Polyunsaturated elastomers

Stabilization of Elastomers. Polyunsaturated elastomers are sensitive to oxidation. Stabili2ers are added to the elastomers prior to vulcani2ation to protect the mbber during drying and storage. Nonstaining antioxidants such as butylated hydroxytoluene (1),... 

NqV -bis(l-methylheptyl)-p-phenylene-diamine. C6H4[NHCH(CH3)C6H,3]2. Properties Dark reddish-brown liquid. D approximately 0.90 at (26.6C), wt/gal 7.5 lb. Combustible. Use Antiozonant in polyunsaturated elastomers. 

Uses Antioxidant for polyunsaturated elastomers antiozonant for NR, IR, BR, SBR Manuf./Distrib. ChemService http //WWW. chemservice. com] Crompton/Uniroyal... 

Elastomers. Polyunsaturated elastomers are sensitive to oxidation. Stabilizers are added to the elastomers prior to vulcanization to protect the rubber during drying and storage. Nonstaining antioxidants such as buty-lated hydroxytoluene (1), 2,4-bis(octylthiomethyl)-6-methylphenol [110553-27-0], 4,4 -bis(a, a -dimethylbenzyl)diphenylamine (14), or aphosphite such as tris(nonyl-phenyl)phosphite (24) may be used in concentrations ranging from 0.01 to 0.5%. 

A distinction is sometimes drawn between biodegradable and non-biodegradable polymers, but the above arguments indicate that the difference lies in the rates of the abiotic processes which precede biological attack. For example, the polyunsaturated elastomers are very susceptible to biodegradation in the form of latex. This is because the hydrocarbon structure is extremely readily oxidized by oxygen of the atmosphere to low molecular... 

The idea of using polyunsaturated monomers is rooted in the eady history of acryUc elastomers. The first monomers used were butadiene [106-99-0] (35), isoprene [78-79-5] (36), and aHyl maleate [999-21-3] (37), but they did not find commercial success because during polymerization large portions of polymer were cross-linked. Other monomers have been proposed more recentiy tetrahydrobenzyl acrylate (38), dicyclopentenyl acrylate [2542-30-2] (39), and 5-ethyhdene-2-norbomene [16219-75-3] (40). The market potential, at least for the more recent ones, is stiU to be determined. 

Polymers Unsaturated fatty-acid chains offer opportunities for polymerisation that can be exploited to develop uses in surface coatings and plastics manufacturing. Polyunsaturated fatty acids can be dimerised to produce feedstocks for polyamide resin (nylon) production. Work is also ongoing to develop polyurethanes from vegetable oils through manipulation of functionality in the fatty-acid chains, to produce both rigid foams and elastomers with applications in seals, adhesives and moulded flexible parts (see Chapter 5 for more information). 

Natural rubber consists of polyterpenes. The gross formula of this basic elastomer in natural rubber is (CsHgln. The module is isoprene (the base of all terpenoides). It is a polyunsaturated polymer with a structure as shown in... 

ROMP of mono- or polyunsaturated monocyclic alkenes provides linear polymers containing unsaturation at regular intervals along the backbone, termed polyalkenamers (Scheme 4). The properties of these elastomers depend on the degree of unsaturation (as dictated by the monomer) and the cisitrans olefin ratio (as determined by the polymerization... 

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