本論文是以流體力學、流變學的角度分析溶劑鑄膜之製程,實驗塗液主要有甘油水溶液和其他高分子甘油水溶液,使用的高分子有羧甲基纖維素(carboxymethyl cellulose, CMC)和聚丙烯醯胺(polyacrylamide, PAA),探討在甘油水溶液中加入CMC和PAA後對塗佈行為的影響,並與甘油水溶液的結果進行比較。
由甘油水溶液鑄膜實驗可發現溶劑鑄膜中主要有兩種塗佈上限缺陷:不穩定水窪(unstable pooling)和空氣滲入(air entrainment),低黏度低塗佈間隙時是不穩定水窪,且跟塗佈液珠的大小有關;高塗佈間隙和高黏度低塗佈間隙是空氣滲入為主,缺陷原因跟動態接觸角有關。根據力分析的結果,不穩定水窪的因素跟表面張力最為有關,而空氣滲入時黏滯力之效果會大於或約等於表面張力。
非牛頓流體的鑄膜實驗是以CMC甘油水溶液和PAA甘油水溶液為實驗流體,CMC甘油水溶液具有剪切稀化以及彈性力,經由實驗發現在Camax大於1時,彈性可以幫助擴大塗佈視窗,但過了一最佳值,塗佈視窗會隨著彈性增加而逐漸縮小,在塗佈間隙1000μm時是1000ppm的CMC塗佈速度最快且濕膜厚度最小,塗佈間隙500μm時則是500ppm的CMC塗佈速度最快且濕膜厚度最小。
另一部份研究是以PAA甘油水溶液配製成的伯格流體(Boger fluids)觀察彈性力對塗佈行為的影響。伯格流體的特性是黏度為定值但具有明顯彈性,因此在與同黏度的甘油水溶液作比較時可以更明確的看出彈性力的影響,實驗結果與CMC甘油水溶液相似,在Camax大於1時,一定之彈性力可以擴大塗佈視窗,由流場觀測也發現在同流量同塗佈速度下彈性增加時動態接觸角會變大,但是隨著彈性力增加塗佈視窗會縮小。而Camax小於1時,因為黏滯力不夠,彈性力無法幫助擴大塗佈視窗。
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