Polyester resins thermal properties

Uses. Neopentyl glycol is used extensively as a chemical intermediate in the manufacture of polyester resins (see Alkyd resins), polyurethane polyols (see Urethane polymers), synthetic lubricants, polymeric plasticizers (qv), and other polymers. It imparts a combination of desirable properties to properly formulated esterification products, including low color, good weathering and chemical resistance, and improved thermal and hydrolytic stabiUty. 

Other minor raw materials are used for specific needs. Eumaric acid [110-17-8] the geometric isomer of maleic acid, is selected to maximize thermal or corrosion performance and is the sole acid esterified with bisphenol A diol derivatives to obtain optimum polymer performance. CycloaUphatics such as hydrogenated bisphenol A (HBPA) and cyclohexanedimethanol (CHDM) are used in selective formulations for electrical apphcations. TetrahydrophthaUc anhydride [85-43-8] (THPA) can be used to improve resiUence and impart useful air-drying properties to polyester resins intended for coating or lining apphcations. 

Resins based on phthaHc anhydride are termed orthophthalic polyesters, and resins based on isophthaHc acid are isophthaHc polyesters. The most commonly encountered resins are the orthophthaHc polyesters, because the isophthaHc polyesters, although offering improved mechanical and thermal properties, are higher in cost. Resins based on terephthaHc acid [100-21-0] improve upon the property set of isophthaHc polyesters, but are very uncommon owing to higher cost. 

A further approach is used by Bayer with their polyesteramide BAK resins. A film grade, with mechanical and thermal properties similar to those of polyethylene is marketed as BAK 1095. Based on caprolactam, adipic acid and butane diol it may be considered as a nylon 6-co-polyester. An injection moulding grade, BAK 2195, with a higher melting point and faster crystallisation is referred to as a nylon 66-co-polyester and thus presumably based on hexamethylene diamine, adipic acid and butane diol. 

Polyurethane mortar flooring systems based on somewhat similar technology to this special polyester system have also been used in chemical plants and have given excellent service. The basic urethane polymer is more elastomeric than either epoxy or polyester resins and, as such, is reported to have excellent thermal properties up... 

PET, PTT, and PBT have similar molecular structure and general properties and find similar applications as engineering thermoplastic polymers in fibers, films, and solid-state molding resins. PEN is significantly superior in terms of thermal and mechanical resistance and barrier properties. The thermal properties of aromatic-aliphatic polyesters are summarized in Table 2.6 and are discussed above (Section 2.2.1.1). 

End-use applications for naphthalate-based polyester resins depend on optimizing the balance of properties desired in a specific application. Usually this involves optimizing the orientation process (uni- or bi-axial) with its accompanying crystallinity development. Subsequent heat setting may be included when additional improvements in thermal stability are needed. 

In the early 1990s, at Newtown Square in Pennsylvania, Lyondell Chemical Company developed an interesting alternative to produce unsaturated polyesters. Based on this development, it became possible to produce a series of very flexible UPRs without sacrificing either mechanical or thermal properties. These products also showed good corrosion resistance when compared to conventional UPR resins. 

The most common advanced composites are made of thermosetting resins, such as epoxy polymers (the most popular singlematrix material), polyesters, vinyl esters, polyurethanes, polyimids, cianamids, bismaleimides, silicones, and melamine. Some of the most widely used thermoplastic polymers are polyvinyl chloride (PVC), PPE (poly[phenylene ether]), polypropylene, PEEK (poly [etheretherketone]), and ABS (acrylonitrile-butadiene-styrene). The precise matrix selected for any given product depends primarily on the physical properties desired for that product. Each type of resin has its own characteristic thermal properties (such as melting point... 

Japan s Showa Highpolymers, part of the Showa Denko group, and Korea s SK Chemicals both have small plants producing aliphatic (polybutylene succinate) and aliphatic-aromatic (polybutyrate adipate terephthalate) polyesters. Both firms also offer their resins in the USA. Showa s Bionelle products are used in commodity bags, agricultural films, traffic cones, and industrial trays. Some Bionolle grades are modified with diisocyanate chain extenders to improve stiffness and thermal properties. 

Polymer concretes show excellent mechanical properties and chemical resistance compared with conventional cement concretes. Polymer concretes can be cured quickly by the use of curing agents. Thus, the applications of polymer concretes are being increased. One of the popular polymers for polymer concretes is unsaturated polyester (UPE) resin. The properties of UPE resin can be modified by changing its molecular features. For the synthesis of the resin, phthalic anhydride or isophthalic acid as well as maleic anhydride can be employed to modify the mechanical properties or hydrothermal resistance. Terephthalic acid which is also used for the synthesis of poly ethylene terephthalate (PET) enhances the thermal resistance of the cured UPE resin. However, the synthesis of unsaturated polyester resin from terephthalic acid is difficult. One method to synthesize unsaturated polyester from terephthalic acid is the use of recycled PET. 

Various UPE resins based on recycled poly ethylene terephthalate(PET) were prepared and the properties of the polymer mortar made with the UPE as well as those of the cured resin itself were investigated. It was found that degree of unsaturation of the resins was the most important property affecting thermal and mechanical properties of the cured resin and PM. The cured unsaturated polyester resin or polymer mortar made from resins of higher unsaturation, i.e., less PET content or adipic acid content in the resin, showed higher glass transition temperatures,... 

Poly(ester-imide) resins have excellent thermal and mechanical properties, and wire enamels made from them are used in stressed electrical appliances. Other uses for imide modified polyesters are also known, where a balance between two thermal properties, cut through and soldering temperature, is required, e.g., in solderable poly(ester-imide)s and poly(ester-imide)s used in polyurethane wire enamels. A third application is in selfbonding wire enamels, where a softening of the film in a given temperature range is desired. 

Figure 3.10 Effect of adventitious moisture on the generation of thermal strain in a polyester resin based cross-ply GRP, postcured at 130°C. The continuous line represents experimental data calculated from the continuous monitoring of the curvature of an unbalanced, as-manufactured beam. The predicted values are calculated from dry (O) and wet ( ) (0.15%) laminate properties using equation [3.12] [25]...

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