From Properties of Thermoset Plastics

Types of Thermoset Plastics

Thermoset plastics are derived from amorphous polymers. They possess the functional group of polymers through which polymerization and condensation reaction occurs to give a new type of thermoset product.

Thermoset plastics are categorized into phenolic resins, amino resins, polyester resins, silicon resins, epoxy resins, and polyurethanes.

Phenolic Resins or Phenoplasts

Phenolic resins or phenoplasts are products of phenolic derivatives, such as phenol resorcinol, with aldehydes, such as formaldehyde furfural. Example of a phenolic resin is phenol-formaldehyde, also known as bakelite. This resin is prepared by condensing phenol with formaldehyde in the presence of acidic or alkaline catalyst. The initial reaction results in the formation of mono-, di-, and trimethyl 1 phenol, depending on the ratio of phenol to formaldehyde or P/F, type of catalyst, temperature, and time of reaction.

The reaction between methylol phenols and phenols may occur in the following ways:

  • Between the methylol's hydroxyl group and hydrogen in the benzene ring of phenol producing a methylene group.

  • Between the two methylol s hydroxyl groups, forming an ether linkage.

In both the above ways, single water molecule is split off. Further heating produces a linear polymer of varying length, resulting in the following resins:

  • A-stage resin, also called-resol, contains ether linkages composed of a relatively short, low molecular-weight, linear polymer, which is completely soluble in alkaline solution.

  • The B-stage resin, also called resitol, is a rather long, linear-polymer, with a slight amount of cross-linking between chains and is insoluble in the alkaline medium but readily soluble...

Products & Services
Phenolic, Melamine, and Formaldehyde Resins
Phenolic, melamine and formaldehyde resins are thermosetting adhesives that offer strong bonds and good resistance to high temperatures.
Insulating Varnishes and Impregnating Resins
Insulating varnishes and impregnating resins are designed for applications that require a low-viscosity resin or varnish for coil impregnation or magnet wire coating insulation. The resin may infiltrate the coil or electrical device through dipping, trick
Thermosets and Thermoset Resins
Thermosets and thermoset materials are crosslinked polymeric resins that are cured or set using heat or heat and pressure. They generally have a higher resistance to heat than thermoplastics.
Polymer and Plastic Composites
Polymer and plastic composites are strengthened with fibers, fillers, particulates, powders and other matrix reinforcements to provide improved strength and/or stiffness. Examples include fiber reinforced plastics (FRPs), sheet molding compounds (SMCs), bulk molding compounds (BMCs), pre-preg materials, and fabricated composite parts.
Industrial Sealants
Industrial sealants are liquid or viscous compounds used between surfaces to contain fluids, prevent leaks, and prevent infiltration of unwanted material. They may also include compounds for filling gaps or seams.

Topics of Interest

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