When selecting an initiator, the characteristics of the initiator must be matched with the reactivity of the resin. The resin used for molding at room temperature must be equipped with an initiator with high activity and capable of generating redox reaction with accelerator. There are many types of resins for thermoforming, and there are many types of initiators available. For a resin, the effect of using benzoyl peroxide may not be good. It is better to use t-butyl peroctoate with the same half-life. Therefore, it needs to be tested, carefully compared and evaluated. In general, the resin is reactive, it is required to choose a less active initiator to prevent free radicals from generating too quickly, which cannot be fully effective during the resin curing process, and the lack of initiator in the later stage.
Resin production plants generally make recommendations for the variety and amount of initiators for each resin they produce. They are described separately in the following and next chapters of each application.
Shelf life of resin
The storage period and storage period of resin are two different concepts. The storage period refers to the validity period of resin products that can be stored in the warehouse and during transportation, generally about 6 months. For storage, no initiator should be added to the resin. The storage period refers to the effective time for the user of the resin to process the product from the processing initiator to the time when the resin starts to lose fluidity. This effective storage time can also be called the service life, which is required by the processing technology and must be met. Therefore, it is also the main factor for the selection of initiators.