Isophthalic Polyesters

These polyester resins use isophthalic acid in place of phthalic anhydride as the saturated monomer. This increases the cost to produce, but it improves physical properties and corrosion resistance. 

The standard corrosion grade isophthalic polyesters are made with 1 1 molar ratio of isophthalic acid to maleic anhydride or fumaric acid with propylene glycol. In general, the properties of isophthalic polyesters are superior to the lower-cost general purpose polyesters, not only in chemical resistance but also in physical properties. They can be formulated to be fire retardant or to protect against the effects of ultraviolet light. 

Isophthalic polyesters have a relatively wide range of corrosion resistance. They are satisfactory for use up to IZST (52 C) in adds such as 10% acetic, benzoic, boric, citric, oleic, 25% phosphoric, tartaric, 10-25% sulfuric, and fatty acids. 

Most organic salts are also compatible with isophthalic polyesters. Solvents such as amyl alcohols, ethylene glycol, formaldehyde, gasoline, kerosine, and naphtha are also compatible. 

The isophthalic polyester resins are not resistant to acetone, amyl acetate, benzene, carbon disulfide, solutions of alkaline, salts of potassium and sodium, hot distilled water, or higher concentrations of oxidizing acids. 

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The results described in this paper were all obtained from tests on E-glass reinforced composite materials produced by hand lay-up. This is the manufacturing route most frequently used for marine structures. For the majority of the tests reported here the E-glass fibres were either quasi-unidirectional (250 g/m with 1 g/m of polyester fibres bonded in the 90° direction to keep the UD fibres in place) or stitched quadrlaxial (0/45/907-45° 1034 g/m ) cloths. The same uniaxial ply is used in both cloths. The resin is based on DGEBA epoxy (SRI500) with an amine hardener (2505) from Sicomin, France. All epoxy specimens were post-cured at 90°C for 6 hours. Some results are also shown for a woven glass (0/90° 500 g/m ) reinforced isophthalic polyester for comparison, as this is the traditional marine... 

Dion-Iso . [ReichholcQ Isophthalic polyester resin resin for transportation, marine, elec., and corrosion control applies. for sprayup/layup, filament winding, moldings. 

Two-component, polyol-cured 25.4 6 Isophthalic polyester (vinyl toluene ... 

A work targeted specifically to civil infrastructure application has reported mechanical data on freeze-thaw tests conducted on isophthalic polyester and vinyl ester pultruded/glass fiber RPs (Chapter 3). Specimens were aged in accordance with ASTM C666 (namely, 40F to OF followed by a hold at OF and a ramp up to 40F followed by a hold) while submerged in 2% sodium chloride and water. Specimens were removed after every 50 cycles and tested in ASTM 3-point flexure mode. The results clearly indicated a reduction in flexure strength and modulus after 300 cycles. 

Refer to Table 3.7 for the compatibility of isophthalic polyester with selected corrodents. Reference [1] provides a more comprehensive listing. 

Compatibility of Isophthalic Polyester with Selected Corrodents... 

Isophthalic polyesters provide corrosion resistance in a wide variety of end uses. Recent excavations of 25-year-old FRP underground gasoline storage tanks offer evidence to the resin s resistance to internal chemical attack or external attack by water in the siuroimding soil. Isopolyester pipes and containment vaults also provide protection against failme from corrosion by acid media. Reference [2] provides information on FRP piping systems. 

The bisphenol polyesters are superior in their corrosion resistant properties to the isophthalic polyesters. They exhibit good performance with moderate alkaline solutions of bleaching agents. The bisphenol polyesters will break down in highly concentrated acids or alkalies. These resins can be used in the handling of the following materials ... 

Terephthalate polyesters are based on terephthalic acid, the para isomer of phthalic acid. The properties of cured terephthalic-based polyesters are similar to those of isophthalic polyesters, with the terephthalics having higher heat distortion temperatures and being somewhat softer at equal saturation levels. 

Isophthalate Polyester An unsaturated polyester based on isophthalic acid. 

Processors fabricate underground fuel storage tank by combining isopolyester resin with fiberglass and surfacing veils on a cylindrical mandrel. Since 1964, almost 350000 isophthalic polyester tanks have been buried under service stations around the United States, according to the Fiberglass Petroleum Tank and Pipe Institute. 

Table 8.3 Properties of unearthed FRP tanks (isophthalic polyester resin SG-10, described in bulletin IP-86 ) with glass reinforcement. Values are averages of several samples...

In 1971, one of the first pipes was installed in the UK in London in the form of 1.17 X 0.61 m egg shaped profiles. A polyester felt mat tube impregnated with an isophthalic polyester resin was installed and cured in place. After 20 years, a section of the pipe was taken out of service and the strength properties were measured. The cured-in-place pipe retained its properties and still had a flexural strength that was 30% over the initial installation requirements. The parts showed no sign of wear or deformation. Several other pipe sections have been checked after years of service and found to be virtually unchanged. 

Uses Esterification catalyst for mfg. of unsaf. polyesters, esp. isophthalates, polyester polyols, phthalates, adipates, powd. coatings, coil coatings, specialty enamels at temps, of 200-230 C Properties Wh. solid sol. in most ester prods. insol. in most org. soivs. ... 

Chem. Descrip. Pigment disps. in hydroxyl functional isophthalic polyester resin... 

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