Thermoset vs Thermoplastic: Which is Better?

Thermoset vs Thermoplastic: Which is Better?

When looking at thermoset vs thermoplastic, choosing the best material for your project will highly depend on the application, needed properties, and your overall budget. Both materials have been used to create products for everyday use and even specific purposes. There are many applications where either material will work, but some require the use of one over the other.

The main difference between thermosets and thermoplastics is what happens in the curing process and how they behave when heat is applied. They are also different regarding their properties, applications, and how they’re manufactured or processed.

Thermosets handle heat incredibly well after curing, as they do not melt when exposed to additional heat.

Thermoplastics begin as solids and are then heated and melted to be formed into new solid shapes once cooled. Unlike thermosets, if heat is applied to the material after it has cured, it will melt back to its liquid state.

What Is a Thermoset?

A thermoset is a high-performance polymer that cross-links during its curing process to form irreversible chemical bonds. At room temperature, it is a liquid and then hardens when heat and/or pressure is applied to make the material undergo a chemical reaction. The chemical change prevents the material from returning to a liquid state, making it impossible to reshape, recycle, or remold.

The chemical bonds also make the material stronger and more heat-resistant than its thermoplastic counterpart. The higher the cross-link density, the better the heat and chemical resistance they have. They can also be more rigid or flexible depending on the length and number of cross-link chains.

The main molding process used to make thermosets is reaction injection molding (RIM). Some materials can also be poured or sprayed. True to their name, they are set with permanent physical properties after the initial cure.

Common materials: epoxy, polyurethane, polyurea, polyaspartic, silicone

Advantages & Weaknesses

Advantages: 

• Durable. Thermosets are a good choice for parts that require dimensional stability and structural integrity at various temperatures. Due to their strong chemical bonds, they retain their strength, form, and shape in any condition, which makes them more durable.
• On-site uses. Thermoplastics can be applied to be cured on site without heating and/or can be retrofitted once they are in the field. They can also be sprayed through a plural component machine or injected while in the field. With easy molding characteristics, you can create large shapes, complex parts, or multipart components.
• Cost-effective. Setup and tooling costs tend to be lower. They can be molded at different tolerances, allowing for flexible product designs. Surface finishing is not required, which makes the process even more cost and time efficient.
• Versatile. There are a wide range of industries that use thermosets due to their chemical and thermal stability, as well as their various hardnesses. They have the unique advantage of being used as plastic, rubber, or foam. For example, you can make a thermoset elastomeric, but thermoplastics are incapable of achieving the same flexibility, so you would have to use a material like natural rubber. They have excellent flowability as a liquid, which allows them to fill all voids in a mold to copy small details that can’t be made with metal or thermoplastics.

Weaknesses: They might not be used over thermoplastics in instances where a recyclable or remoldable material is desired since they cannot be melted down to their original liquid state. Even though they have high strength, their rigidity can lead to reduced hardness at high temperatures. If they are overheated, they may begin to degrade but will not melt. This makes picking the correct thermoset product and the relevant HDT or heat cycling numbers important for your application.

Where Are They Used?

With good chemical resistance and thermal stability, they meet a variety of conditions for a range of applications. Their properties make them an excellent choice for high-heat applications or situations where heat is a factor. They are widely used in the aerospace, defense, electrical, automotive, and construction industries. They are a great alternative to metals and other plastics when complex, detailed parts and components are needed. Easy molding characteristics and on-site use get around many issues that you would encounter with thermoplastic materials.

What Is a Thermoplastic?

A thermoplastic is a solid polymer at room temperature (commonly stored as pellets) but becomes soft and pliable once heat is applied. There is no chemical bonding that occurs during the curing process, which means that it is reversible and only a physical change. Parts and products are made from this material by the processes of extrusion, thermoforming, or injection molding. Since they have a low melting point, they soften and deform when exposed to heat after curing, but their properties remain unaffected once the heat is removed.

Common materials: ABS, acrylic, nylon, polystyrene

Advantages & Weaknesses

Advantages: 

• Reusable. They are best known for their recyclability, as they can be melted down and molded into a new shape for reuse. Even after the material has been reshaped, its physical properties will not be negatively affected.
• Durable. They have great impact resistance and high strength while also being lightweight. They also resist shrinking as they offer good elasticity and flexibility. Since they are known for being versatile, they work well in both high and low-stress applications.
• Chemically resistant. They are desirable for their resistance to chemicals, detergents, and corrosion. They are the perfect material for applications that need protection from highly corrosive environments. While thermosets also have decent chemical resistance, it doesn’t compare to thermoplastics.

Weaknesses: Thermoplastics are not always the best or most cost-effective option, especially for low-volume or custom part production. The production process usually requires high heat and pressure, which can be more costly.

When exposed to heat and sunlight for extended periods, they experience UV degradation and soften or deform. They can’t handle heavy loads because they will stretch and weaken, which makes them more susceptible to creep and fractures.

They also struggle with application or retrofitting in the field. Primarily all work is done in the manufacturing setting and the original part may not be able to be modified in the field.

