- 期刊
The Rabinowitsch Correction on Viscosity of Polypropylene/Supercritical CO2 Mixture at High Shear Rates
高剪率下聚丙烯／超臨界二氧化碳混合熔體黏度之Rabinowitsch修正探討
摘要
本文採用Rabinowitsch方法修正高剪率下聚丙烯／超臨界二氧化碳混合熔體之非牛頓特性，而探討其視黏度與真實黏度之差異性。結果顯示，以Cross-Eyring模式可適當描述PP與PP/CO2系統之真實黏度分佈，而修正前後之差異值則與剪率、溫度及CO2成份均相關。在低剪率下此差異值甚小，但會隨剪率升高而增加；當剪率高於一特定臨界值後，則差異値再度減少。差異值分佈呈現一鐘形曲線型態，並隨溫度升高與添加CO2而移向較高剪率區。最大偏差值發生在黏度曲線之非線性過渡區末端，其值約為16%，這顯示在處理高分子真實黏度數據時，Rabinowitsch修正仍為相當重要的一個程序。
關鍵字
無資料並列摘要
The Rabinowitsch correction is adapted to rectify the Non-Newtonian behavior for PP and PP/CO2 melts at high shear rates. The deviations between true viscosity and apparent viscosity are presented. The result reveals that the deviation is highly dependent on shear rate, temperature and CO2 content. Although minor at low shear rates, the deviation rises with increasing shear rates, whereas it diminishes as the shear rates rise beyond a critical value. The deviation profile exhibits a dome-shape distribution and moves toward higher sheared region with increasing temperature and CO2 addition. Maximum deviation of as high as 16% occurs at the transition region of viscosity profiles, proposing the scale of possible discrepancy on true viscosity if the Rabinowitsch correction is ignored.