EN ISO 2535 Plastics - Unsaturated Polyester Resins - Measurement of Gel Time at Ambient Temperature

The EN ISO 2535 standard developed by the International Standards Organization (ISO) defines test methods for measuring the gel time of unsaturated polyester resins at ambient temperature, ie in the range of 18 to 30 degrees, under certain conditions. If the referee temperature is required, measurements are made at 25 degrees.

For the purposes of this international standard, the expression gel time at ambient temperature refers to the time elapsed between the end of the addition of an initiator to a resin and the moment when the viscosity reaches 50 Pas.

In this test method, the time required for unsaturated polyester resins to reach 18 Pas viscosity at ambient temperature (usually in the range of 30 to 50 degrees) is measured. This time is conventionally regarded as the viscosity time corresponding to the gel state.

There are four measurement methods in the developed EN ISO 2535 standard:

Method A1 uses an auto-release device in which a glass rod is rotated in the resin mixture in a test tube and the rotation of the glass rod is automatically stopped when a viscosity of 50 Pas is reached.
Method A2 also uses an automatic release device, but the resin mixture is in a beaker.
Method B1 uses a continuous measuring device in which a glass rod performs a horizontal oscillating motion in a resin mixture contained in a test tube. In this method, viscosity is measured continuously to obtain a viscosity plot against time.
Method B2 also uses a continuous measuring device.but the resin mixture is in a beaker.

Determination of gel time is one of the most important technological parameters of polymer resins. The methods described above for determining gel time provide very useful information in the development and quality control of curing processes. Each method has its capabilities and limitations, and the accuracy and ease of use of these methods are considered.

Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer services for measuring the gel time of unsaturated polyester resins at ambient temperature within the scope of the EN ISO 2535 standard , thanks to our trained and expert staff and advanced technological equipment.