冷冻干燥中升华界面的临界温度实验

Critical Temperature of Sublimation Interface in Freeze-drying

利用冻干显微镜（FDM）研究了二元水溶液冷冻干燥过程中升华界面的临界温度,采用差示扫描量热法（DSC）测量了溶液的共晶熔融温度和最大冻结浓缩溶液的玻璃化转变温度。实验结果表明,对于降温时发生共晶的溶液,临界温度为共晶熔融温度,否则将发生融化;对于降温时发生玻璃化转变的溶液,临界温度为塌陷温度,否则将发生塌陷。对于质量分数为5%蔗糖、10%葡萄糖、10%麦芽糖、10%聚乙烯吡咯烷酮（PVP）二元水溶液,微塌陷温度与塌陷温度的差值在2℃以内,微塌陷温度比玻璃化转变温度高1~3℃。

Freeze-drying microscopy（FDM） was used to investigate the critical temperature（Tcr） of sublimation interface during freeze-drying of binary aqueous solutions,and differential scanning calorimetry（DSC） was used to investigate the eutectic melting temperature（Tem） and the glass transition temperature of the maximally freeze concentrated solution（T′g）. The experimental results showed that if a solute crystallized from solution during freezing step,the critical temperature was the eutectic melting temperature,or else a meltback would occur.If the solute remained amorphous during the freezing process,the critical temperature was the collapse temperature,or else the amorphous phase would undergo viscous flow.For 5% Sucrose,10% glucose,10% maltose,10% PVP binary aqueous solutions,the microcollapse temperature（Tmc） and the collapse temperature（Tc） differed by less than 2℃,and Tmc was 1～3℃ above T′g.