本研究使用光強法量測在高剪切率下﹐液晶高分子PHIC之低濃度溶液如何 由等方向性的液體轉換為不等方向性的液晶型態。所使用的光強法可以測 得在穩態流動的狀態下之液晶溶液的雙折射隨剪應力的變化﹐同時亦可測 得雙折射的軸向﹐而藉此了解在流動時分子的排列方向。在不同的剪切率 下量測光學性質﹐同時也測量應力﹔並與光學觀察的結果相互參照﹐以了 解流體型態與剪應力之間的關係。同時﹐實驗也對應力鬆弛的現象加以討 論。由實驗結果顯示﹐在相同濃度下﹐雙折射率確實會隨著剪切率的增加 而增加﹐且軸向也會逐漸平行於流動方向﹐此現象在濃度高時更為顯著。 於25%?20%?15%的濃度下﹐剪應力約正比於雙折射率的1.32次方﹔但 在10%的濃度下﹐剪應力正比於雙折射率的1.16次方﹐顯示10%時﹐PHIC液 晶高分子溶液的行為較接近於一般具柔軟分子鍊的高分子流體。而在高濃 度下﹐較容易形成流動雙折射﹐但剪切力對其影響較小。 Our research adopts the method of transmitted light intensity measurement to investigate the behavior of liquid crystalline polymer solution of PHIC.The study focus on the transformation oof the isotropic solution into an anisotropic solution under high shear rate.The optical technique provides simultaeous measurement of birefrigence and its axes,so that the oritation of molecular under flow can be obtained.The stress can be also measured to reflect its relation with the optical results.At the same time,we also make some disscusions of stress relaxation. The results shows that birefrigence is really increase with shear rate under the same concentration,and the axes also paralle to flow dircetion. This phenomenon is more clear as the concentration is high.We also found the shear stress is proportional to the birefrigence by the order of 1.32 at concentration,25%,20%,15%,but proportional to the birefrigence by the order of 1.16 at concentration ,10%.It shows that the flow behavior of PHIC liquid crystalline polymers(LCPs) is closer to the common flexible chain polymer ,and at higher concentrations, it's easy to form the flow birefrigence.At this time,shear rate does less effect to birefrigence.
