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EPP Knowledge Letter_Sharing the knowledge is the way to immortality_ issue 02

                                           

Thermoset Resin

Thermosetting resins are petrochemical materials that cure irreversibly. Cure can be brought about by heat, chemical reaction or appropriate irradiation. It is used as an adhesive as well as in semiconductors and integrated circuits.

Thermosetting resins are popular because they are uncured and in a liquid state at room temperature.

This allows for convenient impregnation of reinforcing fibers such as fiberglass/carbon fiber or Kevlar. A thermosetting resin is also known as a thermoset.

Thermosetting resins are rigid polymeric materials that are resistant to higher temperatures than common thermoplastics. These materials are usually composed of lines of polymers, which are highly cross-linked.

The heavily cross-linked structure produced by chemical bonds in thermoset materials is directly responsible for the higher mechanical and physical strength compared to thermoplastics or elastomers. However, it offers poor elasticity or elongation of the material, once hardened, the thermoset resin cannot be reheated and melted to shape differently.

The cross-linking process eliminates the risk of remelting the product when heat is applied, making thermosets ideal for high-heat applications such as chemical processing, electronics and appliances. Since their shape is permanent, they cannot be recycled as a source of newly made plastic.

Common thermosetting resins include:

Polyester Resin : 

For FRP production, polyester is an advantageous, general-purpose thermoset resin.

It is generally available as isophthalic polyester (premium polyester) or orthophthalic (general purpose).

Orthophthalic polyester resins offer average water resistance and selectivity to common chemicals. Isophthalic thermosets are preferred for applications where corrosion is more aggressive.

All these resins are used for fiberglass linings, coatings, and molds include pond linings, storage tanks, pipes, automotive components, and marine components (e.g. boat and yacht hulls and decks) as well as fiberglass roofing materials, fiberglass roof repair kits, and more commonly, but they not limited to that. Repair kits. It is also used as an ingredient in specialty coatings and adhesives. Despite this, they are often surpassed by vinyl ester thermoset resins when long-term structural integrity is required.

Vinyl ester Resin:
A custom thermoset solution, vinyl ester resin is produced by esterification of a suitable epoxy with acrylic or methacrylic acid (MMA). It offers enhanced long-term mechanical performance compared to polyester thermoset resins and reduced cost when compared to pure epoxy. It offers superior resistance to moisture penetration and superior anti-corrosion properties compared to GP polyester [2]. Consequently, vinyl ester resins are suitable for use in corrosion-resistant industrial tanks and pipes and pultruded profiles. Additionally, vinyl esters are often used in critical components of automotive and marine vehicles.

Epoxy Resin:
Epoxies are the most preferred thermoset resins for their superior thermal and mechanical properties under curing conditions. The thermochemical integrity of standard epoxies is so great that they are often used to reinforce and bond FRP components, as well as to seal the cut ends of machined parts to minimize chemical intrusion. MMA (methacrylic acid) can be used by itself for proprietary applications. However, the resin is commonly used as a precursor to polymethyl methacrylate (PMMA) or as an epoxy-admixture in customized thermoset resin mixtures [2]. Epoxy resins are used for high pressure and temperature application, coating, adhesion, and repairs.

Phenolic Resin:
Phenolic resins are synthetic polymers that are partially synthesized from formaldehyde. This justifies their excellent flame-retardancy and low smoke emission capabilities, giving FRP manufacturers the best fire-resistant properties of all standard thermoset resins available [2]. Phenolic resins are good for high-temperature applications where parts must meet fire safety standards. Phenolic resins are used in a wide range of applications including offshore water pipe systems, electronics, ballistics, mine ventilation, aerospace, rail and mass transit.


Source :  Content based on collections of information from public domain

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