Ethylene-butadiene copolymerization

Boron Bromide. Approximately 30% of BBr produced in the United States is consumed in the manufacture of proprietory pharmaceuticals (qv) (7). BBr is used in the manufacture of isotopicaHy enriched crystalline boron, as a Etiedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in semiconductor doping and etching. Examples of use of BBr as a catalyst include copolymerization of butadiene with olefins (112) polymerization of ethylene and propylene (113), and A/-vinylcarbazole (114) in hydroboration reactions and in tritium labeling of steroids and aryl rings (5). 

About half of the styrene produced is polymerized to polystyrene, an easily molded, low-cost thermoplastic that is somewhat brittle. Foamed polystyrene can be made by polymerizing it in the presence of low-boiling hydrocarbons, which cause bubbles of gas in the solid polymer after which it migrates out and evaporates. Modification and property enhancement of polystyrene-based plastics can be readily accomplished by copolymerization with other substituted ethylenes (vinyl monomers) for example, copolymerization with butadiene produces a widely used synthetic rubber. 

Emulsion polymerization was first employed during World War II for producing synthetic rubbers from 1,3-butadiene and styrene. This was the start of the synthetic rubber industry in the United States. It was a dramatic development because the Japanese naval forces threatened access to the southeast Asian natural-rubber (NR) sources, which were necessary for the war effort. Synthetic mbber has advanced significantly from the first days of balloon tires, which had a useful life of 5000 mi to present-day tires, which are good for 40,000 mi or more. Emulsion polymerization is presently the predominant process for the commercial polymerizations of vinyl acetate, chloroprene, various acrylate copolymerizations, and copolymerizations of butadiene with styrene and acrylonitrile. It is also used for methacrylates, vinyl chloride, acrylamide, and some fluorinated ethylenes. 

In these equations I is the initiator and I- is the radical intermediate, M is a vinyl monomer, I—M- is an initial monomer radical, I—MnM- is a propagating polymer radical, and and M7 are polymer end groups that result from termination by disproportionation. Common vinyl monomers that can be homo-or copolymerized by radical initiation include ethylene, butadiene, styrene, vinyl chloride, vinyl acetate, acrylic and methacrylic acid esters, acrylonitrile, IV-vinylimidazole, IV-vinyl-2-pyrrolidinone, and others (2). 

As shown in Fig. 8, similar tendencies were detected considering the allyl alcohol copolymerization with ethylene, butadiene or styrene. Here, different curve progressions are observed depending on the types of comonomers, their ratio in the precursor mixture, and the plasma parameters. These deviations were attributed to the different tendencies to undergo a copolymerization, for example expressed in copolymerization parameters, which are also valid for the plasma-initiated gasphase copolymerization. 

Ethylene has been reported to copolymerize with butadiene using bisfylide)-stabilized nickel catalysts. Ostoja Starzewski, K. A. DE 3916211 to Bayer A. G., Fed. Rep. Ger., priority date May 18, 1989. Similar catalysts also provide styrene terminated oligomers of ethylene. Ostoja Starzewski, K. A. DE 4018068 to Bayer A. G., Fed. Rep. Ger., priority date June 6, 1990. 

As shown in Fig. 18.4, similar tendencies were found for the aUyl alcohol copolymerization with ethylene, butadiene, or styrene. Here, the curves are observed to progress from a parabolic (ethylene) to a nearly linear correlation (butadiene) and to an anti-parabolic behavior (styrene) between measured OH group concentrations and the stoichiometry of the precursor mixture. 

Examples of the thermoplastic elastomers include polystyrene-fi/ocA -polybutadiene-h/oc -polystyrene (SBS) or the saturated center block counterpart (SEES). In the latter, the EB stands for ethylene-butylene, where a combination of 1,2 and 1,4 copolymerization of butadiene on hydrogenation presents the appearance of a random copolymer of ethylene and butylene (see Table 9.4). 

The stirred flow reactor is frequently chosen when temperature control is a critical aspect, as in the nitration of aromatic hydrocarbons or glycerine (Biazzi process). The stirred flow reactor is also chosen when the conversion must take place at a constant composition, as in the copolymerization of butadiene and styrene, or when a reaction between two phases has to be carried out, or when a catalyst must be kept in suspension as in the polymerization of ethylene with Ziegler catalysts, the hydrogenation of a-methylstyrene to cumene, and the air oxidation of cumene to acetone and phenol (Hercules Distillers process). 

The ethylene-propylene (EP), ethylene-butadiene (EB) and propylene-butadiene (PB) copolymerizations and ethylene-propylene-butadiene (EPB) terpolymerization with a supported catalyst, TiCl4/MgCl2/ethyl benzoate-AlEt3, are described. The catalytic activities were enhanced in the EP copolymerizations, while the catalytic activities were decreased in the co- and terpolymerizations containing butadiene as compared with the corresponding homopolymerizations. It was found that the butadiene units in these co- and terpolymers are mostly in trans-1,4 configuration and long blocked sequences. 

