Acrylonitrile discoloration

Allen DS, Birchmeier M, Pribish JR, Priddy DB and Smith PB (1993) Thermal styrene-co-acrylonitrile discoloration problem the role of sequence distribution and oligomers. Macromolecules 26 6068-6075. 

Diarylamiaes fuactioa as mbber antioxidants by breaking the peroxidative chain reactions leading to mbber deterioration. Nearly all commercial synthetic mbbers (see Elastomers, synthetic), including neoprene, butyl, styrene—butadiene, and the acrylonitrile—butadiene mbbers, can be protected with about 1—2% of an alkylated diphenylamine. DPA itself is not used as a mbber antioxidant. An objectionable feature of these antioxidants is that they cause discoloration and staining which limits their use to applications where this is not important. 

Priddy, X), R Thermal Discoloration Chemistry of Sty rene-oo-Acrylonitrile. VoL 121, pp, 123-154. 

To control compatibility and other properties of butadiene/acrylonitrile copolymers with PVC, there is an optimum acrylonitrile content of 37%. For practical handling, the nitrile rubber is treated on rolls at normal temperatures, and afterwards the mixture is rolled with PVC at elevated temperatures. The reverse process—plasticizing PVC first and mixing with nitrile rubber afterwards—is not so favorable because discoloring and decomposition may occur. This can be avoided by simultaneously applying the liquid plasticizers. Nitrile content in-... 

Further evidence of the heat stability of the PTHF blends with PVC and CPVC was obtained in an oven aging test at 350°F. Samples were removed from the oven at 10-minute intervals and compared with similarly treated blends containing the impact modifier, a styrene/acrylonitrile/butadiene terpolymer. The blends containing PTHF were outstanding in their resistance to discoloration at elevated temperature. The blends containing the terpolymer showed some darkening at 90 minutes and were brown at 370 minutes. The PTHF blends did not discolor at all until 190 minutes, and 920 minutes were required for the... 

Priddy,D. B. Thermal Discoloration Chemistry of Styrene-co-Acrylonitrile.Vol. 121,pp. 123-154. 

Pure acrylonitrile may polymerize at room temperature to polyacrylonitrile (PAN), a compound that, unlike polyamides and polyesters, does not melt at elevated temperatures but only softens and finally discolors and decomposes. Nor is it soluble in inexpensive low-boiling organic solvents. Because fibers made from it resist the dyeing operations commonly used in the textile industry, the usual practice is to modify it by copolymerization with other monomers, for example, vinyl acetate, styrene, acrylic esters, acrylamide, or vinyl pyridine in amounts up to 15 percent of the total weight (beyond which the final product may not be termed an acrylic fiber). The choice of modifier depends on the characteristics that a given manufacturer considers important in a fiber, the availability and cost of the raw materials in the manufacturer s particular area of production, and the patent situation. 

Priddy DB (1995) Thermal discoloration chemistry of styrene-co-acrylonitrile. Adv Polym Sci 121 123-54. 

Priddy, D. B. Thermal Discoloration Chemistry of Styrene-co-Acrylonitrile. Vol. 121, pp. 123-154. Privalko, V. P. and Novikov, V. V.Model Treatments of the Heat Conductivity of Heterogeneous Polymers.Vol. 119, pp 31-78. 

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