5.1 結論
本研究藉由有限元素法模擬三維共擠出成型過程，包括等溫與非等溫
之檢討，獲得匯合區域之高分子融體流動行為，如匯合區域的速度場、剪 切率、溫度場與剪應力等。研究中使用材料為非結晶型塑料PC與 PMMA， 配合剪切黏度實驗數據所選用流變模型為Modified Cross Law，用於一般需 描述低剪切速率的剪稀薄效應黏度行為，至於成型參數包括討論匯合角
5. 當支流與主流路黏度比變大時，由於在等溫系時只需考慮到剪稀薄效 應，因此包覆現象會比非等溫共擠出時嚴重；而在非等溫系統時，由於 高分子塑料流動時因剪切作用會導致溫度上升，進而影響到黏度的變 化，且支流路由於黏度較大使得溫度上升亦較多，而導致黏度下降幅度 比主流路多，其黏度比會下降使包覆程度變不明顯。
5.2 未來展望
1. 由於高分子流體為黏彈性流體，在先前文獻中指出，非線性黏彈性流體 其第二正向應力差在擠出過程中會產生二次流，此二次流為垂直擠出方 向的流場，會造成擠出過程中界面的重新排列，為影響界面包覆形狀的 主要因素。若未來能進行黏彈性模形模擬，並與純黏性模型比較其差異 性，並藉由實驗來探討二次流動是否為影響包覆現象主要因素。
2. 網格質量(Quality)應更加均勻，以得到精確模擬結果，但網格質量均勻
化會導致網格數大量增加，使計算繁複耗時，須從硬體方面著手。
3. 從模擬結果得知，當黏度差異過大，單純從匯合角度、流速與薄膜厚度 無法有效改善包覆現象。在之後能針對材料性質做改善，使其剪切黏度 差異不致過大，從而改善包覆情形。
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