| Summary: | 碩士 === 國立臺北科技大學 === 製造科技研究所 === 98 === This study is to analyze the tensile and impact properties of Nylon 66 (PA66). Specimens including 1, 2, and 3 mm of three types thickness and 20%, 30% and 50% of three types glass fiber (GF) content prepared by injection molding technique with a single gate (non-existing weld line) and a dual gates (existing weld line). Moreover, the breaking cross sections of tensile and impact specimen observed by using scanning electron microscope (SEM) to verify the flow orientation of glass fiber.
Results show both the tensile strength and impact value of the specimens existing weld lines are lower than those of non-existing weld lines. Because the weld line formed at the intersection of the two melt front, the cross section of the specimen observation by SEM indicates a breakaway type in existing weld line specimen, and a tensile-break type in non-existing weld line one. Results also show the larger the specimen thickness, the higher the tensile strength will be.
This is due to the smaller flow resistance in larger thickness specimen that caused a better filling effect. Young’s Modulus increases with the containing glass fiber increasing in non-existing weld line specimen. However, in existing weld line specimen, Young’s Modulus decreases when the fiber glass content is above 30%. Furthermore, if the sample is a non-existing weld line type, the more of the glass fiber content is, the higher the tensile strength. However, the tensile strength also decreases in existing weld line sample when the sample contains fiber glass above 30% GF, i.e. the weld line factor decrease. For the impact test, the impact values increase with the glass fiber increasing whether the specimen contains weld line or not.
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