Takeuchi M
Shika Rikogaku Zasshi. 1978 Oct;19(48):279-89.
A better understanding of setting process of zinc phosphate cements is important to obtain optimum conditions of manipulation. Viscosity changes of zinc phosphate cements in setting process were investigated using a rotational viscometer in various conditions. The results obtained were as follows. 1) The viscosity of the cement mixture increased exponentially as a function of time. 2) The setting process of the cements was characterized by two parameters, the coefficient of setting speed and the setting time. The coefficient of setting speed was defined as the slope of the linear portion of log viscosity versus time curve, and the setting as the time required to reach a certain level of viscosity after the start of the mixing. 3) Shear rate was observed to affect on the time-related changes of viscosity. As the shear rate increased, the coefficient decreased and the setting time increased. These changes were more remarkable in the lower range of shear rate. 4) The coefficient of setting speed was found to be dependent on environmental temperature in accordance with Arrhenius' low. 5) Apparent activation energy calculated 16.41 kcal/mol by Arrhenius' equation. The coefficient increased by a factor of 2.6, when the temperature was raised from 20 degrees to 30 degrees C. 6) A decrease of the P/L ratio caused the logarithm of the coefficient to increase linearly and the setting time to decrease. 7) All the four commerical zinc phosphate cements tested showed different values of both the coefficient and the setting time.
更好地理解磷酸锌水门汀的凝固过程对于获得最佳操作条件很重要。在各种条件下使用旋转粘度计研究了磷酸锌水门汀在凝固过程中的粘度变化。得到的结果如下。1）水泥混合物的粘度随时间呈指数增加。2）水泥的凝固过程由两个参数表征，即凝固速度系数和凝固时间。凝固速度系数定义为对数粘度与时间曲线线性部分的斜率，凝固时间定义为混合开始后达到一定粘度水平所需的时间。3）观察到剪切速率会影响粘度随时间的变化。随着剪切速率增加，系数减小，凝固时间增加。这些变化在较低剪切速率范围内更为显著。4）根据阿仑尼乌斯定律，发现凝固速度系数取决于环境温度。5）通过阿仑尼乌斯方程计算出的表观活化能为16.41千卡/摩尔。当温度从20摄氏度升高到30摄氏度时，系数增加了2.6倍。6）P/L比的降低导致系数的对数线性增加，凝固时间减少。7）所测试的所有四种市售磷酸锌水门汀的系数和凝固时间值均不同。
