Nylon amorphous

Amorphous adsorbents Amorphous nylon Amorphous nylons Amorphous polymers... 

The crystallinity can be dismpted by substituents on the chains that interfere with the alignment process. Amorphous nylons are produced by deUberately engineering this effect, eg, nylon-NDT/INDT (also known as PA-6-3-T or PA-TMDT), which uses trimethyl-substituted hexamethylenediamine isomers combined with terephthaUc acid. 

Fig. 1. Chemical stmctures of barrier polymers, (a) Vlaylidene chloride copolymers (b) hydroly2ed ethylene—vinyl acetate (EVOH) (c) acrylonitrile barrier polymers (d) nylon-6 (e) nylon-6,6 (f) amorphous nylon (Selar PA 3426), y = x - - z-, (g) nylon-MXlD6 (h) poly(ethylene terephthalate) and (i) poly(vinyl...

Fig. 1. Engineering resins cost vs annual volume (11) (HDT, °C) A, polyetheretherketone (288) B, polyamideimide (>270) C, polyarylether sulfone (170- >200) D, polyimide (190) E, amorphous nylons (124) F, poly(phenylene sulfide) (>260) G, polyarylates (170) H, crystalline nylons (90—220) I, polycarbonate (130) J, midrange poly(phenylene oxide) alloy (107—150) K, polyphthalate esters (180—260) and L, acetal resins (110—140).

Amorphous nylons are transparent. Heat-deflection temperatures are lower than those of filled crystalline nylon resins, and melt flow is stiffer hence, they are more difficult to process. Mold shrinkage is lower and they absorb less water. Warpage is reduced and dimensional stabiUty less of a problem than with crystalline products. Chemical and hydrolytic stabiUty are excellent. Amorphous nylons can be made by using monomer combinations that result in highly asymmetric stmctures which crystalline with difficulty or by adding crystallization inhibitors to crystalline resins such as nylon-6 (61). 

Over 565,000 t/yr of nonftber crystalline nylons is sold worldwide (63). Since markets are controUed by the economy, a modest growth of 5—8%/yr is expected. Although currently only ca 900 t/yr of amorphous nylons is sold worldwide (64), a growth rate of 10% is expected because of increased research activity. Currently, the amorphous nylon resins compete with PEI and polyesters in many appHcations. 

The PEEK resia is marketed as aeat or filled pellets for iajectioa mol ding, as powder for coatiags, or as preimpregaated fiber sheet and tapes. Apphcations iaclude parts that are exposed to high temperature, radiation, or aggressive chemical environments. Aerospace and military uses are prominent. At present, polyamideimide (PAl) resia and poly(arylene sulfides) are the main competitors for apphcations requiring service temperatures of 280°C. At lower temperatures, polyethersulfones, amorphous nylons, and polyetherimides (PEI) can be considered. 

Liquid-crystal (79), advanced polyimide, and amorphous-nylon resin technologies (60) will be appHed. 

Amorphous graphite, 12 784-785, 793 Amorphous nylon (Selar PA 3426) as good barrier-to-permanent gases, 3 384, 385... 

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