What is Epoxy Resin Crystallization?
Crystallization in epoxy resins manifests in different ways, depending on the formulation. Clear resins may develop a haze or slushy appearance, while heavily filled resins may exhibit a waxy, solidified consistency. It is important to note that crystallization is distinctly different from the cured state of an epoxy (which is hard and glassy). Despite its altered appearance, crystallization does not harm the resin and can be reversed effectively.
Since crystallization is a random occurrence, it does not necessarily affect an entire batch. You may receive a pallet containing multiple cans, with only one or two exhibiting crystallization. The unpredictability of this phenomenon highlights the importance of proper storage and handling.
Why Does Crystallization Occur?
Most liquid epoxies are considered supercooled liquids, meaning they remain in a liquid state even below their normal freezing points. However, various environmental and handling factors can trigger crystallization:
- Temperature Drops: A sudden decrease in temperature or prolonged exposure to cold conditions significantly increases the likelihood of crystallization.
- Physical Shock: Impacts such as dropping a can or aggressive handling can initiate crystal formation.
- Repetitive Mixing: Stirring or remixing resin without applying heat can inadvertently promote crystallization.
- Fillers and Additives: The addition of fillers generally increases the risk of crystallization, while certain diluents may help reduce it. However, the risk can never be fully eliminated.
Once initiated, crystallization typically progresses to completion unless disrupted. This process can be slow at room temperature but accelerates in colder environments.
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