Butadiene Specifications

Analytical methods used are described by Bianchi et al. (1997). Methods 3M 3500 and 3M 3520 involve absorption onto a butadiene-specific activated charcoal, followed by desorption with carbon disulfide or with dichloromethane, respectively, and analysis by direct-injection gas chromatography with flame ionization detection. 

Fig. 2. Construction of Heilbronner modes (a) in [4]polyacene, attachment of parameters to the perimeter clockwise from a to d determines all remaining parameters (b) in pentalene, propagation outwards from one vertex of the central bond leads to a mode with a — —b and c = 0 (c) in butadiene, specification of a single parameter on any one edge of the graph determines the whole mode.

Burke, O. W., Jr., Starr, C, E., Jr., and Tuemmler, F. D., Light Hydrocarbon Analysis, Chapter 2 of Butadiene Production Processes, Committee on Butadiene Specifications and Method of Analysis, New York, Reinhold Publishing Corp., 1951. 

Due to the inherent danger of peroxides in butadiene, specification limits are usually set for their presence. This test method will provide values that can be used to determine the peroxide content of a sample of commercial butadiene. 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

Catalytic Cracking. This is a refinery process that produces a mixture of butylenes and butanes with very small amounts of butadiene. The specific composition of the mixture depends on the catalyst and process conditions. Most catalytic cracking processes employ temperatures about... 

An orbital correlation diagram can be constructed by examining the symmetry of the reactant and product orbitals with respect to this plane. The orbitals are classified by symmetry with respect to this plane in Fig. 11.9. For the reactants ethylene and butadiene, the classifications are the same as for the consideration of electrocyclic reactions on p. 610. An additional feature must be taken into account in the case of cyclohexene. The cyclohexene orbitals tr, t72. < i> and are called symmetry-adapted orbitals. We might be inclined to think of the a and a orbitals as localized between specific pairs of carbon... 

Other additives. Amorphous polypropylene, waxes and asphalt can be added to decrease the cost of BR formulations. On the other hand, PIB can be blended with NR, styrene-butadiene rubber, EVA and low molecular weight polyethylene to impart specific properties. 

Isocyanates can be added to solvent-borne CR adhesive solutions as a two-part adhesive system. This two-part adhesive system is less effective with rubber substrates containing high styrene resin and for butadiene-styrene block (thermoplastic rubber) copolymers. To improve the specific adhesion to those materials, addition of a poly-alpha-methylstyrene resin to solvent-borne CR adhesives is quite effective [76]. An alternative technique is to graft a methacrylate monomer into the polychloroprene [2]. 

Most moisture-curing liquid adhesives utilize poly(oxypropylene) (PPG) polyols, as shown above. These raw materials produce among the lowest-viscosity prepolymers but may not have sufficient modulus at higher temperatures for some applications. A certain percentage of polyester polyols may also be utilized to boost performance, but these may cause a large increase in viscosity, and so they are more often used in conjunction with polyether polyols to provide a high-performance adhesive with workable viscosities. Poly(butadiene) polyols may be utilized for specific adhesion characteristics. 

Tower bottoms-ACN, butadiene, with some butenes and acetylenes - are fed to a recovery/stripping column. The hydrocarbons are taken overhead and then rerun to meet product specifications. The stripping column bottoms, (ACN) is then remrned near the top of the extractive distillation tower. A small slipstream goes to the ACN recovery tower, where solvent is also recovered from the water wash streams. 

Butadiene is obtained mainly as a coproduct with other light olefins from steam cracking units for ethylene production. Other sources of butadiene are the catalytic dehydrogenation of butanes and butenes, and dehydration of 1,4-butanediol. Butadiene is a colorless gas with a mild aromatic odor. Its specific gravity is 0.6211 at 20°C and its boiling temperature is -4.4°C. The U.S. production of butadiene reached 4.1 billion pounds in 1997 and it was the 36th highest-volume chemical. ... 

Acetonitrile and hydrogen cyanide are hy-products that may he recovered for sale. Acetonitrile (CH3CN) is a high polarity aprotic solvent used in DNA synthesizers, high performance liquid chromatography (HPLC), and electrochemistry. It is an important solvent for extracting butadiene from C4 streams. Table 8-1 shows the specifications of acrylonitrile, HCN, and acetonitrile. ... 

The ratio of acrylonitrile/butadiene could be adjusted to obtain a polymer with specific properties. Increasing the acrylonitrile ratio increases oil resistance of the rubber, but decreases its plasticizer compatibility. 

Solution polymerizations of 1,3-butadiene were carried out in a high-pressure glass reactor (40 mL) connected with a vacuum system. In a typical procedure, 4 pmol of precatalyst (EAS/precatalyst =100 mol/mol) was dissolved in 20 mL of toluene. The polymerization started by adding 1.08 g of 1,3-butadiene and EAS to the solution in this order. The reaction mixture was stirred at a specific temperature (30 to 70 °C) for 40 min. The resulting solution was poured into acidified methanol (100 mL of a 5% v/v solution of HCl). The polymer was then isolated by filtration and washed with methanol before drying overnight at 40 °C. Polymer yield was determined by gravimetry. 

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