高分子共擠製過程之膜層界面觀察及速度量測

Observation of Interface Behavior and Measurement of Flow Velocity in the Polymer Co-Extrusion Process

廖唯傑(Wei-Chieh Liao)

指導教授 ： 陳仁浩

國立交通大學/工學院/機械工程系所/碩士(2016年)

摘要

高分子多層膜已大量應用於日常生活中，如食品包裝、汽車或建築物窗隔熱膜等。常見高分子薄膜的複合技術－共擠製擁有生產連續與設備簡單的優點，而過去的研究指出界面間的滑動現象會對產品界面的穩定性造成影響。
　　本研究的目的為探討高分子聚合物在共擠製時，高分子／高分子的層間界面作用行為對界面不穩定現象的影響。進而提供提升共擠製產品良率的方向，以利塑膠工業之發展。
　　本研究選用兩組不同相溶性的材料組合，分別為PP/PS與PP/EVOH，規劃設計以不同擠出速度、疊層數共擠製產生多層結構，並在加工過程中注入金屬顆粒至共擠製流道內，再透過玻璃觀察窗觀察記錄流體界面間的表現並據以量測流體速度。
　　研究結果顯示在兩層共擠製與四層共擠製中PP/PS組比起PP/EVOH組更容易發生界面不穩定，不論是在熔融狀流體或是固化後試片皆能在PP/PS組的界面處觀察到波紋狀的結構。而在速度量測方面在界面處觀察到較大的速度震盪，並且在PP/EVOH組於低擠出速度時觀察到較大的層間速度差異，即在其界面處有較大的滑動現象發生。此量測方式有助於分析、理解流體的流動行為。
　　影響界面穩定度的原因乃界面處剪應力的分佈情形，若能適當消除剪應力之影響則能提升共擠製產品界面的穩定度。依本實驗觀察結果，一定程度上的界面滑動即能消除部分剪應力所導致之界面不穩定現象。爾後能在共擠製過程中添加助劑以利產品之界面滑動來提升界面間的穩定度。

關鍵字

共擠製 ； 塑膠 ； 流體可視化

並列摘要

The multilayer polymer films are highly applied in all areas, such as food packages, tinted windows films, etc. The co-extrusion is a common to produce multilayer polymer films and has the advantage like continuous productions and simple equipment. Previous researches indicate that slip phenomenon will affect the interface stability of products.
This research will investigate the effect of polymer/polymer interface’s interactions to the interface instability in co-extrusion processing. Provide the direction of increasing production yield and promote the plastic industry
This research chose two material’s groups with different intermiscibility , which are PP/PS and PP/EVOH. Designed the co-extrusion experiment with different extrusion velocity and layer numbers to produce multilayer structures. Meanwhile injected metal particles into the co-extrusion flow channel. Then observed appearances of interfaces in the polymer flow and measured the velocity of polymer flow through the Observation window.
The results indicate that PP/PS group is easier to emerge interface instability in two layers’ and four layers’ co-extrusion process. We can found the flexural structures from the melt polymer flow and solidifying specimens. In terms of flow velocity measurement, we found the flow velocity largely fluctuate near the interfaces and larger velocity difference between a PP layer and a EVOH layer at low extrusion speed. That is greater slip phenomenon happen at the interface. This method of measurement is helpful in analyzing and understanding flow behavior of fluids.
The reason that affect interface stability is the distribution of shear stress at interfaces. If appropriately eliminate the shear stress, then can improve the interface stability of the co-extruded product. Under these experimental observations, a certain degree of interface slide is able to eliminate part of interface instability that caused by shear stress. Maybe additives can be added in the co-extrusion process to facilitate the interface slide phenomenon of products to enhance the interface stability.

並列關鍵字

co-extrusion ； polymer ； flow visualization

參考文獻

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