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Top 3 Differences between Thermoplastic and Thermoset

Posted on: July 25th, 2018 by byersbushblog

Are you one of those who constantly gets confused between thermoplastic and thermoset materials? Although they may sound similar, the reality is that there are some important differences that must be carefully considered to get the kind of result you are hoping for. With that in mind, let’s check out some of the details.

The Polymers

When we talk about polymers we are referring to the substances that have long chains of individual atoms that have chemical and heat resistant properties. These are also known for their durability, elasticity, and cheaper cost.

Polymers can fall into many categories based on the forces between the molecules like fibers, elastomers, thermosets, and thermoplastics. Let us focus on the last two categories and see their different applications and properties. By getting a clearer idea of the performance differences, it becomes easier to choose which a better option for your needs is.

Curing Process

The curing process involved for thermosets allows for the crosslinking of polymers that result in a chemical bond that cannot be reversed. This means that the resulting product cannot be reheated and remelted once finalizes. As such, it is an ideal process for applications that require high heat like appliances and electronics.

The pellets of thermoplastics on the other hand are softened and eventually turns into liquid as the applied heat is increased. During the curing process there is no chemical bonding that takes place so it is completely reversible. This means that it can be remolded and recycled without having adverse effects on the physical properties of the material.

Features

As far as thermosets are concerned, it has to go through a two-stage polymerization process to come up with the hard and brittle product. Using thermoset plastics increases the mechanical properties of a material by enhancing its heat and chemical resistance along with its structural integrity.

Often we see this material in sealed products because it is resistant to deformities and cannot be dissolved by organic solvents. Subjecting the final product to additional heat will cause it to burn and not melt. Products have a lower degradation point than melting point.

Thermoplastics on the other hand are prepolymerized so it does not have to go through that process again. This is why it can be remolded and recycled without affecting physical properties of the product. This material commonly provides shrink resistance, easier bendability, and higher strength.

Thermoplastic

It can also be used for low stress applications like plastic bags or in high stress requirements like in mechanical parts. This is possible because of its flexible and elastic nature, but it can be dissolved by organic solvents.

The final product will turn soft and melt when reheated because its melting point is lower than its degradation point. Normally you will see thermoplastics in solid pellet form before it turns into a liquid state.

Did you know that thermoplastic polyethylene is also used to enhance bulletproof vests to increase the hardness while ensuring that it remains lightweight?

Advantages

Both polymers obviously have their own advantages depending on the type of applications that you have in mind. So here are some you can consider:

  1. Thermosets
    • More resistant than thermoplastics at higher temperatures;
    • Extremely flexible design;
    • Applicable for thick and thin walls;
    • Beautiful appearance;
    • Dimensional stability;
    • Cost effective production and economical raw materials;
    • Well established production process;
    • Chemical resistance;
    • Liquid raw materials can be easily reinforced; and
    • Better adhesive and wetting properties.
  1. Thermoplastics
    • Highly recyclable;
    • More superior finishes;
    • Ten times higher impact resistance than thermosets;
    • Can be reshaped and remolded;
    • Chemical resistance;
    • Rubbery or hard crystalline surface finish options;
    • Environmentally friendly manufacturing process because of less emissions;
    • Easier to repair;
    • No refrigeration storage needed for uncured thermoplastics; and
    • Can blend well with other thermoplastics.

Disadvantages

It is important to take note that both materials also have its respective limitations based on the applications that will be used. Here are some of them:

  1. Thermosets
    • Not recyclable, remolded, or reshaped;
    • Harder to surface finish;
    • Liquid raw materials must be refrigerated;
    • Difficult to repair;
    • Complex and lengthy production process;
    • Susceptible to high-force impact;
    • Significant emissions during production; and
    • Cannot be welded with other thermosets.
  1. Thermoplastics
    • Comparatively more expensive;
    • Easily melts in significant heat;
    • Fiber reinforcement requires heat and pressure;
    • UV sensitive;
    • Structural failure can be expected for long-term or high stress load applications; and
    • Hazardous chemicals can leach out in the long term.

Thermosets

Powder Coating

In the context of powder coating, thermosets is commonly the choice because it can be applied thin but produces a hard surface. Thermoplastics on the other hand is usually avoided because of its cost and difficult applications.

Is there any reason why thermoplastics should be considered for powder coating? The answer is yes!

Thermoplastic powder coating can deliver incomparable performance compared to those that traditional thermosets can provide. This does not mean that thermoplastic powder should be the automatic choice. We still need to consider that each has unique features to suit various applications.

The longer chain molecules of thermoplastic powders compared to the short molecules of thermoset powders can result in structural differences that can prove to be vital in different applications.

Since thermoplastics are lighter than thermosets, fewer pounds will be required to achieve the same level of thickness for the coating. Thermoset coating is generally considered thin, strong and tightly linked.

The harder finish of thermosets allows for higher resistance to mar and scratches while thermoplastics offer better flexibility, better elongation, ductility, and higher impact resistance for the coating.

Both have significantly high adhesion rates allowing the powder to stick to the material regardless of its condition. Since both materials are dry particulates that melt and flow to result in a smooth and beautiful coating, the difference lies in one being recyclable. This means that thermoplastic powder coating becomes susceptible to extreme heat making it soft and returning to a liquid state at roughly 300 degrees. This is not the case with thermoset coating.

For applications that need high performance powder coating like those that can provide 5000 hours of salt spray protection for example or perhaps years of UV resistance with excellent resistance to impact, you can start considering thermoplastic powder coating solutions.

To make sure that you can the right solution at the best price possible, trust the experience of Byers Bush Powder Coating. Call them today!

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