When was polyester resin invented

The first use of glass fibre reinforced polyester composites was in aircraft ducting, with the first non-military application in boat hulls. The invention of the pultrusion line allowed development of unsaturated polyester based materials into new application areas such as oil wells, fishing rods and electrical insulation devices.

The filament winding process further expanded the potential market for unsaturated polyester resins. These products may be generically referred to as PMCs polyester moulding compounds. Compounds of this type contain chopped glass fibres and resin, they offer the advantage that, during formation, fibres and resins are able to flow under the action of heat and pressure in a hot press or compression moulding system.

Systems of this nature facilitate the moulding of complex details from simple material packs. Cycle times tend to be between two and ten minutes. High pressures and tooling costs associated with such processes mean those forming quantities of less than 10, tend not to be economic. The nature of the Unsaturated Polyester means that physical properties are dependant on the additional materials used, and the conditions of curing, for a specific application.

With such variety available it is best to refer to manufacturers for performance of individual grades. Contact Moulding is the dominant UK processing technique for unsaturated polyesters. It can also provide an effective transmission barrier for highly aromatic foods such as coffee. Higher performance blends are available at increased costs, where the tradeoff between cost and performance is less of a consideration and where replacing costlier polyamides might sway any decisions.

PET may be purchased in pellet form for molding and extruding, both as new and as regrind. It is available as in forms which include flexible and semi-rigid film for packaging, sheet-form for thermoforming, and in various extruded shapes such as rounds and bars. Polyester resins are compatible with dilute acids, oils and greases, aliphatic hydrocarbons, and alcohol.

They tolerate dilute alkalis and aromatic and halogenated hydrocarbons to a lesser extent. The material is UV resistant. The crystalline structure of the material is responsible for its generally good chemical resistance. This article presented a brief discussion of polyester PET resins including information on their properties and uses.

For more information on other resins, consult our other guides or visit the Thomas Supplier Discovery Platform to locate potential sources of supply or view details on specific products. Guides Share:. Specific Gravity 1.

A thermoplastic or thermosetting resin made by the reaction of an ester of dihydric alcohol and terephthalic acid. Polyester resins were first discovered by the Swedish chemist Berzelius in Thermosetting polyesters are cross-linked alkyd resins that are used as paints and in molded or cast products.

Thermoplastic polyesters are linear compounds that are used in fibers and films. Whinfield and J. Dickson, in For use in moulding, a polyester resin requires the addition of several ancillary products.

These products are generally:. A manufacturer may supply the resin in its basic form or with any of the above additives already included. As has been mentioned, given enough time an unsaturated polyester resin will set by itself. This rate of polymerisation is too slow for practical purposes and therefore catalysts and accelerators are used to achieve the polymerisation of the resin within a practical time period.

Catalysts are added to the resin system shortly before use to initiate the polymerisation reaction. The catalyst does not take part in the chemical reaction but simply activates the process. It is now a chemically resistant and usually hard solid.

It is a non-reversible chemical reaction. Great care is needed in the preparation of the resin mix prior to moulding. The resin and any additives must be carefully stirred to disperse all the components evenly before the catalyst is added.