| 摘要: | 在本論文研究熱塑性聚氨酯(TPU)之高分子材料在超臨界二氧化碳中的發泡現象，改變操作條件下，探討孔洞結構的變化，並分析泡孔孔徑數據。發泡溫度為140℃到160℃、發泡壓力為3000、3750、4500 psi，洩壓方式考量速度與分段的組合；在不同的發泡溫度、壓力、及洩壓方式的組合下，造成發泡的結果差異很大，利用掃描式電子顯微鏡(SEM)觀察在不同條件下的泡孔形態，結果發現當發泡溫度上升時，泡孔平均大小（Davg）也會增加，但泡孔密度（Nf）卻減少；而一段洩壓的泡孔較為均勻，分段洩壓的泡孔則較為不均勻，洩壓的方式與次數也會影響到泡孔的大小；160℃、3000psi、飽和120min、先快速洩壓至0psi，再加回3000psi(再飽和30min)再快速洩壓至0為可達到最大泡孔的條件。
In this paper, research the foaming behavior of thermoplastic polyurethane (TPU) using supercritical carbon dioxide (scCO2), change the operating conditions, explore the change of pore structure, and analysis of cell pore size data.The foaming temperature is 140 ℃ to 160 ℃,the foaming pressure is3000, 3750, 4500 psi the pressure relief method considers the combination of the speed and the segmentation. At different foaming temperature, foaming pressure and pressure relief mode of the combination, resulting in a great difference in the results of the foam. and use the scanning electron microscope (SEM) to observe the cell morphology at various operating conditions. The results reveal that when the foaming temperature, the foaming pressure, and the saturation time all increase, but the depressurization rate is low, the cell average size (Davg) becomes larger but the cell density (Nf) becomes lower. A pressure relief of the cells are more uniform, Segmental pressure relief of the cells are more uneven, The way and the amount of pressure relief will also affect the size of the cell; 160 ℃, 3000psi, saturated 120min, the first rapid pressure relief to 0psi, and then plus back to 3000psi and re-saturated 30min finally rapid pressure to 0psi to achieve the maximum cell conditions. |
