醇类低温保护剂对NaCl水溶液共晶的影响

为了研究低温保护剂对盐水溶液共晶的影响, 利用差示扫描量热法(DSC)对添加不同浓度的甘油、乙二醇、1, 2-丙二醇、1, 3-丙二醇和二甲基亚砜的NaCl 水溶液的共晶现象进行了研究. 发现NaCl 水溶液共晶是一个过冷随机过程,醇类和二甲基亚砜对之有抑制作用.保护剂浓度越高,共晶焓越小, 对共晶的抑制作用越大. 其中4种醇类保护剂的抑制能力从强到弱依次是甘油、乙二醇、1, 2-丙二醇和1, 3-丙二醇.其抑制能力的强弱主要由分子量/羟基数的比值决定, 其次受甲基影响. 二甲基亚砜抑制共晶的能力与乙二醇的接近. 研究发现升温过程中,三元溶液发生共晶体的玻璃化现象和反玻璃化现象.

The Influcence of Alcohol Cryoprotectants on Eutectic Crystallization of NaCl Aqueous Solutions Studied by DSC

In order to investigate the effect of cryoprotective agent (CPA) on the eutectic crystallization of salt solution, differential scanning calorimetry(DSC) is used to study the eutectic phenomena of NaCl aqueous solutions with different concentrations of glycerol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and dimethyl sulfoxide. It is found that the eutectic crystallization is a super-cooling and random process. Cryoprotective agent can restrain the eutectic crystallization of NaCl aqueous solutions. The higher the concentration of cryoprotective agents, the less the enthalpy of eutectic crystallization and the bigger the capability of restraining the eutectic crystallization. The restraining effects of cryoprotective agents on eutectic crystallization are different. The best is glycerol and then is ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol, respectively. The restraining capability of alcohols is largely determined by the ratio of molecular weight to number of hydroxyl group, and affected by the number of methyl group as well. The capability of dimethyl sulfoxide to restrain the eutectic phenomena of NaCl aqueous solutions is similar to that of ethylene glycol. It is also found that the glass transition and devitrification phenomena take place during the heating process.