Testing standards and methods for polythiol

2022-08-02

1. PH value testing

Measure polythiol’s acid value according to GBT6473-2008

2. Gel time testing

The surface drying speed is not a major indicator in application of adhesives, we usually focus on system’s gel time

3. What epoxy resin is requested for gel time measurement? And testing method?

Weigh one gram for each E51 epoxy resin & modified polythiol curing agent, mix them per 1:1 ratio and stir it evenly for 10 seconds on a gel apparatus at an ambient temperature of 25 °C, get the readings from gel apparatus afterwards.

4. Water content of polythiol curing agent

In adhesive applications, water content is not so commonly tested as volatiles. First, take a 0.1mm aluminum sheet to make a 45*45mm square aluminum box, weigh 5g of polythiol, vacuum (<0.095MPa), dry it at a constant temperature of 120 °C for 2 hours, then measure the volatile content. (Accurate to 0.001 grams)

5. What is the effect of viscosity on adhesive applications, such as the difference between CPS 9500 and 11000 in use? Suggested rotor size for viscosity testing?

Influence on gel time and mechanical properties of post-curing system. When the same catalyst is used, the higher the viscosity, the shorter the gel time, vice versa.

Influence on mechanical properties: set same gel time for each system, compare the mechanical properties of each, low viscosity will result in decreased mechanical performance;

Influence on the fluidity of glue: too low viscosity may lead to leakage of glue during mixing or sub-packaging. We recommend viscosity of 11000-15000 for general applications, different viscosity can be customized for some special applications.

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