Polycarbonate toughness

Within these temperature ranges the polymers are, like the polycarbonates, tough. Because of the stiff chain and the resultant high Tg, processing temperatures need to be above 300°C. 

Polycarbonate Tough, rigid, transparent. Good dimensional stability, high resistance to impact loads. 

Polycarbonate—polyester blends were introduced in 1980, and have steadily increased sales to a volume of about 70,000 t. This blend, which is used on exterior parts for the automotive industry, accounting for 85% of the volume, combines the toughness and impact strength of polycarbonate with the crystallinity and inherent solvent resistance of PBT, PET, and other polyesters. Although not quite miscible, polycarbonate and PBT form a fine-grained blend, which upon analysis shows the glass-transition temperature of the polycarbonate and the melting point of the polyester. 

ABS can be blended with bisphenol A polycarbonate resins to make a material having excellent low temperature toughness. The most important apphcation of this blend is for automotive body panels. 

Polycarbonates. Polyarjiates are aromatic polyesters commonly prepared from aromatic dicarboxylic acids and diphenols. One of the most important polyarylates is polycarbonate, a polyester of carbonic acid. Polycarbonate composite is extensively used in the automotive industry because the resin is a tough, corrosion-resistant material. Polycarbonates (qv) can be prepared from aUphatic or aromatic materials by two routes reaction of a dihydroxy compound with phosgene accompanied by Hberation ofHCl(eq. 5) ... 

PBT is produced by the transesterification of dimethyl terephthalate with 1,4-butanediol by means of a catalyzed melt polycondensation (19). PBT is also semicrystalline and is an extremely tough resin. Several commercial resins use a blend of PBT with another resin, such as PET, polycarbonate, or nylon. Typically, composites of PBT contain 20—30 vol % fiber glass. 

Bromine compounds are often used as flame retardant additives but 15-20ptsphr may be required. This is not only expensive but such large levels lead to a serious loss of toughness. Of the bromine compounds, octabromo-diphenyl ether has been particularly widely used. However, recent concern about the possibility of toxic decomposition products and the difficulty of finding alternative flame retarders for ABS has led to the loss of ABS in some markets where fire retardance is important. Some of this market has been taken up by ABS/PVC and ASA/PVC blends and some by systems based on ABS or ASA (see Section 16.9) with polycarbonates. Better levels of toughness may be achieved by the use of ABS/PVC blends but the presence of the PVC lowers the processing stability. 

Although the nylons are not generally considered as outstanding electrical insulators, their toughness and, to some extent, their temperature resistance, have led to applications in coil formers and terminal blocks. Indeed, the new nylon 46 materials would appear to be of particular interest here. Acetal resins, polysulphones, modified PPO and polycarbonates, however, present a challenge to applications in this sphere. 

The transparent polyamides have increased significantly in importance in recent years. For transparent applications they are competitive with poly(methyl methacrylate), polycarbonates, polysulphones and MBS. In terms of toughness they are like polycarbonates, polysulphones and MBS and much better than the... 

Although the general electrical properties of the polycarbonates are less impressive than those observed with polyethylene they are more than adequate for many purposes. These properties, coupled with the heat and flame resistance, transparency and toughness, have led to the extensive use of these resins in electrical applications. 

The toughness and transparency of polycarbonates has also led to a number of other industrial applications. In Great Britain one of the first established uses was for compressed air lubricator bowls. In the first five years of commercial... 

Block copolymers of polycarbonates and silicone polymers have also been commercially marketed (e.g. Makrolons KU 1-1198 and KU 1-1207). These block copolymers show a marked increase in toughness at low temperatures coupled with reduced notch sensitivity. (They show little improvement in toughness at normal ambient temperatures.)... 

The use of PBT as an engineering material is more a consequence of a balance of good properties rather than of a few outstanding ones. It does not possess the toughness of polycarbonate, the abrasion resistance of an aliphatic polyamide, the heat resistance of a polysulphone, polyketone or poly(phenylene sulphide) or... 

ABS has a specific gravity of 1.03 to 1.06 and a tensile strength in the range of 6 to 7.5 X 10 psi. These polymers are tough plastics with outstanding mechanical properties. A wide variety of ABS modifications are available with heat resistance comparable to or better than polysulfones and polycarbonates (noted later in this section). Another outstanding property of ABS is its ability to be alloyed with other thermoplastics for improved properties. For example, ABS is alloyed with rigid PVC for a product with better flame resistance. 

Polycarbonates and polysuipbones These are tough materials with heat resistance better than most thermoplastics. They are resistant to attack by acids and alcohols but the polycarbonates are sensitive to alkalis. 

Polycarbonate It is a tough, transparent plastic that offers resistance to bullets and thrown projectiles in glazing for vehicles, buildings, and security installations. It with stands boiling water, but is less resistant to weather and scratching than acrylics. It is notch-sensitive and has poor solvent resistance in stressed molded products. Use includes coffee makers, food blenders, automobile lenses, safety helmets, lenses, and many nonburning electrical applications. 

Epoxy resins for printed circuits, castings, rocket motor casings, coatings, and adhesives are almost all made from bisphenol A. Polycarbonates based on bisphenol A are used in glazing applications such as aircraft windows, school windows, and other areas where a combination of toughness and high clarity are required. 

Poly (iminocarbonates) are little known polymers that, in a formal sense, are derived from polycarbonates by the replacement of the carbonyl oxygen by an imino group (Fig. 5). This backbone modification dramatically increases the hydrolytic lability of the backbone, without appreciably affecting the physicomechanical properties of the polymer the mechanical strength and toughness of thin,... 

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