振荡剪切下酚醛树脂冻胶成胶规律研究

摘要

In order to study the gelling behavior of the phenolic resin gel under dynamic conditions, the IKA oscillator was employed to determine the relationship between shearing time and the viscosity of phenolic resin gel, the difference between the gelation time under static condition and that under shearing condition, and the critical gelling velocity and the restorability of the viscosity after shearing. The results show that the gelation time of phenolic resin gel is delayed and the strength of the gel is reduced along with the increase of shearing velocity. Compared with the gelation time under static condition, the initial gelation time is advanced under low shearing velocity(10. 47～15. 71 s-1), and the initial gelation time is delayed under high shearing velocity(18. 32～23. 55 s-1). The gelation time is delayed and the gel strength is reduced with the increase of polymer concentration and cross linker concentration. The initial gelation time under oscillatory shearing is 2～4 hours shorter, and the initial viscosity is 0. 04 ～ 1. 00 lower than that under static conditions, the final gelation time is 2～6 hours longer and the final viscosity is 0. 65～0. 95 times lower than that under static conditions. There exists critical gelling velocity, when the shearing velocity is higher than the critical value, the phenolic resin gel is not able to form , and vice versa. The viscosity is able to restore after the shearing action is removed, and the restorability is declined with the extenion of shearing time, and the reduction of polymer concentration and crosslinker concentration.%为了考察酚醛树脂冻胶在动态条件下的成胶行为,采用IKA振荡器考察了剪切条件下酚醛树脂冻胶的粘度随时间的变化,对比研究了剪切条件下成胶时间与静态成胶时间之间的关系,确定了不同条件下酚醛树脂冻胶的临界成胶剪切速率及其经过剪切后粘度的恢复能力.结果表明,随着剪切速率的增大,酚醛树脂冻胶的成胶时间延长,冻胶强度降低.与静态成胶时间相比,低剪切速率下(10.47～15.71 s-1),初始成胶时间缩短；在高剪切速率下(18.32～23.55 s-1),初始成胶时间延长.随着聚合物和交联剂质量分数的增大,剪切条件下冻胶的成胶时间缩短,冻胶强度增大.同一配方的酚醛树脂冻胶的初始成胶时间比静态下的初始成胶时间短2～4 h,初始成胶粘度为静态下的0.04～1.00;最终成胶时间较静态的长2～6 h,最终成胶粘度为静态的0.65～0.95.存在临界成胶剪切速率,高于此剪切速率,酚醛树脂冻胶在剪切条件下不能成胶,且随着聚合物和交联荆质量分数的增大,临界成胶剪切速率增大.在临界成胶剪切速率下,将经过剪切后的酚醛树脂冻胶静置,粘度可以恢复,且随着剪切时间的增加,其恢复能力降低.随着聚合物和交联荆质量分数的减小,酚醛树脂冻胶经过剪切后静置体系粘度值逐渐降低,体系粘度的恢复能力减弱.