Where Are They Used?

Thermoplastics are ideal for applications that require recyclable and reusable materials. They are a good substitute for metal, as they can withstand corrosive conditions, though they are limited in high-temperature environments. They’ve also found use in the construction, electronics, medical, food and beverage, chemical, and automotive industries. They can be used to encapsulate rigid objects in electrical equipment or rope and belt production.

VFI Thermosetting Polymers

VFI has been manufacturing thermosetting polymers for almost 30 years. Our products have been used in a vast number of markets and industries. Most of our materials are two component liquids that become solid from a chemical reaction once combined and allowed to cure. They are strong, long-lasting, and third-party tested for quality assurance. If you have specifications for a needed material or questions on if you should be using a thermosetting polymer, contact VFI today.

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The Benefits of a Reusable Concrete Formliner

The Benefits of a Reusable Concrete Formliner

Learning more about reusable concrete formliner materials may help you decide if your project can benefit from using them. These tools are used in the construction industry to mold plain concrete into decorative concrete pieces. They are a cost-effective way to mimic expensive materials, such as brick, stone, and wood, using concrete. They can be used in a variety of cast-in-place, precast, and tilt-up jobs to enhance bridges, parks, residential areas, and other architectural concrete projects.

When choosing the best form liner material, you’ll want to consider how many times you want to use it. The types of materials used to make them play a big part in their longevity. Some materials are made to withstand hundreds of pulls, but others are only good for one use.

What Is a Reusable Concrete Formliner?

What separates reusable liners from single-use ones is their ability to generate multiple pulls before they wear down. Reusable formliners are made of stronger, more durable materials that last longer as long as they are properly cared for between uses.

What Is It Made Of?

No matter what material you choose, a good way to preserve a formliner for reuse is by applying a release agent before each use to limit adhesion to the concrete. The 4 main materials used include:

1. Urethane Rubber

Among all the materials used to make concrete formliners, urethane is the best option for reuse. It is a very high-quality, durable, and flexible material that is poured over a master to create panels of various shapes and sizes. It is the only material with multi-reuse potential, as a single liner can achieve as many as 100 pulls.

Urethane is great for custom patterns with high detail and depth, custom panel sizes, and, most importantly, large projects that require high reuse. Also, when it is bonded to a plywood backing, it makes it easier to move and work with.

2. Foam

As a lightweight material, polystyrene foam is easy to use and trim to the size you desire. It can be either hot wire cut or molded to generate a smooth finish on concrete, but it is generally limited in the shapes it can create if you intend to reuse the mold more than once.

It is a decent alternative to urethane rubber, but it must be coated with a 2-part urethane encapsulant of some kind, or it will be destroyed in the stripping process after one use. For this purpose, VFI offers VFI-2538 70 D EPS Form Hard Coat, which creates a uniform and releasable surface when casting concrete. When coated, foam liners can be reused if maintained, but they will not produce nearly as many castings as urethane rubber.

3. Plastic

The number of uses you’ll get from plastic will depend on the type of plastic used and its thickness. Plastics such as styrene and ABS are used in form lining, but only ABS is capable of multiple uses (usually up to 5). While it’s more cost-effective, it won’t provide nearly as many pulls as urethane.

Plastic formliners also provide concrete with a subtle, less detailed finish since they are made using a vacuum-forming process. Plastic is a desired material if you’re working on smaller projects where only basic patterns are needed and high reuse is unnecessary.

4. Fiberglass

Concrete formliners were once made of fiberglass sheets fastened to a form to create basic ribbed patterns. As new materials and techniques emerged, fiberglass took a backseat in the industry since it was much more time-consuming to use. Urethane rubber is easier to work with and produces results just as good in most applications. If more than 3 inches of relief is needed, fiberglass is preferred, though urethane is capable of high reliefs as well.

Benefits of Urethane Rubber

• Cost efficiency – While urethane rubber is a more costly material, its reuse potential more than makes up for the initial cost. With proper cleaning and storage, you’ll be able to maximize the life of your reusable concrete formliner.
• Durability – Most urethane formliners are made of solid rubber, so they have the strength to endure multiple pulls. The best reusable ones use higher durometer urethanes, typically between 70A – 90A. The harder the material, the more capable it is of maintaining its strength over time.
• Flexibility – Urethane can be more flexible or rigid depending on what kind of incuts you require in the design of your formliner. This increases the design potential you have while the material maintains its reusable nature.
• Versatility – Unlike other materials, urethane can copy extreme detail from a master and transfer those details onto wet concrete. You’re then left with concrete pieces that have the realistic finish you desire. There’s no limit to the concrete textures, patterns, or designs you can create with urethane. It is also capable of creating reusable concrete formliners of any shape or size needed.
• Consistency – Because urethane concrete formliners have such high reuse potential, they produce repeatable, uniform patterns after each use. Urethane reflects the same amount of detail in every cast, so large projects are desirable and seamless.

