%0 Journal Article %A Miaomiao LUO %A Ning GUO %A Yi XU %A Daoping LIU %T Effects of graphene oxide on crystallization behavior of VS55 during cooling and warming %D 2019 %R 10.11949/j.issn.0438-1157.20180612 %J CIESC Journal %P 370-378 %V 70 %N 1 %X

The effects of cooling and warming rates(5,10,25,50 and 100℃/min) as well as the concentration of graphene oxide(GO) (0.01,0.1,1 and 5 mg/ml)on the crystallization of VS55 were studied by differential scanning calorimetry (DSC) and Cryomicroscope during both cooling and warming process. The results showed that: (1) As cooling and warming rates rised, both the freezing crystallization enthalpy Hf and the recrystallization enthalpy HTd became smaller. (2) For the case of cooling 2.1 mol/L VS55, the larger the concentration of GO, the more the crystallization of the 2.1 mol/L VS55 solution was, and the initial freezing temperature of the solution was increased obviously. For 4.2 mol/L VS55, however, the crystallization enthalpy Hf presented a trend of first dropping then rising when increasing GO concentrations. And GO has little effect on both freezing crystallization during cooling and recrystallization during warming for 8.4 mol/L VS55. (3) For the cases of higher concentrations of GO as well as lower concentrations of VS55, the crystal growth inside VS55 was inhibited more significantly during warming. For example, when adding 5 mg/ml GO, the recrystallization enthalpy offrozen 2.1 mol/L VS55 reduced by 14.55 J/g, that of 4.2 mol/L VS55 reduced by 7.95 J/g, which was close to 6.91 J/g of 8.4 mol/L VS55. In general, GO and VS55 concentrations mainly affect the growth of ice crystals during the cooling process, but the main factors, which affects the devitrification or recrystallization during the rewarming process, include the concentration of VS55 and GO as well as the cooling and warming rates.

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