Polyamides, additives Antioxidants

Fig. 76. Curves of the increase in pressure in the oxidation of polyformaldehyde (200°C, Pog = 200 mm Hg) without additions (1) and with additions of polyamide (2), antioxidant (3), and a mixture of them (4).

Experiments we conducted have shown that the addition of a polyamide alone or an inhibitor alone is relatively ineffective, somewhat reducing the gas evolution in the oxidation of polyformaldehyde. Only the joint introduction of a polyamide and an inhibitor proves far more effective than the introduction of the polyamide and antioxidant individually (Fig. 76). The effectiveness of the inhibitor was evaluated in [22] according to the amount and rate of gas evolution in the thermooxidative destruction of polyformaldehyde [18] on a static setup. 

Monofunctional, cyclohexylamine is used as a polyamide polymerization chain terminator to control polymer molecular weight. 3,3,5-Trimethylcyclohexylamines ate usehil fuel additives, corrosion inhibitors, and biocides (50). Dicyclohexylamine has direct uses as a solvent for cephalosporin antibiotic production, as a corrosion inhibitor, and as a fuel oil additive, in addition to serving as an organic intermediate. Cycloahphatic tertiary amines are used as urethane catalysts (72). Dimethylcyclohexylarnine (DMCHA) is marketed by Air Products as POLYCAT 8 for pour-in-place rigid insulating foam. Methyldicyclohexylamine is POLYCAT 12 used for flexible slabstock and molded foam. DM CHA is also sold as a fuel oil additive, which acts as an antioxidant. StericaHy hindered secondary cycloahphatic amines, specifically dicyclohexylamine, effectively catalyze polycarbonate polymerization (73). 

LTDP is a thiosynergist antioxidant additive to thermo/light-stabilizers (used in combination with phenolic antioxidants) with plasticizing properties used to decompose and neutralize hydroperoxides, formed by the auto-oxidation of polymers, primarily in PE, PP, ABS, polyester, and polyamide. 

For quality control reasons, rapid screening methods are needed to identify the volatiles in polymeric materials collected for recycling. HS-SPME-GC-MS was shown to be a fast and sensitive method to screen for brominated flame retardants in recycled polyamide materials [78]. HS-SPME effectively extracted several brominated compounds, all possible degradation products from the common flame-retardant Tetrabromobisphenol A from recycled polyamide 6.6. Furthermore, the high extraction capacity of the PDMS/DVB stationary phase towards aromatic compounds was demonstrated, as the HS-SPME-GC-MS method allowed the extraction and iden-tiflcation of brominated benzenes, from a complex matrix only containing trace amounts of analytes. In addition, degradation products from an antioxidant, a hindered phenol, were extracted. Figure 14 shows a typical chro-... 

In practice, the choice of WI is based on the analysis of service, design, economic and other factors. An efficient means of improving wear resistance of the polyamide-steel 45 friction pair turns out to be inhibition of the thermally oxidative and destructive processes in the polymer surface layers to avoid the formation of corrosion-active oxide compounds. It is possible to break this unfavorable cycle by the introduction of antioxidants into the polymer composition, thus disabling macroradicals through the reactions of mechanochemical synthesis, polyamide alloying by functional additives forming separating layers or more thermally stable products, and so on [108]. Application of WI with this aim abates undesirable thermally oxidative processes in polyamide... 

Thermal degradation of polyoxymethylene and polyacetals results in the formation of formaldehyde, which is furthermore catalyzed by oxidation of formaldehyde to formic acid. In addition to antioxidants and acid scavengers, formaldehyde scavengers are used in polyacetal formulations. Formaldehyde scavengers of choice are nitrogen compounds, for example, melamine derivatives such as benzoguanamine, urea derivatives such as allantoin, hydrazides, imides, and polyamide. 

NFPA Health 3, Flammability 1, Reactivity 0 Uses Curing agent for cast PU elastomers, food-contact PU resins epoxy resin curing/hardening agent corrosion inhibitor intermediate for paints, dyes, polymers isocyanate resins polyamides determination of tungsten and sulfates curing system additive for bisphenol A-ep-ichlorohydrin epoxies for food contact antioxidant in food-contact rubber articles for repeated use... 

Uses Antioxidant stabilizer for styrenics, polyolefins, polyamide, PVC, urethane and acrylic coatings, adhesives, elastomers, cellulosics metal deactivator replaces BHT in polyolefins antioxidant, stabilizer in food-grade polymers, acrylic food pkg. in food-pkg. adhesives Regulatory FDA 21CFR 175.105,177.1010,178.2010 Manuf./Distrib. Aldrich Allchem Ind. ChemService Ciba Spec. Chems./ Addit. GE Spec. 

Toxicology LD50 (oral, rat) 6300 mg/kg TSCA listed Uses Antioxidant/stabilizer for polyolefins, polyamides, PU, PVC, PS, rubbers, cellulosics, food-grade polymers, food-pkg. adhesives antioxidant in lubricants for incidental food-contact use metal deactivator Regulatay FDA 21CFR 175.105,178.2010,178.3570 Manuf./Distrib. Ciba Spec. Chems./Addit. 

Synonyms N,N -Bis (3,5-di-t-butyl-4-hydroxyhydrocinnamoyl) hydrazine Uses Antioxidant for polyolefins, polyesters, polyamides, PVC, PS, rubbers, cellulosics antioxidant/stabilizer for food-grade polymers in food-pkg. adhesives Regulatory FDA 21CFR 175.105, 178.2010 Manuf./Distrib. Ciba Spec. Chems./Plastic Addit. http //www.cibasc.com, Fairmount Trade Name Synonyms BNX MD-1024 [Mayzo http //www.mayzo.com], Irganox MD 1024... 

Uses Feed additive nutrient dietary supplement in table salt as source of dietary iodine catalyst in Sandmeyer reactions cloud seeding heat stabilizer for glass fiber-reinforced polyamides antioxidant/stabilizer... 

Uses UV absorber, light stabilizer for plastics, PVC, PP, SBS footwear, SEBS, acetal, acrylic, polyamide, PET, PMMA, PBT, PC antioxidant/stabilizer for food-grade polymers Regulatory FDA 21CFR 178.2010 Trade Name Synonyms Lensorb C448 [Lenape Ind. http //www.ienape.com], Tinuvin 234 [Ciba Spec. Chems./Plastic Addit. 

Uses Processing stabilizer, sec. antioxidant for polymers incl. polyolefins, polyesters, polyamides, ABS, PS, polybutylene, PBT, PVC, nitrile barrier resins, food-contact polymers peroxide decomposer for plastics mfg. Reguiatory FDA cleared as indirect food additive Manuf./Distrib. Clariant http //www.ciariant.com, http //WWW. ciariant-northamerica. com Trade Name Synonyms Alkanox 24-44 [Great Lakes http //www.greatiakeschem. com] Phosphite 1 t[Ciba Spec. Chems./Plastic Addit. http //WWW. cibasc. com]... 

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