Rubber-degrading organisms

An in-line moulding press interfaced to a GC-MS has been used to analyse the effluent from the vulcanisation of rubber formulations for the purpose of identifying and quantifying organic compounds present in the vulcanisation fumes [42]. Analyses were performed on natural, ethylene-propylene-diene monomer, styrene-butadiene, nitrile, chloroprene, silicone, and polyfluorocarbon rubbers. Degradation mechanisms were proposed based on the volatiles observed. 

Previous reports 13] emphasized the importance of sample handling, and indeed because of the very volatile nature of the compounds measured in this type of analysis, sample collection deserves special consideration. In general, narrow mouth glass vials with a total volume in excess of 50 ml are acceptable. The bottles need not be rinsed or cleaned with organic solvents, but simply cleaned with detergent and water, rinsed with distilled water, air dried, and dried in a 105°C oven for one hour. The vials are carefully filled with sample to overflowing (zero head space) and a Teflon faced silicone rubber septum is placed Teflon face down on the water sample surface. The septa may be cleaned in the same manner as the vials, but should not be heated more than one hour because the silicone layer slowly degrades at 105°C. 

In the modern urban atmosphere, 03 may be the pollutant of particular concern for health. However, it is a reactive gas that will also attack the double bonds of organic molecules (see Section 2.7) very readily. Rubber is a polymeric material with many double bonds, so it is degraded and cracked by 03. Tyres and windscreen wiper blades are especially vulnerable to oxidants, although newer synthetic rubbers have double bonds protected by other chemical groups, which can make them more resistant to damage by 03. 

In general the nitroso rubbers also suffer from a poor resistance to ionising radiation, sensitivity to degradation by organic bases, highly toxic degradation products and an exceptionally high cost. The advent of the rubbers based on perfluoro(methyl vinyl ether) considered above and of the phosphonitrilic elastomers considered below would appear to put the commercial future of these materials in extreme doubt. 

BQDI 53 is the principal product of both sacrificial and depleting transformations of PD in model hydrocarbons, PO and rubbers and is formed via oxidation with ROO , oxygen, ozone, ozonides, organic peroxides or ions of transition metals. BQDI have therefore been found in PD doped polymers degraded under various conditions [3-5,58]. They are formed in high preparative yield by oxidation with femcyanide and also result in interactions of PD with some rubber chemicals, e.g, with benzothiazolyl-2-sulfenemorpholide. 

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