 30%wt. wood-fiber.
The results showed that as injection speed, MPP, shot size are increased, so is the tensile and flexural strength for PP with 30%wt. wood-fiber. However, as the melt temperature and SCF level are increased, tensile and flexural strength are decreased. For impact test, as SCF level and melt temperature are increased, toughness is increased as well. For thermal property, TGA value is not changed for solid/foamed sample. Moisture test showed that as wood-fiber content is increased moisture sorption rate is increased and foamed sample has higher sorption rate than that of solid sample. On Taguchi experiment, the sequence of most critical factor is SCF, melt temperature, shot size, and injection speed respectively.
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