AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

Adhesives vs. Sealants

Depending on whether your application requires the bonding of separate materials or to block the flow of gasses or liquids, it is crucial to use the proper adhesive or sealant. While adhesives bond two separate substrates together by chemically overcoming the forces of their separation, sealants block fluid flow through a surface, gap, or joint by filling in the space between the separate substrates. These two substances have many differences in their form and function which will be explored further in the following blog. 

To start, adhesives bond separate substrates by overcoming the forces that are required to separate them. Such materials are used in nearly every product or system that possesses two or more parts that need to be joined together without a mechanical fastener, and they tend to be easier to apply than fasteners because they involve less labor, time, and material costs. Adversely, sealants consist of a flexible, paste-like substance that is capable of blocking the flow of fluids through a surface, gap, or joint by filling in all the spaces between the two separate substrates. Though they are typically utilized in waterproofing applications, they are also seen in fire-retardants and thermal insulation. Though they are different from adhesives, sealants also have adhesive properties, while many adhesives technologies are able to be turned into sealants. Both these materials tend to be available as polyurethanes, methacrylates, epoxies, cyanoacrylates, silicones, and silane-modified polymers.

Despite being categorized under the same material category, adhesives and sealants are different in terms of their strength, flexibility, gap-filling capability, and overall applications. In terms of strength, adhesives possess higher shear strength than sealants at over 1000 psi, those of which are less than 1000 psi. Adhesives are overall more cohesive than sealants, meaning that their molecules stick together with much more attraction, and they are also more rigid and durable than their counterparts. Adhesives typically have a specific bonding purpose because they lack the bonding force to hold two substrates together and have the potential to become deformed under heavy loads. Additionally, sealants are more flexible than adhesives because they typically contain an elastomer, and since they have higher rates of shrinkage, they are used to make spaces air- and water-tight. On the other hand, adhesives are viscous and do not completely solidify which makes them inadequate for gap-filling purposes.

When deciding whether to use an adhesive or a sealant, there are several factors to consider, including whether you are performing a bonding operation, filling a gap between two or more substrates, or trying to keep moisture inside or outside of a component. When performing a bonding application, be sure to use a structural adhesive; on the other hand, applications intended to fill a gap between two items or to keep moisture in and out of a system should find an appropriate sealant. Moreover, sealants can also be used for thermal and acoustical insulation, fire-retardants, and electrical conductivity.

Those searching for quality sealants, adhesives, and many other parts for their applications can trust in NSN World, where we source all of our products from leading global manufacturers. With more than 2 billion new, used, obsolete, and hard-to-find items available for your immediate purchase, you can count on us to get you what you need quickly and efficiently. Our supply chain network spans the United States, Canada, and the United Kingdom, ensuring that we can expedite shipping times for domestic and international customers. With AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation, you can trust in the caliber of our services and offerings. Call or email us with any questions you may have, and begin the parts procurement process by submitting an Instant RFQ form today!


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