What Temperature Can Epoxy Resist? Melting Point, Solidification And Operation After Solidification

2024 Author: Beatrice Philips | [email protected]. Last modified: 2024-01-09 13:15

To obtain a quality material with high strength and other useful qualities, epoxy resin is melted. To do this, you need to know what is the optimal melting temperature of this substance. In addition, other conditions necessary for proper curing of the epoxy are important.

Operating temperature limit

Of course, the temperature affects the working condition and proper curing of the epoxy resin, but in order to understand what temperature is the maximum for the operation of the substance, it is worth familiarizing yourself with its main technical characteristics.

• Polymerization of the resinous substance occurs during heating in stages and takes from 24 to 36 hours. This process can be completed in a few days, but it can be accelerated by heating the resin to a temperature of + 70 ° C.
• Correct curing ensures that the epoxy does not expand and the effect of shrinkage is virtually eliminated.
• After the resin has hardened, it can be processed in any way - grind, paint, grind, drill.
• The cured high-temperature epoxy mixture has excellent technical and operational properties. It possesses such important indicators as acid resistance, resistance to high levels of humidity, solvents and alkalis.

In this case, the recommended temperature of the working resin is a mode in the range from -50 ° C to + 150 ° C, however, a maximum temperature of + 80 ° C is also set. This difference is due to the fact that the epoxy substance can have different components, respectively, the physical properties and the temperature at which it hardens.

Melting mode

Many industrial, high-tech processes cannot be imagined without the use of epoxy resins. Based on the technical regulations, resin melting, that is, the transition of a substance from a liquid to a solid state and vice versa, is carried out at + 155 ° C.

But in conditions of increased ionizing radiation, exposure to aggressive chemistry and excessively high temperatures, reaching + 100 … 200 ° C, only certain compositions are used. Of course, we are not talking about ED resins and EAF glue. This type of epoxy will not melt. Completely frozen, these products simply collapse, passing through the stages of cracking and transition to a liquid state:

• they can crack or foam due to boiling;
• change color, internal structure;
• become brittle and crumble;
• these resinous substances also may not pass into a liquid state due to their special composition.

Depending on the hardener, some materials are flammable, emit a lot of soot, but only when in constant contact with open fire. In this situation, in general, one cannot talk about the melting point of the resin, since it simply undergoes destruction, gradually decomposing into small components.

How long does it withstand after curing?

Structures, materials and products created with the use of epoxy resin are initially oriented towards temperature standards established in accordance with accepted operating standards:

• the temperature is considered constant from –40 ° С to + 120 ° С;
• the maximum temperature is + 150 ° C.

However, such requirements do not apply to all resin brands. There are extreme standards for specific categories of epoxy substances:

• potting epoxy compound PEO-28M - + 130 ° С;
• high-temperature glue PEO-490K - + 350 ° С;
• epoxy-based optical adhesive PEO-13K - + 196 ° С.

Such compositions, due to the content of additional components, such as silicon and other organic elements, acquire improved characteristics . The additives were introduced into their composition for a reason - they increase the resistance of the resins to thermal effects, of course, after the resin hardens. But not only - it can be useful dielectric properties or good plasticity.

Epoxy substances of the ED-6 and ED-15 brands have increased resistance to high temperatures - they withstand up to + 250 ° C . But the most heat-resistant are resinous substances obtained with the use of melamine and dicyandiamide - hardeners that can cause polymerization already at + 100 ° C. The products, in the creation of which these resins were used, are distinguished by increased operational qualities - they have found application in the military and space industries. It is difficult to imagine, but the limiting temperature, which is not capable of destroying them, exceeds + 550 ° С.

Recommendations for work

Compliance with the temperature regime is the main condition for the operation of epoxy compounds. The room must also maintain a certain climate (not lower than + 24 ° С and not higher than + 30 ° С).

Let's consider additional requirements for working with the material

• The tightness of the packaging of the components - epoxy and hardener - up to the mixing process.
• The order of mixing must be strict - it is the hardener that is added to the resin substance.
• If a catalyst is used, the resin must be heated to + 40.50 ° C.
• In the room where the work is carried out, it is important not only to control the temperature and its stability, but also to ensure that the minimum humidity remains in it - no more than 50%.
• Despite the fact that the first stage of polymerization is 24 hours at a temperature of + 24 ° C, the material gains its ultimate strength within 6-7 days. However, it is on the first day that it is important that the temperature and humidity remain unchanged, therefore, the slightest fluctuations and differences in these indicators should not be allowed.
• Do not mix too large amounts of hardener and resin. In this case, there is a risk of boiling and loss of properties necessary for operation.
• If the work with epoxy coincides with the cold season, you need to warm up the working room in advance by placing packages with epoxy there so that it also acquires the desired temperature. It is allowed to warm up the cold composition using a water bath.

We must not forget that in a cold state, the resin becomes cloudy due to the formation of microscopic bubbles in it, and it is extremely difficult to get rid of them. In addition, the substance may not solidify, remaining viscous and sticky. With temperature extremes, you can also encounter such a nuisance as an "orange peel" - an uneven surface with waves, bumps and grooves.

However, by following these recommendations, observing all the necessary requirements, you can get a flawlessly even, high-quality resin surface due to its correct cure.