When it comes to selecting a structural adhesive, you’ll face several choices. In fact, the choices often seem endless. Whilst it’s nice to have so much variability, it can make it difficult to decide.
Here at Forgeway, we manufacture industrial adhesives including structural. We know how difficult it can be to decide the right structural adhesive for your application.
That’s why we like to narrow it down to just three options:
Each option has its advantages and disadvantages. This article will analyse each option to help you understand which structural adhesive type might be best for you.
By the end of the article, you’ll understand how the options differ. You’ll also understand the pros and cons of each option. The article will help you decide the best adhesive type for you.
Before diving into the details, it’s essential to grasp why we often compare epoxy, acrylic (MMA), and polyurethane adhesives. As we’ve explained in previous articles, some people offer a broad description of structural adhesives. The range of different adhesive types that could qualify as ‘structural’ is very extensive.
After you boil it down and understand what ‘structural’ means, you’re left with three main adhesive types; Epoxy, Acrylic, and Polyurethane. We’re not saying these are the only type of structural adhesive. We’re merely saying these are the main candidates when identifying structural adhesives.
All three belong to the structural adhesive category. That’s for certain. They all intricately fuse with the structures they bond, creating a bond that typically outlasts the lifetime of the structure being bonded.
These adhesives are typically available as two-component adhesives. Although you can get single-component variations too.
The main reason behind their comparison lies in their robust strength. Each chemistry can achieve lap shear strengths exceeding 20 MPa, powerful enough to rival a weld in the right circumstances.
While they share similarities, epoxy, acrylic (MMA), and polyurethane adhesives all possess distinct differences.
Two-component epoxy adhesives consist of epoxy resin and hardeners (often amine), facilitating curing and bonding. Single-component epoxies rely on an external factor like heat or UV to initiate the curing process.
Two-component Acrylic (MMA) adhesives are similar to epoxies. They employ an acrylic resin combined with hardeners for curing and bonding. It’s rare to find single-component acrylic adhesives.
Polyurethane adhesives, on the other hand, leverage a polyol and isocyanate to trigger curing and bonding. Single-component structural polyurethanes rely on atmospheric moisture to start the curing process.
As you can see, they are similar but have some distinct differences. These different chemistries possess different characteristics. We’ll assess these different characteristics in more detail below. However, you can see a snapshot of the differences in the graphic here.
The range of different epoxy adhesives available is massive. It’s difficult to describe the pros and cons of epoxies as the variations display different characteristics.
The below advantages and disadvantages are a holistic view of epoxy adhesives. There may be some variations that don’t possess the following characteristics.
Similar to epoxy adhesives, there are several different types of acrylic adhesives available. Whilst the characteristics again vary, there are common traits associated with acrylic adhesives.
Structural polyurethane adhesives are often two-component. Whilst they are still the same chemistry as single-component polyurethanes, the characteristics will differ.
In this section, we are focusing on two-component polyurethane adhesives rather than single-component variations.
Now you understand the key differences between each structural adhesive type. You also understand the pros and cons of each option. Now it’s time to use that knowledge. But this is where it gets difficult.
Here at Forgeway, we manufacture each of these adhesive types. We understand that the points above give a brief overview of each chemistry type.
If you’re looking for more information, we linked articles that will help you understand each adhesive type. If you can’t find the links, we have listed hyperlinks for you:
Alternatively, if you’re not sure what characteristics you need in an adhesive type, read the article below. It will help you understand what you need to consider when choosing an adhesive.
Or you can reach out to an adhesive expert from Forgeway. They can help you understand your application requirements and suggest a suitable adhesive type to solve your challenge.
We look forward to helping you!