What are Structural Adhesives?
There is a common misconception that sealants and structural adhesives are the same, but that couldn't be further from the truth. A structural adhesive cures, or hardens, and permanently bonds the two pieces. A sealant, on the other hand, acts as a filler instead. That filler can eventually deteriorate and need replacing, whereas a structural adhesive should never need to be replaced.
With structural adhesives, there is more than one type. In fact, there are seven different types that you can choose from, depending on the project at hand. The seven structural adhesives include vinyl acetates, epoxies, anaerobics, phenolics, toughened acrylics, cyanoacrylates, and polyurethanes.
There are many benefits to using structural adhesives, and they include impact resistance, aesthetics, strength, efficiency for any process, design innovation, lightweight options, water resistance, and bonding between almost any material. Of course, to receive these numerous benefits, you must know the answers to specific questions before applying the structural adhesive.
Questions to Ask Before Applying Structural Adhesives:
- How hot or cold is the temperature where the job is being performed?
- Will the material that you are working with ever have exposure to saltwater or rain? How about the sun?
- Will any chemicals come into contact with the joint after using the structural adhesive? How about oil, gas, or other types of fuel?
- How often will the joint be cleaned using detergents?
- Are you trying to bond a device in the medical field? Is there concern for any toxicity levels?
- What are the stresses on the joint? Is the stress level higher than average?
- Will the joint you are working on be subject to vibrations or high levels of impact?
Once you know the answers to these questions, you can successfully choose a structural adhesive that meets your needs. Epoxies usually are better for metals, strength, and temperature resistance, while acrylics are suitable for plastics and shear metals. Urethanes are best for flexibility, unlike cyanoacrylates, which are typically used the most for plastics and metals that don't experience impact or significant temperature changes.
ASI – MP 55420SC Methacrylate Structural Adhesive
The ASI – MP 55420SC Methacrylate Structural Adhesive is a two-part adhesive that bonds everything from plastics to metals to composites. While the bonded area is durable, as well as impact and temperature resistant, it will also be flexible.
This structural adhesive has an off-white color when applied, and once it cures, it has a shear and tensile strength of more than 2,500 PSI. It is best to use this product in temperatures that range between sixty-five and eighty degrees Fahrenheit, but once cured, it can withstand temperatures from sixty-seven degrees below zero up to two hundred and fifty degrees.
The ASI – MP 55420SC is easy to apply, cures at room temperature, and there is no surface prep needed before applying it. This product can also be stored for up to one year after it ships, as long as it is not stored in temperatures lower than fifty-five degrees or higher than seventy-five degrees.
This structural adhesive is flammable, so care should be used to ensure to keep it away from heat and open flames. If any of this material spills, it should be cleaned up using a product that contains either N-methyl pyrrolidone or citrus terpene, before it has a chance to cure.
ASI – MP 55320 Methacrylate Structural Adhesive
The ASI – MP 55320 Methacrylate Structural Adhesive is another two-part adhesive that bonds to almost any type of material together. It has the same qualities and warnings as the structural adhesive mentioned above.
The one major difference is that the work time for this product is eight to twelve minutes, with a fixture time of twenty-five to thirty minutes. The product mentioned above has a work time of four to six minutes, with a fixture time of twelve to eighteen minutes. While the time you spend using this structural adhesive is longer, you will see a slightly higher shear strength rate when you are finished.
It is crucial while using either one of these structural adhesives that you are extremely careful to not get any of it in your eyes, on your skin, or in your mouth. If you do, you must go to the nearest emergency room immediately for treatment.
Choosing the correct structural adhesive is very important because not all of them will do what you need. Some are better with certain materials than others, while a few are better when it comes to flexibility, impact resistance, and temperature resistance. Therefore, ask the questions above before you even consider which structural adhesive to use on your next project.