Epoxy and polyester resins have a different molecular composition and differ in their properties and qualities as well. Epoxies often suit conditions better and offer greater strength, among other desired qualities.
While many people quote “resin” while speaking of an adhesive, they to do not point out which adhesive they are actually talking about. When it comes to adhesives, the two popular resins include the polyester resin and the epoxy resin. These two resins have different characteristics. Knowing more about them will help you find out the best adhesive that suits your application related requirement and scenario.
Epoxy resins are very strong and offer better flexural or bend strengths. This strength may be up to 17500 psi or even more. These resins are composed of either lower molecular weight prepolymers or may be constituted of high molecular weight polymers (containing two epoxide groups or more). The raw material used for their synthesis is often petroleum, while there are plant-derived epoxies also available. Epoxy resin price is quite affordable when you buy it online.
The resins are synthetic in origin and are formed through the reaction that takes place between polyhydric alcohol and dibasic organic acids (mostly maleic anhydride). These resins can also be termed as the condensation polymer. The alcohol can be a polyol, or an inorganic compound having hydroxyl or multiple alcohol functional groups.
Key Differences between Polyester Resins and Epoxies
Here are some of the key and important differences between the two types of adhesives. The information will help you make good decisions when you have to choose between the two.
Bonding Strength: Epoxies have better bonding strength and capability. While the epoxy resin may have the strength of around 2000 lbs. per square inch, the same for polyester resin would be around 500 lbs. per square inch.
Wear Resistance: Epoxies provide for long-term fixation and joining benefits and resist peeling, cracking, wearing, and corrosion better. They can also resist environmental degradation and chemical damage for a longer time period when compared to polyester resins. The polyester resins may be well suited for low-stress applications and for the temporary fixes.
Moisture Resistance: Here again the epoxies emerge out to be the winner. These formulations are effective even underwater. While the polyester resins also offer resistance towards water and moisture, they fracture easily and are more permeable to water.
Accountability: The polyester resins often cost less than the epoxy resins and may be used for jewellery or craft making. The epoxies are stronger, have better fixation capabilities, and also cost more.
Application or Cure Time: The polyester resin provides for faster cure rates. But some epoxy adhesives can also work in extreme temperature situations. Temperature-related manipulations may provide for a change in curing time.
Longevity and Shelf Life: Epoxy is mixed before application. As long as they have not been mixed, they sit on the shelves and racks for long time duration and may be useful for many years. Hence, there is no loss of potency for epoxies even after multiple years of storage. Resins lose their potency over a short time period and hence should be used within the time provided through the instructions. The resin may not be stored for more than 1 year.
Odour: Polyester resins can smell really bad and the fumes emanating out of it can even burn the hair in the nostrils. You may also require good ventilation when you are working with epoxies.
Hence, when you are looking for strong bonds that need to hold their configuration for the long time period, an epoxy adhesive is the right solution. For short-term fixes, you can opt for the resins.