Aromatic engineering thermoplastics

The rates of gloss loss and color shift for a series of aromatic engineering thermoplastics, among others, also five ASA samples have been compared at different global sites. Temperature, humidity, rainfall, and acid rain seemed to play minor roles for most polymers (28). 

J. Pickett, M. Gardner, D. Gibson, and S. Rice, Global weathering of aromatic engineering thermoplastics, Polym. Degrad. Stab., 90(3) 405-417, December 2005. 

The effect of irradiation conditions on the degradation of 48 samples across a range of aromatic engineering thermoplastics was studied based on their activation spectra. Using a Xe arc weathering device filtered with CIRA/soda lime filter combinations to irradiate various pigmented polycarbonates, different irradiation intensities were obtained by using different quartz neutral density filter combinations [160]. 

Aromatic polyethers are best characterized by their thermal and chemical stabiUties and mechanical properties. The aromatic portion of the polyether contributes to the thermal stabiUty and mechanical properties, and the ether fiinctionahty faciUtates processing but stiU possesses both oxidative and thermal stabiUty. With these characteristic properties as well as the abiUty to be processed as mol ding materials, many of the aromatic polyethers can be classified as engineering thermoplastics (see Engineering PLASTICS). 

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. 

Commercial engineering thermoplastic nylons are mainly crystalline resins. Nylon-6,6 [32131 -17-2] is the largest volume resin, followed by nylon-6 (48). Other commercially available but much lower volume crystalline nylons are -6,9, -6,10, -6,12, -11, and -12. The crystallinity of the molded part decreases with chain size (49). A few truly amorphous commercial nylon resins contain both aromatic and ahphatic monomer constituents (50). For example, Trogamid T resin is made from a mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamines and terephthahc acid (51). 

Highly aromatic thermoplastic polyesters first beeame available in the 1960s but the original materials were somewhat difficult to process. These were followed in the 1970s by somewhat more processable materials, commonly referred to as polyarylates. More recently there has been considerable activity in liquid crystal polyesters, which are in interest as self-reinforeing heat-resisting engineering thermoplastics. 

Good electrical insulation properties with exceptional tracking resistance for an engineering thermoplastic and, in particular, for an aromatic polymer. In tracking resistance most grades are generally superior to most grades of polycarbonates, modified PPOs, PPS and the polyetherimides. 

Aromatic-aliphatic polyesters, in which either R1 or R2 is aromatic, are generally high-melting (150-270°C) semicrystalline materials that find applications as engineering thermoplastics, films, or fibers. 

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). 

Amorphous engineering thermoplastics, 25 Amorphous partial aromatic polyamides, 139... 

Not all polyetherimides are limited by their tractability, however. Certain aromatic polyetherimides are characterized by a combination of properties that makes them potential engineering thermoplastics (90). One of these polymers contains an isopropylidene unit in the backbone to enhance the solubility. It is a mol ding material introduced by General Electric in 1981 and sold as Ultem resin. Attractive features include high temperature stability, flame resistance without added halogen or phosphoms, high strength, solvent resistance, hydrolytic stability, and injection moldability. 

POLYAMIDE-IMIDE RESINS. An injection-moldable, high-performance engineering thermoplastic, polyamide-imide is the condensation polymer of tnmellitic anhydride and various aromatic diamines with the general structure ... 

An extensive investigation was carried out in our laboratories of an aromatic sulfonate copolyester system, which led to the definition of a remarkable class of engineering thermoplastics. In this chapter we dis-... 

Owing to its partial crystallinity, sPS is strongly resistant to concentrated acid and bases, oils and greases and most organic solvents, except chlorinated and aromatic compounds that cause swelling. Its density (about 1 g/cm3) is significantly low compared with other engineering thermoplastics such as polyamide-6, poly(butylene terephthalate) and poly(phenylene sulfide), and this is... 

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