Vulcanization fume

Fig. 11. Direct analysis of vulcanization fume using the gas transfer mould operating on-line a Finnigan 1020 automated GC/MS. The mass spectrometer has the capability to provide diagnostic spectra on component quantities of ljug or less. These components are separated for analysis by the gas chromatograph which in tMs installation is a Perkin-Elmer Sigma 3 and is directly behind the GTM. (Reproduced by courtesy of Rapra Technology Ltd,...

The trimer of isobutylene merits special mention, for it has been found to be one of the most abundant species in vulcanization fume from elastomers not derived from isobutylene as a monomer. This effect was first explained in 1981 from the results of laboratory vulcanizations at Rapra. This isobutylene trimer is not a single chemical compound, but is a collection of isomeric C12 olefins (dodecenes) and is obtained when an appropriate mixture of isomeric dodecyl mercaptans is heated in a vulcanization mix. Such a mixture of mercaptans is a commonly used ingredient of an emulsion polymerization, such as for SBR or NBR, and the interconversion between... 

One benefit of the emerging understanding of vulcanization fume is an appreciation of the potential for controlling the release of a vapour from rubber. This is control at source in the stricter sense as previously applied (Section 3.4) to the control of dust generation from solid additives. Examples of the implementation of this approach to control specific component emissions include the removal of Nonox or NDPA from rubber formulations and their replacement by safer alternatives. Such control at source has been described in general terms as achievable in two ways. ... 

When pure, sulfur monochloride is a light yellow oily liquid with an unpleasant pungent odor, which fumes in moist air and hydrolyzes in water to give sulfur dioxide, hydrogen sulfide, and hydrochloric add. The chloride is soluble in a variety of inert organic solvents and it finds wide commercial use in the rubber industry in the vulcanization process. 

The bare vulcanized silicone pol)mier, a polydimethylsiloxane network, shows only a low mechanical strength. Adding 30 wt. % of fumed silica by mixing and dispersing increases the elongation and stress at break by a factor larger than 10 (Fig. 8). 

For example, in heat-cured mbber systems a common loading with synthetic silica is around 30%. For economic reasons, precipitated silicas are used in increasing volumes in silicone elastomers such as high-consistency mbber (HCR), liquid silicone mbber (LSR), and two-component room temperature vulcanized elastomers (RTV2). The reinforcement provided by precipitated silicas is only slightly lower than that provided by fumed silicas. However, fumed silicas are necessary in silicone sealants and other high-end applications because of their desirable properties like low moisture content. 

Synonyms Polydimethylsiloxane elastomer Polydimethylsiloxane rubber Polysilicone Silicone mbber IMinition Room-temp, vulcanizing silicone mbber Properties Sol. in org. soivs. dens. 1.12 (20C) low surf, tension Toxicology TDFo (implant, rat) 1500 mg/kg skin and eye irritant questionable carcinogen experimental lumorigen Hazardous Decanp. Prods. Heated to decomp., emits acrid smoke and imtating fumes... 

Hazardous Decomp. Prods. CO, CO2, heated to decomp., emits toxic fumes of NOx NFPA Health 4, Flammability 3, Reactivity 1 Uses Rubber vulcanizer organic synthesis raw material for herbicides, ion exchange resins, pharmaceuticals, water-sol. polymers... 

Precaution Exposed to flame, emits acrid fumes dust is sensitive to ignition Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of SOx and NOx Uses Accelerator for nat. and syn. rubbers (nitrile, SBR) plasticizer vulcanization... 

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of Cr Uses Catalyst, crosslinking agent used for curing heat-vulcanized silicone rubbers, food-contact rubber articles Manuf./Distrib. Gelest http //www.geiest.com Trade Name Synonyms Aztec DCLBP-50-PSI [Aztec Peroxides] Perkadox PD t[Flexsys http //www. fiexsys. com]... 

Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of NOx and SOx Uses Primary vulcanization accelerator, thiazole secondary accelerator for rubber molded and extruded goods accelerator for food-contact rubber articles for repeated use Regulatory FDA 21CFR 177.2600 Manuf./Distrib. Akzo Nobel http //www. akzonobei. com Trade Name Synonyms Akrochem Accelerator Cu.D.D. [Akrochem http //www.akrochem.com], Akrochem Accelerator Cu.D.D.-PM [Akrochem http //www.akrochem.com]-, Cumate t[R-T. Vanderbilt http //www.rtvanderbiit.com]. Methyl Cumate [R.T. Vanderbilt http //www.rtvanderbiitcom], Methyl Cumate Rodform t[R.T. Vanderbilt http //www. rtvanderbiit. com]... 

Toxicology LD50 (IV, mouse) 178 mg/kg TDLo (oral, rat, 78 wks continuous) 1365 g/kg highly toxic poison by IV route mod. toxic by ing. primary irritant suspected carcinogen tumorigen mutagen TSCA listed Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Uses Accelerator in vulcanizing rubber... 

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