Adhesives and sealants are both usually applied using meter/mix dispensing machines provided for industrial projects. As such, these two terms are often used interchangeably. However, although the ways in which these materials work on an integral level are similar to each other, they come with significant differences. Indeed, while they are both often used for the same industrial applications, adhesives and sealants are not the same.

Adhesives are essentially like masking tapes – they are substances that have the capability to hold at least two surfaces together in a permanent and strong manner. On the other hand, sealants are substances that are capable of having two surfaces attached, thereby filling the space between them to deliver a protective coating or barrier.

To better understand how these two materials are distinct from each other, this article discusses the key differences between adhesives and sealants.

What are Adhesives?

As mentioned earlier, adhesives are substances that can bond two or more separate surfaces together by chemically overpowering the forces necessary to separate them. They are utilized in almost every product that consists of two or more parts since they are usually easier and more efficient to apply compared to mechanical fasteners. Moreover, adhesives have solid shear and tensile strength, which makes them ideal bonding materials for high-pressure situations.

What are Sealants? 

Unlike adhesives that merely hold two or more surfaces together, sealants are flexible substances that can block the flow of fluids through a gap, joint, or source by filling all the spaces between two or more separate surfaces. They have been traditionally utilized for waterproofing processes, but they can also be applied in thermal insulation and fire-retardants. Although sealants and adhesives are not the same, some sealants come with adhesive properties. Furthermore, while adhesives are generally stronger than sealants, the latter often provides the assembly with more flexibility.

Primary Differences Between Adhesives and Sealants

Even though adhesives and sealants are usually talked about under the same category of materials, they have substantial differences that make them fit for different applications or purposes. To better understand how an adhesive is distinct from a sealant, it is important to look into their specific differences in terms of flexibility, strength, and gap-filling.

• Flexibility: Sealants are much more flexible compared to adhesives. This is because sealants typically come with a paste-like consistency and contain an elastomer with a molecular structure, which is loosely cross-linked. This enables the sealants to fill gaps between the surfaces of substrates or components to form water-tight and air-tight barriers.

• Strength: Compared to sealants, adhesives have a lower elongation at break and higher shear strengths. Generally, sealants only have less than 1000 psi lap shear strength, while adhesives have more than 1,000 psi. This is a consequence of adhesives having greater cohesiveness, which basically means that their molecules bond together with greater attraction. On the other hand, sealants do not commonly provide adequate bonding force to hold two surfaces together because their molecular structure is less cross-linked. 

• Gap-Filling: Sealants have higher shrinkage rates. As a result, they are more effective than adhesives when it comes to filling small gaps between components or surfaces. The use of a sealant is essentially an effective means of making a space water- and air-tight. Meanwhile, pressure-sensitive adhesives are not suitable for encapsulating and gap-filling because they remain viscous and do not completely solidify.

Conclusion

Although adhesives and sealants are both used for industrial projects and are often used interchangeably, they come with different properties and advantages that make them quite distinct from each other. While adhesives are best for bonding two or more surfaces together because of their high shear strength and cohesiveness, sealants are the better choice when it comes to filling gaps and making them water- and air-tight. Knowing the differences between adhesives and sealants is important to determine which material is suitable for a particular application.

Should you need high-quality adhesives or sealants for whatever industrial or even household project you have, MOPI is here to help you! We are a reputable adhesive tape manufacturer and packaging supplier in Singapore that offers a wide range of premium yet affordable products, spanning from adhesives, sealants, and multi-purpose lubricants to PE laminated foams, polyolefin shrink films, and opp tapes.

Feel free to contact us anytime to learn more about our products, specifically our different bonding materials and packing tapes.