凍結乾燥法による微粒過塩素酸アンモニウムの調製 [in Japanese] Preparation of Fine Ammonium Perchlorate by Freeze-Drying [in Japanese]
Access this Article
Search this Article
高燃焼速度の過塩素酸アンモニウム (過安) 系コンポジット推進薬を得るためには微粒過安, 特に10×10<SUP>-6</SUP>m以下の過安が必要である.本実験では, 次のような凍結乾燥法により安全に球状の10×10<SUP>-6</SUP>m以下の微粒過安を調製する方法を開発した.この方法とは, 水や過安をほとんど溶解しない有機溶剤を過安水溶液中に分散させてO/W型エマルションを生成し, それを液体窒素に注ぎ凍結させ, その凍結物を凍結乾燥するものである.調製された過安の平均粒径 (<I>D</I><SUB>av</SUB> [m]) は, 過安水溶液と有機溶剤の界面張力 (σ [N・m<SUP>-1</SUP>]) によって決まり, 0.5×10<SUP>-2</SUP>N・m<SUP>-1</SUP>≦σ≦4.9×10<SUP>-2</SUP>N・m<SUP>-1</SUP>の範囲内で, <I>D</I><SUB>av</SUB>= 0.186 ×10<SUP>-6</SUP>で表された.なお, 界面活性剤の添加は, σの低下に有効であったが, トルエン以外の有機溶剤では, 調製過程中に泡沫が発生したために, <I>D</I><SUB>av</SUB>は上述の関係式からはずれて大きくなり, 球状以外の粒子が大半を占めた.
In order to prepare Ammonium Perchlorate (AP) composite propellant with a high burning rate, fine AP, of which mean diameter is less than 10 × 10<SUP>-6</SUP> m, is required. In this study, an attempt was made to prepare fine spherical AP with safety through a freeze-drying method. O/W emulsion was prepared by emulsifying with organic solvent as dispersed phase and AP solution as dispersion medium. Organic solvents used in this study barely dissolve AP and water. The emulsion was frozen with liquid nitrogen and the frozen emulsion was freeze-dried. The mean diameter (<I>D</I><SUB>av</SUB> [m]) of AP prepared depends on the interfacical tension (σ [N-m<SUP>-1</SUP>]) between organic solvent and AP solution. In the case of 0.5 × 10<SUP>-2</SUP> N · m<SUP>-1</SUP> ≤σ 4.9 × 10<SUP>-2</SUP> N · m<SUP>-1</SUP>, the relationship between Day and a is expressed by the following equation.<BR><I>D</I><SUB>av</SUB>=0.18σ×10<SUP>-3</SUP><BR>The addition of surface active agents is effective for a decrease in σ. However, foam formed on the emulsion during the preparation for all of the organic solvents used in this study except toluene. Consequently <I>D</I><SUB>av</SUB> deviated from the above equation and there was little spherical AP present. It was proved that the freeze-drying method is applicable as a safe preparation method for fine spherical AP.
- Chemical engineering
Chemical engineering 23(2), 163-169, 1997-03-10
The Society of Chemical Engineers, Japan