Engineering plastics toughness

Polyamides (nylon). There are several different types of nylon (e.g. nylon 6, nylon 66, nylon 11) but as a family their characteristics of strength, stiffness and toughness have earned them a reputation as engineering plastics. Table 1.3 compares the relative merits of light metal alloys and nylon. 

Acrylonitrile-butadiene-styrene (ABS). ABS materials have superior strength, stiffness and toughness properties to many plastics and so they are often considered in the category of engineering plastics. They compare favourably with nylon and acetal in many applications and are generally less expensive. However, they are susceptible to chemical attack by chlorinated solvents, esters, ketones, acids and alkalis. 

Plastic also refers to a material that has a physical characteristic such as plasticity and toughness. The general term commodity plastic, engineering plastic, advanced plastic, advanced reinforced plastic, or advanced plastic composite is used to indicate different performance materials. These terms and others will be reviewed latter in this chapter. Plastics are made into specialty products that have developed into major markets. An example is plastic foams that can provide flexibility to rigidity as well as other desired properties (heat and electrical insulation, toughness, filtration, etc.). 

Poly(2,6-dimethyl-l,4-oxyphenylene) (poly(phenylene oxide), PPG) is a material widely used as high-performance engineering plastics, thanks to its excellent chemical and physical properties, e.g., a high 7 (ca. 210°C) and mechanically tough property. PPO was first prepared from 2,6-dimethylphenol monomer using a copper/amine catalyst system. 2,6-Dimethylphenol was also polymerized via HRP catalysis to give a polymer exclusively consisting of 1,4-oxyphenylene unit, while small amounts of Mannich-base and 3,5,3, 5 -tetramethyl-4,4 -diphenoquinone units are always contained in the chemically prepared PPO. 

The fibers made from Nylon 66 are durable, tough, and abrasion-resistant, which suits them for tire cord. They are easy to color, which gives them a secure place in the carpet market (and on the floor). The additional attributes of moldability or processibility make Nylon 66 suitable in the engineering plastics market. 

ABS) terpolymers. These plastics are relatively inexpensive, tough, and durable, and they were the first so-called engineering plastics to capture sizable pipe and auto parts markets. 

Polyolefin (PO) foams are tough, flexible, and resistant to chemical and abrasion however, they are characterized by a low inherent fire resistance and hence quite high amounts of flame-retardants are needed to fulfill fire safety requirements. Therefore, when fire requirements are stringent, generally styrene and engineered plastics are used in spite of polyolefin foams because, for example, for complying UL 94 V-0 rating, 30%-40% fire retardant is normally required for PO foams while only 10%-20% FR additives are required for styrenic foams.91... 

In the case of sPS, the problem of its brittleness can be even more acute since it has to compete with engineering plastics which possess an inherent toughness superior to that of sPS. For this reason, a good impact modification of this product is of paramount importance and may even be essential for its survival as a commercial thermoplastic. For this reason a chapter of this book has been dedicated to the impact modification of sPS using elastomers. Since rubber modification plays such an important role for styrene polymers, whether atactic or sydiotactic, we will first look at the methods of energy dissipation in these homopolymers on impact. 

Both CAP and CAB have superior properties to plain acetate, particularly with reference to toughness and impact strength. Their main uses are as engineering plastics and occasionally for pharmaceutical devices and administration aids. Hard, gas-permeable contact lenses may be made from CAB. 

Acrylonitrile end uses The primary use for acrylonitrile is in the manufacture of polyacrylonitrile (PAN) for acrylic fiber, which finds extensive uses in apparel, household furnishings, and industrial markets and applications, such as carbon fiber. Other end-use markets such as nitrile rubber, styrene-acrylonitrile (SAN) copolymer and acrylonitrile-butadi-ene-styrene (ABS) terpolymers have extensive commercial and industrial applications as tough, durable synthetic rubbers and engineering plastics. Acrylonitrile is also used to manufacture adipinitrile, which is the feedstock used to make Nylon 6,6. 

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