聚苯乙烯熔膠微流道流變特性之研究

Study on the Rheological Behavior of PS Melt Flowing Through Micro-Channels

黃建彰(Chien-Chang Huang)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2004年)

https://doi.org/10.6840/cycu200400307

摘要

隨著塑膠高分子成型技術日益提升，而所生產的零件也隨著微機械技術發展有日趨微小且精密化，運用微射出成型所生產的微機電產品零件需求日益增加。而微射出成型中熔膠流過微小尺寸的特性缺乏研究，因此對製程的掌握更增加了不確定性。本論文乃係針對高分子熔膠微流道流動的流變性質進行研究。
本研究在微流道流變量測模具上，使用的微流道尺寸分別為0.15mm、0.2 mm、0.3 mm和0.5mm之正方形截面流道。由於實驗之微流道為正方形截面，所以分別使用capillary flow model與slit flow model作計算分析並導入修正因子，在與傳統流變儀量測值相比。研究發現黏滯熱對高分子熔膠有4%~12%黏度減少之比例；又因射出成型過程當中，高分子熔膠處在較高剪應變率約 (1/s)以上的流動狀態下，所產生的邊界滑動現象作出研究與探討，研究結果發現，當流道尺寸降低、熔膠溫度增加，邊界滑動的速度便會隨之增大，然而在同一尺寸流道及同一溫度下，邊界滑動速度隨著剪應變率增加有減少的趨勢。
對於實驗結果可說明當高分子熔膠流變行為進入微小的特徵結構時，必須對於這些現象作更深入的討論，並期望研究結果對於高分子模擬流動軟體的開發與微成型技術層次的推進將提供相當的助益。

關鍵字

微流道 ； 邊界滑動 ； 黏滯熱 ； 微射出成型

並列摘要

The micro-parts molded by micro injection molding become more and more popular in MEMS (Micro-Electro-Mechanical Systems) applications.
Determination of melt rheological behavior within micro structured geometry is very important for the accurate simulation modeling of micro molding. Yet investigation of micro melt rheology is difficult due to the lack of commercial equipment. In this study, melt viscosity measurement system for polymer melt flowing through micro channel was established using a micro channel mold operated at a mold temperature as high as the melt temperature. Form measured pressures and volumetric flow rate both capillary flow model and slit flow model were used for the calculation of viscosity utilizing Rabinowitsch and Walters corrections. It was found that the measured viscosity values in the test ranges are significantly lower than those obtained from traditional capillary rheometer no matter capillary flow model or slit model are used for analysis. As micro channel size decreases, the percentage reduction in viscosity also increases. However, in the injection molding process, the shear rate often overtakes (1/s) may occur the slip on the wall of the mold, as the velocity of melt flowing increases, the percentage reduction in wall slip velocity also increases, This indicates microscopic scale melt rheological behavior is different from that of macroscopic scale and that current simulation packages are not suitable for micro molding simulation without considering this difference.

並列關鍵字

micro-channels ； micro-injection molding ； wall slip ； viscous dissipation

參考文獻

8. 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).

1. C. Harris, M. S. Despa and K. W. Kelly, Design and Fabrication of a Cross Flow Micro Heat Exchanger, J. Microelectromech. Sys. , 9, 502 (2000).

3. R. W. Friedl, Injection Molding of Sub-μm Grating Optical Elements, J. Injection Molding Technol., 4, 78 (2000).

4. L. Yu, Y. J. Juang, K. W. Koelling and L. J. Lee, Thin Wall Injection Molding of Thermoplastic Microstructures, SPE Tech. Papers., 46 , 468 (2000).

9. Mooney M. “Explicit formulas for slip and fluidity“J.Rheol.2 210, (1931).