高岭土基地质聚合物聚合动力学初探

Reaction kinetics of kaolinite-based geopolymer with different active SiO_2/Al_2O_3 ratios

以偏高岭土为原料,掺杂一定量的活性SiO2和Al2O3制备了地质聚合物。根据所测不同的Si/Al摩尔比体系聚合反应过程中电导率随时间的变化关系,将聚合过程分为4个阶段:碱溶阶段、硅铝凝胶基团形成阶段、聚合反应阶段和网络状结构优化阶段。对聚合反应阶段建立动力学模型,计算出不同的Si/Al摩尔比体系聚合物的表观活化能,并测定了各护龄期的抗压强度值。研究结果表明,Si/Al摩尔比为1∶1时,G1-MK试样的表观活化能最小,所测抗压强度值最大;Si/Al摩尔比为1.6和0.8时,试样表观活化能最大,所测抗压强度值最小。而聚合反应表观活化能的大小间接反应了聚合反难易程度,说明所提出的动力学模型有一定的参考价值。

Geopolymers, prepared from metakaolin, active SiOe and A12Oa. According to the conductivity changing varying as the time, the process of polymerization reaction could be divided into four stages, alkali solution stage, aluminosilicate gel forming stage, polymerization stage, net structure forming stage. Kinetic models were established based on the stage of polymerization which this paper had put forward. The results show that the apparent activation energy of samples G1-MK which the Si/A1 ratios is closer to 1 was the smal- lest and the compressive strength was the biggest. The apparent activation energy is maxi- mum when the Si/A1 ratios is to 1.6 and 0.8 and the compressive strength was the smallest. The apparent activation energy of polymerization reaction had a close relationship with the degree of the polymerization reaction, which had been validated on the compressive strength of samples.