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Friday, January 22, 2010

Definition of Pot Life

Pot life or working life is the available time to process a reacting thermosetting formula.

Once the ambient cure temperature is reached and the crosslinking reaction begins, pot life describes the time available before the mixture becomes intractable or otherwise difficult to process.
For example, the pot life of a coating is the time during which the viscosity remains low enough to allow for easy brushing or spraying. In a molding compound, the working life represents the amount of residence time available in the molding machine before the material must be injected into the mold in order to have trouble-free molding and/or a defect-free part

Tuesday, January 19, 2010

Definition of Shelf Life

Shelf life is an arbitrary time for practical storage of a thermoset system.

Shelf life derives from the storage concept; i.e., how long can a thermoset be left on the shelf before it becomes difficult or even impossible to use in the intended application.

The term can refer to a one-can system (e.g., a phenolic molding compound must be molded within 1 year of compounding) or a two-can mix that must be set aside for a few hours before use.
Shelf life is also used to describe the storage stability of unmixed components of a thermosetting resin system if there is some threat to their reactivity as a consequence of the storage. For example, some curing agents are very hygroscopic and will lose reactivity if airborne moisture were to penetrate the storage container.