In the last few years, pultruded products have become increasingly popular. In the years to come, results of recent surveys have found that these products are expected to become even more popular in the global manufacturing market.
Pultruded products offer several appealing features. For instance, they are extremely durable and environmentally friendly. Other properties of pultruded products can be attributed to the specific resins used in the manufacturing process.
The beauty of pultrusion is that profiles can be manufactured to meet specific needs. For example, if you need profiles that are fire-resistant, there are Tencom’s fire-retardant polyester, Vinyl Ester, Phenolic, or Polyurethane resin systems.
According to Verified Market Research, in 2020, the pultrusion market was valued at US$2 billion and is projected to reach $3.19 billion by 2028. Currently, the market is projected to grow at a compound annual growth rate (CAGR) of 4.9% from 2021 to 2028.
With pultrusion, there are a number of resins to choose from, so it is important to make the right selection, as each can affect the strength, durability, lifespan, and cost of the profiles. They have different chemical compositions and physical properties.
Before deciding to choose one or the other for your particular application, have a clear idea of the demands of your application ─ for example, fire resistance, corrosion resistance, UV resistance, and so on. Understanding the strengths of each resin will help you narrow down the list of critical material performance factors required for the final product, informing your selection.
In this post, we look at three pultrusion resins: polyester, phenolic, and vinyl ester. We’ve already covered polyurethane and epoxy.
Different Types of Pultrusion Resins
In the pultrusion process, common thermoset resins include:
- Polyester Resins
Polyester is the most widely used pultrusion resin in the composite manufacturing industry, accounting for 75% of total pultrusion resins. There are several reasons for this:
i. During the building of polymer chains, polyester resins are highly customizable. Pultruded products made with polyester resins offer excellent versatility and can be used in the manufacture of composite products.
Depending on the structure of their building blocks, these pultrusion resins offer versatility and other desirable features, making them even more popular. Words like Acrylated, Terephthalic, Neopentyl Glycol, Aliphatic, and others are adaptations to Polyesters that represent means of improving weathering, fatigue, flexibility, and toughness.
ii. Premium polyester resins, also known as Isophthalic polyester, boast excellent resistance to corrosion. Therefore, they are a popular option to be used in applications that are installed in highly corrosive and harsh environments.
By contrast, general-purpose polyester resins have average water resistance and are used to fabricate products for less corrosive environments. The downside of polyester resins is that they emit a strong odor during pultrusion.
- Vinyl Ester Resins
Vinyl pultrusion resins are the preferred option when long-term durability is required. Generally, the faster a pultrusion resin cures, the better the mold turnaround and production rates. Vinyl ester resin is developed through a series of chemical reactions that begin with the esterification of the desired epoxy resin and methacrylic acid.
In fact, vinyl ester resin is a sought-after pultrusion resin as it offers exceptional moisture resistance and also premium corrosion resistance. Either bisphenol-A or novolac chemistry with methacrylic acid is used to form the polymer. These characteristics make them ideal for the production of marine and coastal products like corrosion-resistant tanks and pipes, and other components.
Vinyl esters can be stretched and bond to core materials much more effectively than some polyesters, and delamination may be less of an issue. Compared with some polyesters, vinyl esters are less sensitive to temperature and humidity.
- Phenolic Resins
As the name suggests, phenolic resins are phenol-based. This means they cure through a condensation reaction. Phenol-based resins boast outstanding fire resistance and low-smoke emission properties.
For this reason, phenolic resins are commonly used as adhesives or matrix binders and are among the best pultrusion resins for FRP products. In addition, phenolic resins also have outstanding sound-damping, thermal insulation, and corrosion-resistance properties.
Why Use Pultrusion Resins in the Manufacturing Process?
Why exactly are pultrusion resins used? In simple terms, other than the excellent properties of each of the above resins, resins usually help transfer stress between the fibers.
Hence, they coat the fibers and bond them together so they can withstand harsh external factors such as corrosion. They also provide structural and thermal stability to the resulting composite. Depending on the application for which such profiles are used, different resins can be employed to meet your specifications.
For instance, because phenolics have thermal insulation and fire-resistance properties, they are often used in combination with other resins. So the resulting product can be both durable and fire-safe.
How are Resins Used?
As we’ve stated above, pultrusion resins are normally used to bond the reinforcing fibers and other composite materials together. They are at the core of the entire pultrusion process.
During pultrusion, glass-reinforced textiles or fibers are pulled through a pultrusion resin bath in a controlled process known as wet-out.
The process is monitored to ensure total-wetting out of the emerging reinforcing fiber. Any excess resin is removed afterward to expel trapped air before the impregnated glass-reinforced textiles are passed through a heated die to cure the combination of resins, catalysts, and any other fillers.
Once the composite is fully cured, it can be cut to the desired length or, if possible, to the desired size and shape.
The Takeaway
For premium-quality composite products, only high-quality pultrusion resins should be used. By looking at pultrusion manufacturing and some of the fiber reinforcements available, it is clear that there is a wealth of customization options depending on your specific needs.
Regardless of your project, selecting the right fiber reinforcement will allow you to achieve a high-performing product at a relatively economical cost.
Tencom is dedicated to making continued strides in the pultrusion industry, offering consistently high-quality products at competitive prices. We are serious about customer service and operate to stringent industry quality standards.
If you’re interested in learning what fiber reinforcements work best for your next project, contact us and get in touch with our team of experts.
