The engineering thermoplastics

The more expensive plastics compete by offering a superior combination of properties to those obtainable from the big four commodity polymers. For transparency and resistance to uv degradation PMMA is outstanding, with polycarbonate as a competitor where there are serious fracture problems. Transparent toughened grades of PMMA have been developed to meet this competition. Polycarbonate offers a unique combination of 

The more expensive plastics compete by offering a superior combination of properties to those obtainable from the big four commodity polymers. For 

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Although ABS resins have a long history by industry standards, the products are anything but mature. ABS resins and blends are, and are expected to remain, the engineering thermoplastics of choice for a wide array of markets. 

Noryl is a rigid dimensionally stable material. Dimensional stabiUty results from a combination of low mold shrinkage, low coefficient of thermal expansion (5.9 x 10 per° C), good creep resistance (0.6—0.8% in 300 h at 13.8 MPa (2000 psi)), and the lowest water absorption rate of any of the engineering thermoplastics (0.07% in 24 h at room temperature). Noryl resins are completely stable to hydrolysis. They are not affected by aqueous acids or bases and have good resistance to some organic solvents, but they are attacked by aromatic or chlorinated aUphatic compounds. 

Nylon (Polyamide) PA is a crystalline plastic and the first and largest consumption of the engineering thermoplastic. This family of TPs are tough, slippery, with good electrical properties, but hygroscopic and with dimensional stability lower than most other engineering types. Also offered in reinforced and filled grades as a moderately priced metal replacement. 

This review is concerned with the engineering thermoplastic uses of polyamide materials in injection moulding and extrusion applications. Types of polyamides are described, and their key properties are considered. Commercial applications in the automotive, electrical/ electronic, engineering and construction, and packaging industries are discussed. Polyamide processing is... 

Figure 2.31 displays the market shares of the most commonly used commodity and engineering thermoplastics in the electrical electronics industry. Only polyamides are identified among the engineering thermoplastics. 

Polyamides and Imides. Nylons. These probably were the first of the engineering thermoplastics, featuring a new combination of... 

CO to give the engineering thermoplastic polyketone, Carilon [45, 46]. Indeed, when a well-defined complex was used (Fig. 7.12), exceptionally high activities were observed [46], with turnover frequencies (TOFs) higher than the conventional catalyst in methanol as solvent. 

The engineering thermoplastics should reach 2,000 million lb in sales by 1988 and will provide an important part of the economic growth of the plastic industry because they are able to compete with metals better than the commodity plastics. Growth and profitability for engineering plastics will continue to be above that of the commodity plastics despite increasing entries. 

The 1950s also saw the development of two families of plastics — acetal and polycarbonates. Together with nylon, phenoxy, polyimide, poly(phenylene oxide), and polysulfone they belong to the group of plastics known as the engineering thermoplastics. They have outstanding impact strength and thermal and dimensional stability — properties that place them in direct competition with more conventional materials like metals. 

PPO has excellent resistance to most aqueous reagents and is unaffected by acids, alkalis, and detergents. The polymer has outstanding hydrolytic stability and has one of the lowest water absorption rates among the engineering thermoplastics. PPO is soluble in aromatic hydrocarbons and chlorinate solvents. Several aliphatic hydrocarbons cause environmental stress cracking. 

Thermoplastic matrix composites have not yet been mentioned much in this review. The hydrophobic (low water absorption) materials such as the polyolefins may be more suitable than thermosets for use in marine apph-cations and have the advantage of low cost. However, many of the engineering thermoplastics, notably polyamides and polyesters, have significant moisture absorption rates. 

Polybutylene terephthalate (PBT) is one of the engineering thermoplastic polyesters that offers excellent performance for a variety of applications. Compounding of PBT with PO provides impact modification depending upon the type of PO used and the suitability of the compatibiliser [22-28]. 

The engineering thermoplastics used are often difficult to bond ... 

There is an increasing need to bond small plastics parts - fans, pulleys, light gears and the like - onto a high quality, finely finished, steel shaft. Because the smooth surface offers little opportunity for mechanical engagement and most of the engineering thermoplastics are difficult to bond, much reduced performance is common. 

The polymers used for injection-moulded gears are selected from the engineering thermoplastics. Those most commonly used are ... 

The general-purpose thermoplastic polymers consist of such materials as polyethylene, polypropylene, polyurethanes, and polyvinyl chlorides. The engineering thermoplastic polymers include the polyimides, polyamideim-ide, polysulfones, polyetheretherketones, and polyphenylene sulfides. 

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