部分水解聚丙烯酰胺弱凝胶交联动力学的流变学分析

用流变学方法对部分水解聚丙烯酰胺(HPAM)苯酚甲醛间苯二酚交联体系的弱凝胶化过程进行了研究,通过对基团转化率和高分子交联转化率的分析,发现凝胶化过程在接近凝胶点时,处于反应动力学的初期,这使得交联点增加的动力学是比较简单的.通过在不同聚合物浓度和交联剂浓度并在地层温度和矿化度条件下线性粘弹性行为的研究,得到了交联体系凝胶化动力学过程的完整数据,发现聚合物浓度与交联剂浓度对凝胶点与凝胶强度的影响比较类似,反映出交联点增加的共同动力学特征.复数粘度在一个诱导期后,是以指数上升的,类似一个一级反应的特征.产生交联的临界聚合物浓度约为250mg L左右.并提出了剪切粘度数学模型,可以描述凝胶化过程中流变性质的变化.

THE RHEOLOGICAL ANALYSIS OF GELATION KINETICS FOR PARTIAL HYDROLYZED POLYACRYLAMIDE WEAK GEL

The gelation rheology approach was employed to study the weak gel formation of partial hydrolyzed polyacrylamide(HPAM)/phenol/formaldehyde/resorcinol at various concentrations of HPAM and crosslinker under the conditions of the reservoir temperature and salinity.By analyzing the group conversion versus the conversion of the cross-linked macromolecules,it was revealed that near the gel point the gelation process was at the early stage of the reaction kinetics,which simplified the study of crosslinking kinetics.Comprehensive data of kinetic process were obtained as a result of the study of the linear viscoelasticity and nonlinear rheological behaviors.It is found that the effect of concentrations of HPAM and crosslinker to the gelation and gel intensity is similar,which reflects the common kinetic characteristics of the crosslinking reaction.After an induced period the complex viscosity rises as an exponential function of time,which is the characteristics of first-order reactions.The critical HPAM concentration for gel formation is around 250 mg/L.In addition,rheological models of complex viscosity and apparent viscosity in steady shear were introduced to describe the gelation process.