10 月 28, 2024 隆昌化工

快速回答: Epoxy–polythiol curing is a thiol–epoxy addition reaction, commonly accelerated by a suitable catalyst. Cure rate and properties depend on functional-group equivalents, catalyst, temperature, moisture, mixing, exotherm and network design.

环氧树脂和聚硫醇单体的反应机理?

环氧树脂和聚硫醇之间的反应机理主要涉及硫醇基团和环氧基团之间的相互作用。以下是详细的反应机理:
反应开始:

在聚硫醇与环氧树脂反应的过程中,叔胺上未共享的电子对会首先捕获硫醇基团的活性氢,从而在硫原子上产生阴离子电荷。

 

亲核加成反应:

带负电荷的硫原子与环氧树脂上的α碳原子发生反应,这个过程被称为亲核加成反应。

这一反应导致环氧树脂的三元环氧基团打开,形成两个羟基。

 

形成硫醇-氧键:

硫醇基团中的硫原子与环氧基团中的氧原子发生亲核加成反应,形成硫氧键,这是固化过程中的关键步骤。

 

形成交联结构:

环氧树脂中形成的两个羟基进一步与聚硫醇中的硫醇基反应,形成交联结构。

这种交联结构将聚硫醇与环氧树脂结合在一起。

 

固化结果

通过上述反应,聚硫醇和环氧树脂结合成一种耐磨、耐腐蚀、耐高温的固体材料。

 

反应特性:

聚硫固化环氧树脂的固化时间一般在几分钟到几小时之间,不需要高温或高压处理,因此在工业生产中得到广泛应用。

固化后的材料具有优异的物理和化学性能,如耐磨、耐腐蚀、绝缘性好等特点。

总之,环氧树脂和聚硫醇的反应机理是一个复杂但高效的过程,通过亲核加成反应实现两种材料的紧密结合和固化,并形成交联结构。

Control points in an epoxy–polythiol formulation

Start from functional-group equivalents rather than simple weight percentages. The thiol equivalent weight, epoxy equivalent weight and functionality distribution determine the theoretical ratio; fillers, pigments and other reactive ingredients must be included in the calculation where applicable.

Catalyst type and level strongly affect latency, pot life and cure speed. Mixing temperature, batch size and insulation can also change the exotherm, so a small laboratory cup result should not be transferred directly to a large mass. Record temperature versus time and check whether viscosity rise limits application before the nominal gel point.

Validate cure with more than surface touch. Depending on the use, useful checks include conversion or residual functionality, hardness development, adhesion, tensile or lap-shear performance, chemical resistance, glass-transition behavior and aging. Moisture, amines, acidic contaminants and storage history can alter the result, so raw-material controls and a defined mixing sequence are part of the cure design.

Use a documented polythiol as the formulation reference

The current CHLUMICRYL® Polythiol PM839 page provides a relevant polythiol reference. Request current equivalent-weight and handling data, then set the epoxy-to-thiol balance and catalyst level from controlled cure, pot-life and final-property trials.

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