超高速射出成型流變行為研究

Study on Rheological Behavior of Ultra High Speed Injection Molding

陳品宏(Pin-Hong Chen)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000479

摘要

本研究主要探討在超高速射出成型時對於熔膠流動上黏度變化的影響，使用PS塑料在模厚2 mm之狹長矩形截面流道中，並保持塑料與模具分別在200、215、230 oC相等的溫度狀態與最大射壓之製程條件下，改變射出速度範圍由100至1500 mm/s，透過感測器求得壓力降與流率，並經由狹縫流黏度公式計算實驗黏度曲線，並針對黏滯熱與邊界滑動造成的影響進一步修正。最後，對實驗結果所發現的第二牛頓區以自由體積理論作進一步地分析與探討。
由實驗結果顯示：黏滯熱與邊界滑動所影響的比例隨著射出速度增加而上升，隨著模具與塑料溫度的增加而下降。在射出速度1000 mm/s後，剪應變率達到150000~200000(1/s)之間，材料黏度曲線有開始趨於平緩的現象，達到第二牛頓區。並以自由體積理論推測在超高速射出成型下，高射壓對剪應力的影響與高射速對剪應變率的影響達到一個平衡的狀態，造成第二牛頓區。而對於不同材料其分子量、分子結構、密度等分子特性將會影響高分子對壓力的敏感度與第二牛頓區的範圍。

關鍵字

自由體積理論 ； 黏滯熱 ； 邊界滑動 ； 第二牛頓區

並列摘要

This study focus on melt flow toward to the viscosity under ultra high speed injection molding. This experiment use the Polystyrene resin in 2 mm thickness with narrow rectangular section and keep mold and melt at the same temperature equal to 200, 215 and 230 oC with the maximum injection pressure condition. The experiment method will change the injection speed from 100 to 1500 mm/s and obtained the pressure drop and flow rate through sensors. The experimental results will be calculated with slit flow model and corrected for the effect of the viscous dissipation and wall slip by comparing with the ideal viscosity curve. Finally, the reason of the second Newton area will be conjectured by the free volume theory.

The experimental results show that the effect ratio of viscous dissipation and the wall slip increases with the increase of injection speed and decreases with the increase of mold and melt temperature. When the injection speed is over 1000 mm/s, the shear strain rate is between 150000 and 200000 s-1. The material viscosity curve become constant and reached the second Newton area. By the free volume theory conjecture which under the ultra high speed injection molding, the high injection pressure with the shear stress and high injection speed with the shear strain rate reach into balanced state and result in the second Newton area. For different molecular weight, molecular structure, density and other polymer molecular characteristics of materials will affect the pressure sensitivity and the range of the second Newton area.

並列關鍵字

the free volume theory ； the second Newton Area ； wall slip ； viscous dissipation

參考文獻

6. 陳嘉濠，“高分子熔膠微流道流變特性之研究”，中原大學碩士論文(2003)。

7. 黃建彰，“聚苯乙烯熔膠微流道流變特性之研究”，中原大學碩士論文(2004)。

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