本研究中以聚乙二醇(PEG200)與二氧化矽製備出剪切增稠複合流體，並利用流變儀來量測其剪切增稠的特性，我們嘗試找出具有最佳剪切增稠效果的條件，並希望可以進一步應用於防護器材上。

首先，我們發現隨著二氧化矽的體積分率增加，剪切增稠現象會從連續性剪切增稠(CST)漸變為不連續性剪切增稠(DST)，而不連續剪切增稠(DST)的黏度曲線斜率在接近臨界體積分率處呈現發散，顯示系統接近堵塞(Jammed)狀態，此不連續性剪切增稠現象的急遽黏度變化較適合應用於防護方面。此外，我們也發現在剪切增稠的過程伴隨著法向應力差的產生，歸因於具各向異性的hydrocluster所導致。

接著我們改變外在環境溫度，觀察到溫度的上升使剪切增稠現象減弱，因此需要較大的臨界剪切速率才能誘發剪切增稠現象；但臨界剪切應力卻不隨溫度而改變，最後經連續相黏度規格化後得知剪切增稠效果的減弱大部分來自於連續相受溫度的影響。

為了更進一步了解剪切增稠現象，我們利用大震幅震盪剪切(LAOS)探討剪切增稠過程的非線性黏彈行為。我們得知不連續性剪切增稠現象中的非線性彈性部分是由應變速率主導的strain-stiffening現象；非線性黏性部分由應變速率主導的shear-thickening現象，但隨著角頻率的增加非線性黏性會轉變為應變所主導。

最後經由積分Lissajous-Bowditch curve中的應力-應變曲線面積可以得到剪切增稠時所耗散的能量，確認剪切增稠行為的發生伴隨著能量耗散增加，且DST的能量耗散效率比CST佳，並隨著角頻率增加能量耗散的效果更為顯著。此結果顯示我們所配製的剪切增稠複合流體在剪切增稠現象發生時具有黏度(硬度)上升與能量耗散的效果，為同時兼顧剛性與阻尼性的複合材料。

The main aim of this present dissertation is to prepare effective condition and formulation of the shear thickening fluid of the SiO2 blended with polyethylene glycol (200) was performed through the rheometer by measured shear thickening phenomenon with various concentrations. The shear thickening effect was optimized to find out the best conditions for usage as the protective equipment.

Upon increase the volume fraction of SiO2, the viscosity was increased continuously (CST) to discontinuously (DST). The slope of viscosity curve in shear thickening part was found as increased with increased volume fraction (Φ) and diverged at critical volume fraction(Φ_c). Such a diverging viscosity is mainly related to jamming phenomenon. Also, we have found the normal force emerges while rheological measurement, which is attributed to the formation of particle’s anisotropic microstructure (hydrocluster).

In addition, influence of external temperature was studied to understand shear thickening behaviors upon the increase the temperature. The reduction of the shear thickening effect was observed while increased temperature of SiO2 blend. Thus, we have used the viscosity of PEG200 to normalize the temperature effect, and found that the main reason for shear thickening effect reduction due to the continuous phase of PEG200, which was influenced by temperature.

In order to understand further shear thickening phenomenon, we have used large amplitude oscillatory shear (LAOS) to investigate the nonlinear viscoelastic behavior of shear thickening phenomenon. The obtained results indicated the elastic nonlinearity and viscous nonlinearity were donated by strain-rate. However while increased the angular frequency, viscous nonlinearity have been converted to strain dominated. Finally, we have obtained the dissipated energy by integrating the area of Lissajous-Bowditch curve, which shows an obvious increase in energy dissipation in the shear thickening region. The dissipated energy of DST is more efficient than dissipated energy of CST, and an increase of angular frequency tends to enhance the dissipated energy. These results imply that obtained shear thickening fluid composite can raise viscosity (hardness) and energy dissipation as shear thickening occurs.

The above comparison results revealed that presented optimized condition may possible to produce fluid analogue to usage as the protective equipment.

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