聚乙烯合膠之流動行為的探討

本專題計畫將二不同結構的聚乙烯混合形成合膠（Blend）來探討混摻比率（Blending ratio）對聚乙烯流動行為的影響。所使用的樣品分別為一傳統製程製造的低密度聚乙烯（LDPE）及以metallocene觸媒製造聚乙烯（mPE）；其中後者為不結晶的熱塑性彈性體。所採用之樣品中除了兩個純料外，合膠的混合比率分別為1:3、1:1及3:1三種，故有五種不同比例之受測樣品。流動行為之探討以Keyness Galaxy III毛細管流變儀行之。測試過程中使用了三種不同長度/直徑（UD）比之毛細管模頭（Die）：分別為16、20及30。毛細管模頭之直徑為1.0 mm。測試的溫度為200℃、220℃及240℃。結果顯示五不同樣品所測得之黏度隨著樣品中mPE的含量增加而上升；且不按合膠比率呈系統性分佈。此一現象可用Arrehenius方程式ŋ=A e^(E/RT)中的常數來合理化。此外，五種樣品的流動活化能在測試範圍內，除了LDPE較大外，其餘四種樣品的流動活化能在實驗誤差範圍內，可視為相同。這歸因於LDPE具有較廣泛之纏結所致。

關鍵字

混摻比率；流動行為；毛細管流變儀； Arrehenius方程式

並列摘要

Two different types of polyethylene were used to study the flow behavior of their blends. They were a traditional low density polyethylene (LDPE) and a metallocene polyethylene (mPE); the latter is a thermoplastic elastomer polyethylene and is non-crystallizable. Blends were prepared in three different ratios, 1:3, 1:1 and 3:1, respectively. Including two counterparts, five samples were used in this study. The flow behavior of the samples was examined via a Kayness Galaxy III capillary rheometer. Three different dies were used. AII have the same diameter, 1 mm, but difference in L/D (Iength/diameter) ratio. They were 16, 20, and 30. Flow behavior was also examined with three different temperature, 200°C, 220°C and 240°C, respectively. Results showed that the viscosities of the samples increase with mPE content. However, the flow curves of blends did not distribute systematically with respect to blending ratio. They tended to shift to the flow curve of mPE. Such a phenomenon was rationalized by structure parameter A in Arrenhius equation, η= A e^(E/RT). Results also showed the flow activation energy of LDPE larger than those of the rest samples, which were considered the same within the experimental error. This is attributed to a significant entanglement effect in the LPDE.

並列關鍵字

LDPE ； mPE ； Blending Ratio ； Flow Behavior ； Capillary rheometer ； Arrehenius equation

國際替代計量

聚乙烯合膠之流動行為的探討

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