Liu Changsheng, Gai Wei, Pan Songhua, Liu Zisheng
Institute of Biomaterials, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Biomaterials. 2003 Aug;24(18):2995-3003. doi: 10.1016/s0142-9612(03)00125-x.
The exothermal behavior in the hydration process of calcium phosphate cement (CPC) and their effect factors were investigated systematically. One CPC formulation is composed of tetracalcium phosphate (TECP) and dicalcium phosphate anhydrous (DCPA), and its hydration reaction is an exothermic reaction. Hydration includes five processes, namely, the start, induction, acceleration, deceleration and the terminating process. The introduction of hydroxyapatite (HAP) as crystal seed shortens induction and advances on the reaction peak position, which resulted from the introduction of crystal seed that reduced the activation energy of heterogeneous nucleation. The increase in temperature not only makes the reaction advance but also enlarges it. The activation energy of the hydration reaction is 176kJ/mol by calculation. The particle size of the raw material and the ratio of calcium to phosphate in the specimen have large effects on the hydration process. Decrease in particle size of TECP and in the ratio of calcium to phosphate resulted in marked acceleration of reaction and made the reaction peak advance evidently, but the effect of particle size of DCPA is not so remarkable. Based on the heat liberation in the hydration of CPC specimens taking Ca/P as 1.5 and 1.67, the standard mole enthalpies of formation of TECP and calcium-deficient hydroxyapatite are -5908 and -11,119kJmol(-1), respectively.
系统研究了磷酸钙骨水泥（CPC）水化过程中的放热行为及其影响因素。一种CPC配方由磷酸四钙（TECP）和无水磷酸二钙（DCPA）组成，其水化反应是放热反应。水化包括五个过程，即起始、诱导、加速、减速和终止过程。引入羟基磷灰石（HAP）作为晶种缩短了诱导期并使反应峰位置提前，这是由于晶种的引入降低了异相成核的活化能。温度升高不仅使反应提前，而且使其扩大。经计算，水化反应的活化能为176kJ/mol。原料的粒径和试样中钙磷比对水化过程有很大影响。TECP粒径减小和钙磷比降低导致反应明显加速，使反应峰明显提前，但DCPA粒径的影响不显著。基于Ca/P为1.5和1.67的CPC试样水化过程中的热释放，TECP和缺钙羟基磷灰石的标准摩尔生成焓分别为-5908和-11119kJmol（-1）。
