Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2603
標題: EVA/LDPE混合塑料與純LDPE塑料之薄件射出成型品之機械性能
Mechanical Properties of Injection Molded Thin-Wall LDPE and EVA/LDPE Parts
作者: 梁凱勝
Liang, Kai-Sheng
關鍵字: ultimate stress
極限拉伸應力
ultimate strain
LDPE
EVA
crystallinity
injection molding
極限應變
LDPE
EVA
結晶度
射出成型
出版社: 機械工程學系
摘要: 本文探討一個射出成型薄件之機械性質,主要針對純LDPE塑料及EVA/LDPE混料之射出成型作研究。此研究首先探討入口熔膠溫度、模溫、保壓壓力對純LDPE射出成型品結晶度和機械性質之影響,經由拉伸測試取得模流方向之極限拉伸應力、極限應變及楊氏係數。並引用之前黃文彬論文所得之結晶度結果,其論文發現當入口熔膠溫度在165℃-185℃時,結晶度會有一個最小值,而這個最小結晶度相對應之最小極限拉伸應力也出現在此研究所獲得之結果;此研究發現在模溫為33℃-50℃之溫度範圍內,極限拉伸應力也會出現一個最小值,但卻沒有出現一個相對應之結晶度低點;此研究亦發現楊氏係數會隨著表面層的厚度增加而變大。除了對純LDPE塑料成型品進行研究外,本文並探討EVA含量對EVA/LDPE混合塑料射出成型品縱橫向之極限拉伸應力和極限應變之影響,結果發現添加EVA會使LDPE成型品之極限應變性能大幅提昇,但研究結果亦發現融合線之出現會使成型品的機械性質大幅下降。
This work investigates the mechanical properties of an injection molded part. The considered materials for injection molding were a LDPE polymer and a LDPE/EVA copolymer. For the LDPE injection molded part, the effects of inlet melt temperature, packing pressure and mold temperature on its crystallinity and mechanical properties were investigated. The machine-direction tensile ultimate stress, strain and Young's modulus were obtained. The degree of crystallinity was obtained from a previous work performed by Huang. In Huang's work, a minimum crystallinity was found for the inlet melt temperature in the range 165℃-185℃. This minimum crystallinity appears to directly affect the tensile ultimate stress and strain. A minimum tensile ultimate stress was found for the mold temperature in the range 33oC-50oC, but there is no corresponding minimum crystallinity appearing in the result. The Young's modulus tends to increase with the skin layer thickness. For the LDPE/EVA injection molded part, the effect of EVA content on the tensile ultimate stress and strain both in the machine direction and perpendicular to the machine direction were investigated. The result shows that adding EVA into LDPE significantly increases the tensile ultimate strain. It was found that the weld-line deteriorates the mechanical properties of the injection molded part.
URI: http://hdl.handle.net/11455/2603
Appears in Collections:機械工程學系所

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