Plastics, high-performance, polyesters

Synthetic lubricants are made with neopentyl glycol in the base-stock polyester (24). Excellent thermal stabiHty and viscosity control are imparted to special high performance aviation lubricants by the inclusion of polyester thickening agents made from neopentyl glycol (25,26) (see LUBRICATION AND lubricants). Neopentyl glycol is also used to manufacture polymeric plasticizers that exhibit the improved thermal, hydrolytic, and uv stabiHty necessary for use in some exterior appHcations (27). 

Phthahc anhydride (1) is the commercial form of phthaUc acid (2). The worldwide production capacity for the anhydride was ca 3.5 x 10 metric tons ia 1993, and it was used ia the manufacture of plasticizers (qv), unsaturated polyesters, and alkyd resins (qv) (see Polyesters, unsaturated). Sales of terephthahc acid (3) and its dimethyl ester are by far the largest of any of the benzenepolycarboxyhc acids 14.3 x 10 t were produced in 1993. This is 80% of the total toimage of ah. commercial forms of the benzenepolycarboxyhc acids. Terephthahc acid is used almost exclusively for the manufacture of poly(ethylene terephthalate), which then is formed into textiles, films, containers, and molded articles. Isophthahc acid (4) and trimehitic anhydride (5) are commercial products, but their worldwide production capacities are an order of magnitude smaller than for terephthahc acid and its dimethyl ester. Isophthahc acid is used primarily in the production of unsaturated polyesters and as a comonomer in saturated polyesters. Trimehitic anhydride is used mainly to make esters for high performance poly(vinyl chloride) plasticizers. Trimesic acid (6), pyromehitic dianhydride (7), and hernimehitic acid (8) have specialized commercial apphcations. The rest of the benzenepolycarboxyhc acids are not available commercially. 

Acrylic ESTER POLYMERS Acrylonitrile POLYMERS Cellulose esters). Engineering plastics (qv) such as acetal resins (qv), polyamides (qv), polycarbonate (qv), polyesters (qv), and poly(phenylene sulfide), and advanced materials such as Hquid crystal polymers, polysulfone, and polyetheretherketone are used in high performance appHcations they are processed at higher temperatures than their commodity counterparts (see Polymers containing sulfur). 

Among these dye classes, anthraquiaone dyes are ia an important position ia reactive dyes and vat dyes for cellulose fibers, disperse dyes for polyester, and acid dyes for polyamide. Application for high performance organic pigments for plastics and paints are also important areas. 

In the manufacture of unsaturated polyester resins the polyester is synthesized and then diluted with a vinyl reactive monomer such as styrene (see POLYESTERS, UNSATURATED). A portion of the dibasic acid of the polyester is maleic or some other vinyl reactive diacid that can be polymerized with the styrene to yield a highly cross-linked, high performance polymer system. Other esters made with propylene glycol, dipropylene glycol, and tripropylene glycol are used as emulsifiers in foods, as plasticizers in polymer systems, and as part of acrylate resin systems. 

Specialty polymers achieve very high performance and find limited but critical use in aerospace composites, in electronic industries, as membranes for gas and liquid separations, as fire-retardant textile fabrics for firefighters and race-car drivers, and for biomedical applications (as sutures and surgical implants). The most important class of specialty plastics is polyimides. Other specialty polymers include polyetherimide, poly(amide-imide), polybismaleimides, ionic polymers, polyphosphazenes, poly(aryl ether ketones), polyarylates and related aromatic polyesters, and ultrahigh-molecular-weight polyethylene (Fig. 14.9). 

JACKSON MORRIS Polyesters for High-Performance Plastics... 

A number of thermotropic polyester-carbonates were prepared through melt-polymerization of substituted hydroquinones and diphenyl tere-phthalate and diphenyl carbonate to have high molecular weight, with reduced viscosity in the range of 2-3. The molecular weights of the polymers can be advanced further by solid state heat-treatment, with the rate of postpolymerization depending on temperature and Concentration of catalyst. Samples of some compositions can be spun into high performance fibers and processed into self-reinforced plastics. The properties of thermotropic polyester-carbonates and polyesters were compared as fibers and plastics. 

The objectives of carrying out solid-state heat-treatments of thermotropic polyester-carbonates were twofold. One, to study the heat-treatment phenomena. Two, to prepare samples of higher molecular weight for processing studies into high performance fibers and plastics if heat-treatment did cause advances in molecular weight. 

The classic thermosets, such as ebonite, phenolics, ureas, melamines and polyesters as well as the epoxies, when reinforced with fiberglass or graphite fibers could also be classified as high performance thermosets. While these plastics cannot be readily extruded or injection molded, they are resistant to the effects of moderately high hostile environments. Phenolic resin mortars have been used for over a half century for the construction of chemical resistant vessels and for joining brick and tile used as linings in hot acid environments. (1.)... 

This improvement in properties need not necessarily result in market sales since unsaturated polyesters are not high performance plastics, and are generally sold in the lowest price markets. However, the cost of adding a few percent of low cost PMEft should be small and there may be no significant price disadvantage. 

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