High-strength composite adhesives from Permabond

Composite materials such as carbon fibre, fibre-reinforced plastics (FRP) and glass-reinforced plastics (GRP) are becoming increasingly popular in industry, mainly due to their low weight and high strength. They are frequently used in the automotive, aerospace, construction, and energy industries, among others. Permabond ET5428 and ET5429 provide exceptionally high strength on these materials

Due to their rubber toughening, ET5428 and ET5429 offer more than just very high bond strength, however. They also provide excellent environmental, impact and vibration resistance - key factors when we consider the type of applications composites tend to be used in, such as cars. They also offer good heat resistance for epoxy adhesives, continuously withstanding up to 120degC.

Permabond ET5428 and ET5429 also display exceptionally high peel strength, especially when compared with standard epoxy adhesives. Even when compared to MMA structural acrylics, which are known for their high peel strength, ET5428 and ET5429 perform better. Their high peel strength means that both products are more adept at coping with difficult joint designs.

In addition to their toughness and durability, both ET5428 and ET5429 bring a lot to the table. They are lightly thixotropic, with excellent flow control. This makes them very smooth and easy to dispense by hand - meaning no need to go to the gym before you can get them out of the nozzle! This thixotropy also makes them well suited to vertical applications, as the adhesives don't slump or sag after applying. They're also highly suitable for any application requiring a gap fill.

In terms of substrates, these two epoxies bond a lot more than just composites. Materials bonded effectively by ET5428 and ET5429 include: ceramics, metals such as aluminium, mild steel and stainless steel, plastics like polycarbonate and PEEK, nylon, timber and many others.

Bonding dissimilar materials is also not an issue for these products, so you can gladly bond composites to metals or to plastics, for example. The rubber toughening built into both products gives them the strength and flexibility to handle differences in thermal contraction (CTE) between substrates. This ensures a strong, long-lasting bond that withstands changes in temperature from weather or processes like thermal cycling.

When to choose which?

Permabond ET5428 and ET5429 are products offering broadly similar benefits - they both offer exceptional bond strength and durability on composites and many other substrates. However, there are some key differences between them to consider when choosing which one to use.

The biggest difference between the two adhesives lies in their curing speed. ET5428 cures quickly, reaching handling strength at room temperature in 30-45 minutes. On the other hand, ET5429 offers a very long open time, reaching handling strength at room temperature after between 6 and 10 hours. Depending on the needs of your project, you may require an adhesive that cures more quickly or more slowly. For example, if you're bonding a larger surface area, you may need an adhesive with a longer pot life. Note that, being epoxies, a warmer environment will speed up the cure of both adhesives - at 60degC a full cure is reached in 1 hour (ET5428) or 2 hours (ET5429).

In terms of colour, ET5428 is available in both cream and black. This makes it suitable for colour matching to key composite materials such as carbon fibre, FRP and GRP. ET5429 is charcoal, matching carbon fibre very well.