The main difference between saturated and unsaturated polyester resin is that saturated polyester resins lack unsaturated double bonds in their chemical structure and crosslink through ester linkages, while unsaturated polyester resins contain unsaturated double bonds and crosslink through free-radical polymerization.
Polyester resin is a type of synthetic polymer material that is widely used in various industries for its versatility and durability. There are two types of polyester resins, and they are saturated and unsaturated.
Key Areas Covered
1. What is Saturated Polyester Resin
– Definition, Structure, Formation
2. What is Unsaturated Polyester Resin
– Definition, Structure, Formation
3. Similarities – Saturated and Unsaturated Polyester Resin
– Outline of Common Features
4. Difference Between Saturated and Unsaturated Polyester Resin
– Comparison of Key Differences
Key Terms
Saturated Polyester Resin, Unsaturated Polyester Resin
What is Saturated Polyester Resin
Saturated polyester resin is a versatile thermosetting polymer with a range of applications in various industries. It is a type of synthetic resin formed through the condensation polymerization of saturated diols, such as ethylene glycol or propylene glycol, with saturated dicarboxylic acids, such as phthalic anhydride, isophthalic acid, or adipic acid.
Saturated polyester resin is composed of a linear chain of saturated repeating units. The reaction of saturated diols produces it. The absence of double bonds or unsaturated groups in its chemical structure distinguishes it from unsaturated polyester resin.
Moreover, saturated polyester resins exhibit good mechanical properties, including high tensile strength, compressive strength, and impact resistance. They also offer excellent dimensional stability, making them suitable for applications where precise shape and size retention are crucial.
Saturated polyester resins demonstrate good resistance to various chemicals, oils, and solvents. This property also makes them suitable for applications in aggressive environments where exposure to corrosive substances may occur. They are also commonly used in the manufacture of composite materials, coatings, adhesives, and molded products.
What is Unsaturated Polyester Resin
Unsaturated polyester resin is a type of synthetic resin formed through the condensation polymerization of unsaturated diols with unsaturated dicarboxylic acids. Unsaturated polyester resin is composed of a linear chain of unsaturated repeating units. To be specific, it is produced by the reaction of unsaturated diols, such as propylene glycol or glycerol, with unsaturated dicarboxylic acids, such as maleic anhydride or fumaric acid. The presence of unsaturated double bonds in its chemical structure distinguishes it from saturated polyester resin.
Unsaturated polyester resins offer excellent mechanical properties, including high tensile strength, flexural strength, and impact resistance. The crosslinking of the polymer chains during curing enhances the resin’s strength and durability, making it suitable for demanding applications.
Similarities Between Saturated and Unsaturated Polyester Resin
- Both saturated and unsaturated polyester resins are derived from the condensation polymerization of diols with dicarboxylic acids.
- They share the same basic chemical structure consisting of ester linkages, which are formed during the polymerization process.
- Moreover, both resins belong to the category of thermosetting polymers.
- Both types of polyester resins require curing to achieve their final properties. Furthermore, the curing process involves the addition of a catalyst and an initiator to initiate the crosslinking reaction. During curing, the resins undergo a chemical transformation, forming a rigid and stable structure.
Difference Between Saturated and Unsaturated Polyester Resin
Definition
Saturated polyester resin is a type of synthetic resin formed through the condensation polymerization of saturated diols with saturated dicarboxylic acids, while unsaturated polyester resin is a type of synthetic resin formed through the condensation polymerization of unsaturated diols with unsaturated dicarboxylic acids.
Formation
Saturated polyester resin is formed through the condensation polymerization of saturated diols, such as ethylene glycol or propylene glycol, with saturated dicarboxylic acids, such as phthalic anhydride, isophthalic acid, or adipic acid. Unsaturated polyester resin is formed by the reaction of unsaturated diols, such as propylene glycol or glycerol, with unsaturated dicarboxylic acids, such as maleic anhydride or fumaric acid.
Chemical Structure
The chemical structure of saturated polyester resins does not contain any double bonds or unsaturated groups. It consists of a linear chain of saturated repeating units connected by ester linkages. The key characteristic of unsaturated polyester resins is the presence of unsaturated double bonds in their chemical structure. Furthermore, these double bonds are usually located between the carbon atoms in the main chain of the polymer resulting in a linear chain of unsaturated repeating units connected by ester linkages.
Conclusion
In brief, saturated polyester resins lack unsaturated double bonds in their chemical structure and crosslink through ester linkages. In contrast, unsaturated polyester resins contain unsaturated double bonds and crosslink through free-radical polymerization. Thus, this is the main difference between saturated and unsaturated polyester resin.
Reference:
1. “Polyester Resin.” Wikipedia. Wikipedia Foundation.
2. “Unsaturated polyester | Resin, Polymerization, Cross-linking.” Encyclopedia Britannica.
Image Courtesy:
1. “Unsaturated polyester” By DeStrickland – Own work (CC BY-SA 4.0) via Commons Wikimedia
Leave a Reply