聚丙烯碳酸鈣填充高分子熔融體之降服行為及其搖變特性

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Title:	聚丙烯碳酸鈣填充高分子熔融體之降服行為及其搖變特性
Other Titles:	Shear Yield and Thixotropic Behavior of Calcium Carbonate Filled Polypropylene Melts
Authors:	游明建 Yu, Ming-Jiann
Contributors:	王曄 Wang, Yeh 東海大學化學工程與材料工程學系
Keywords:	流變性質;降服行為;搖變性;碳酸鈣;聚丙烯;填充複合材料;應力鬆弛;熱塑性高分子 rheology;yield behavior;thixotropy;calcium carbonate;polypropylene;Filled composite polymer;stress relaxation;thermoplastic polymer
Date:	1999
Issue Date:	2011-06-15T02:44:05Z (UTC)
Abstract:	本研究係使用RDA II旋轉式流變儀，對熱塑性聚丙烯高分子填充碳酸鈣顆粒之熔融體，進行各種流變測試，其中包括穩態、動態及暫態流變測試。同時並檢測此類填充複材之降服及搖變行為，亦即與時間相關之流變性質。由穩態測試之流動曲線，在低剪速率區域可觀察到降服行為；並由動態測試之平原模數得到降服應力。另外，由觀察應力增長的應力超越現象，亦可得到降服應力；加上間斷剪速率測試，便能觀察到降服應力與停滯時間的關係。在進行搖變測試時，發現高濃度之填充複材有搖變行為；而應力鬆弛的殘存應力可發現高濃度之複材熔融體有降服行為。同時對影響測試之因素，如試片製備及其填裝、實驗參數以及儀器限制等，亦有深入之討論。此外本研究使用不同濃度之填充劑，並對填充劑表面處理對降服行為之影響加以分析。實驗結果顯示，在高濃度之填充材料才能產生降服行為與搖變特性；有表面處理之填充劑可降低填充複材之降服應力。 The present study used the rheometer of model RDA II from Rheometrics Scientific. In order to characterize the yield and thixotropic behavior of calcium carbonate filled polypropylene melts, i.e., the time-dependent properties. Various kinds of the rheological tests performed on the filled thermoplastic compounds. The study included steady shear tests, dynamic oscillatory shear tests, and transient tests. The steady shear tests provided the shear viscosity data from which the yield stress may be determined through extrapolation. On the other hand, a plateau can be clearly seen in storage modulus curve from small-strain oscillatory tests. A stress response with overshoot in a stress growth experiment may be observed for the yield behavior. The sequential step rate test provided the stress buildup as a function of rest time for filled melts. The thixotropic tests were performed too, from which characteristic hysteresis loop could be obtained. In the stress relaxation test, the stress remaining in the melt varied monotonically with time and finally tended to the constant residual stress was interpreted as the yield stress. The effects of the filler concentration and the surface treatment on the yield behavior were also studied.
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