The copolymerizations between monoolefins and dienes have been considered to be of practical and theoretical importance. As reported in the literatures ethylene-butadiene and propylene-butadiene copolymers can be prepared with conventional Ziegler-Natta titanium-based or vanadium-based catalysts. The copolymer composition and monomer sequence distribution strongly depend on the catalyst system and polymerization conditions. Alternating copolymers were synthesized when the catalyst components were mixed at the... 

Through a cracking process, propane is converted to ethylene, a key intermediate in the manufacture of a number of elastomers. In the production of SBR, ethylene is reacted with benzene to generate ethylbenzene, which is then dehydrogenated to styrene monomer, which is copolymerized with butadiene to give SBR. 

Apart from poly(ethylene glycol), other hydroxyl-terminated polymers and low-molecular weight compounds were condensed with ACPC. An interesting example is the reaction of ACPC with preformed poly(bu-tadiene) possessing terminal OH groups [26]. The reaction was carried out in chloroform solution and (CH3CH2)3N was used as a catalyst. MAIs based on butadiene thus obtained were used for the thermally induced block copolymerization with styrene [26] and dimethyl itaconate [27]. 

We have considerable latitude when it comes to choosing the chemical composition of rubber toughened polystyrene. Suitable unsaturated rubbers include styrene-butadiene copolymers, cis 1,4 polybutadiene, and ethylene-propylene-diene copolymers. Acrylonitrile-butadiene-styrene is a more complex type of block copolymer. It is made by swelling polybutadiene with styrene and acrylonitrile, then initiating copolymerization. This typically takes place in an emulsion polymerization process. 

Terpolymerization, the simultaneous polymerization of three monomers, has become increasingly important from the commercial viewpoint. The improvements that are obtained by copolymerizing styrene with acrylonitrile or butadiene have been mentioned previously. The radical terpolymerization of styrene with acrylonitrile and butadiene increases even further the degree of variation in properties that can be built into the final product. Many other commercial uses of terpolymerization exist. In most of these the terpolymer has two of the monomers present in major amounts to obtain the gross properties desired, with the third monomer in a minor amount for modification of a special property. Thus the ethylene-propylene elastomers are terpolymerized with minor amounts of a diene in order to allow the product to be subsquently crosslinked. 

Another important use of BC13 is as a Friedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cydophosphazenes to polymers (81,82) polymerization of olefins such as ethylene (75,83—88) graft polymerization of vinyl chloride and isobutylene (89) stereospecific polymerization of propylene (90) copolymerization of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerization of norbomene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Internal plasticizing demands a chemical relationship between the components which constitute the product. Therefore, good effects can be expected from copolymers of styrene and isobutylene, ethylene, or diolefins like butadiene or isoprene. Internal plasticizing of PVC can be effected by copolymerizing vinyl chloride with acrylates of higher alcohols or maleates and fumarates. The important ABS products are internal copolymers of butadiene, styrene, and acrylonitrile. The hardness of the unipolymers of styrene and acrylonitrile can be modified by butadiene which, as a unipolymer, gives soft, rubberlike products. As the copolymerization parameters of most monomers are known, it is relatively easy to choose the most suitable partner for the copolymerization. When the product of the r—values is l, there is an ideal copolymerization, because the relative reactivity of both monomers toward the radicals is the same. Styrene/butadiene, styrene/vinyl thiophene, and... 

The first free radical initiated copolymerization was described by Brubakerl) in a patent. A variety of peroxides and hydroperoxides, as well as, 02, were used as initiators. Olefins that were copolymerized with CO included ethylene, propylene, butadiene, CH2=CHX (X—Cl, OAc, CN) and tetrafluoroethylene. A similar procedure was also used to form terpolymers which incorporated CO, C2H4 and a second olefin such as propylene, isobutylene, butadiene, vinyl acetate, tetrafluoroethylene and diethyl maleate. In a subsequent paper, Brubaker 2), Coffman and Hoehn described in detail their procedure for the free radical initiated copolymerization of CO and C2H4. Di(tert-butyl)peroxide was the typical initiator. Combined gas pressures of up to 103 MPa (= 15,000 psi) and reaction temperatures of 120—165 °C were employed. Copolymers of molecular weight up to 8000 were obtained. The percentage of CO present in the C2H4—CO copolymer was dependent on several factors which included reaction temperature, pressure and composition of reaction mixture. Close to 50 mol % incorporation of CO in the copolymer may be achieved by using a monomer mixture that is >70 mol% CO. Other related procedures for the free radical... 

---