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Polyester Resin Vs. Epoxy Resin

Saptakee Sengupta Jan 27, 2019
This write-up mentions the differences between polyester resin and epoxy resin. These two are resins having different chemical and physical properties, and hence, their applications also vary.
Polyester is a chemical compound made up of long chains of polymers, that have been formed by condensation reaction. These polymers are known as condensation polymers, and the actual process is known as condensation polymerization.
Polyester resins have unsaturated bonds that make their structure flexible. Epoxy resins are compounds that are formed as the products of a reaction between an epoxide and a polyamine, by applying external heat in the form of electron beams or irradiation.
Polyester mainly differs from epoxy on the basis of its adhesive properties, due to which, its industrial application is much larger and varied. Polyester, being a less durable compound, is used for making upholstery items, like carpets, bed sheets, pillow covers, tablecloths, curtains, draperies, etc.
It also has insulating properties, that are utilized in the manufacturing of dry suits and mountaineering bags. Epoxy spray paints have low viscosity and high adhesiveness, thus, they are used for painting concrete or filling up minute cracks. Let us see some more difference between the two.

Polyester Resin Vs. Epoxy Resin

➢ Polyester contains an ester functional group, which reacts with an acid to form the condensation product known as polyester resin.

➢ Epoxy is actually a copolymer, wherein two substances form the thermoset compound. These two compounds are the resin (epoxide) and the hardener (polyamine).
➢ Polyester is a stable compound in terms of electrical, chemical, and mechanical properties and is used for making fabric, plastic PET bottles, waterproof covers, etc.

➢ Epoxy's mechanical, electrical, and thermal properties are better, and is also resistant to acidic liquids. It is used to make durable covers for machines and high impact concrete covers.
➢ The curing time for Polyester is much lower, and it is also weaker as it lacks proper binding capacity.

➢The curing time for Epoxy is much higher, and it has a greater binding property, making it stronger.
➢ Polyester finds application in processes like seaming, repairing, laminating, etc., as it is much less durable.

➢ Epoxy is a highly durable compound having a wide range applications, especially in the marine industry. When added to aerospace materials, carbon compounds, and glass materials, it strengthens them.
➢ The adhesive power (100 p.s.i.), or the bonding capacity of Polyester resin is very poor, while it has the highest water absorption capacity. It gets bonded only with fiberglass.

➢ Epoxy has a high bonding capacity (2,000 p.s.i.), and it can adhere to even pre-cured and dissimilar matter. It has a poor water retention capacity