VFI Urethane Rubbers

VFI manufactures various urethane rubbers for the creation of reusable concrete formliners. Depending on the detail desired, we generally recommend the 50A-90A rubbers in our 2100 series. Our VFI-3170 and VFI-3180 rubbers are also excellent materials but must be used in controlled, high-production environments. If you’re interested in either product line, contact VFI today for more information.

Why Polyurethane Formliners Are the Best for Concrete Projects

Why Polyurethane Formliners Are the Best for Concrete Projects

Unlike traditional materials such as plastic or foam, polyurethane formliners offer a unique blend of qualities that make them the superior choice for concrete projects. One of urethane’s most remarkable characteristics is its flexibility. Due to its flexible nature, it can replicate complex patterns and intricate designs, including incuts, curves, and irregular shapes. It has unlimited design potential for replicating natural materials, pushing boundaries with abstract patterns, and even incorporating logos into architecture.

Other, more rigid materials can’t achieve the same highly realistic detail and definition on concrete surfaces. Urethane is also much more durable than any other material. With its resistance to abrasion, chemicals, and excessive wear, a single liner withstands multiple uses.

How are Urethane Formliners Made and Used?

Polyurethane formliners are made of a high quality, two-component material that combines isocyanate and polyol, which forms a liquid rubber that is poured into a mold and over a master. The liquid flows into all voids and contours every line to pick up every minor detail, including the porous nature of rocks, creating a perfect replica. Urethane cures at room temperature and comes in a range of hardnesses to fit a variety of application needs.

Before casting concrete into the new mold, it’s recommended that an acceptable release agent be used on the face, edges, and ends before each cast. Do not over-apply, as this may create pooling in the mold that will cause surface voids or bug holes. These voids prevent the concrete from copying all the details from the urethane.

The formliners are generally placed inside formwork before the concrete is poured. They must be properly aligned and secured for the best results. Large liners are usually attached to plywood backing since they weigh more and are less flexible. Plywood allows for attachment points in order to pick up the liners with machinery for precise placement and increased size. Using larger liners this way also allows for a quicker set-up and application on larger projects.

Once the concrete hardens, the formliner is removed, and all the details are transferred onto the surface. Urethane’s elasticity simplifies the stripping process, allowing it to easily release from intricate details and undercuts in the concrete for damage-free demolding. These formliners can also be inverted to generate different, less predictable patterns on the concrete. When using urethane, it’s much easier to avoid noticeable seams in the design as well, especially if you’re using large panels of the material. When plastic is used, more effort goes into making larger forms, as an adhesive must be used to glue several pieces together.

Where Are They Used?

Polyurethane form liners see the most use in large projects and areas with a lot of square footage to cover. If you need long spans or a seamless appearance in the concrete, urethane is the best option capable of fulfilling these requirements. It is a cost effective choice for any project that requires a high number of reuses.

Urethane is the best material for producing high detail and relief for projects, especially when a certain level of realism is needed. There’s almost no limit to where urethane can be used, including tilt-up, cast-in-place, and precast applications. Other instances where urethane makes a great form lining material include:

• Architectural facades. Add depth and character to flat, plain concrete surfaces on the exterior of buildings and give them a new identity.
• Landscaping. Craft inviting outdoor spaces such as charming pathways with natural rock formations in retaining walls to connect with surrounding landscapes.
• Interior design. Enhance plain walls and columns and turn them into a stunning focal point for indoor spaces such as hotels, residences, and shopping centers.
• Beautify utilitarian structures such as bridges, tunnels, and public spaces with artistic, textured elements.

How to Take Care of Your Formliners

A urethane formliner’s reusability will depend on how it’s used, how it’s cared for, how detailed it is, and the job site conditions. Key steps to preserve the life and quality of the liners include:

• A release agent should be applied before each use for easier demolding and to prolong the life of the liner. Cleaning the release agent off after use is also essential, as some release agents can be reactive and degrade the material over time.
• A clean liner will last longer and produce excellent results each time. Proper cleaning after each use removes concrete dust and buildup, preventing debris from affecting the detail of subsequent pours. Clean with hot water, soap, and a natural bristle brush. Never use a wire brush or harsh chemicals that might damage the urethane.
• Be careful and gently pry the formliner from the concrete in the stripping process. Peeling it back can create additional stress, reducing its usefulness over time.
• The form should be removed within 24 hours after the concrete has cured, or stripping may be difficult. While urethane is durable, you want demolding to be easy to keep the detail intact.
• Proper storage is also required to maintain its usability. Store it flat and in a clean, temperature-controlled environment. Do not let it sit face up in the sun for long durations of time. UV rays deteriorate urethane and may cause it to expand and fall apart.

VFI Polyurethane for Concrete Projects

VFI manufactures several lines of urethane products not just for use in form lining. The type of rubber you choose for your project will depend on your production process and the detail you require. Our 2100 series 55A-70A rubbers can produce advanced detail for highly aesthetic concrete pieces. Our 2100 series 70A-90A rubbers are also great for concrete projects but offer basic detail at lower pour thickness minimums. If you’re interested in these materials or softer rubbers for cast and manufactured stone applications, contact us today.