Polybutadiene liquid

Polybutadiene is also produced in low volume as specialty products. These include low-molecular-weight, liquid 1,2-polybutadienes (60-80%, 1,2 content) used as potting compounds for transformers and submersible electric motors and pumps, liquid trans-1,4-polybutadienes used in protective coatings inside metal cans, and hydroxy-terminated polybutadiene liquid resins for use as a binder and in... 

Other references (28,29) show the use of telechelic polybutadiene liquids in photocurable printing or flexographic printing plates. While these are not... 

Liquid rubbers In order to improve the flexibihty of short glass fiber-reinforced epoxy composites, Kaynak et al. [53] modified the epoxy resin matrix with hydroxyl-terminated polybutadiene (HTPB) liquid mbber. A silane coupling agent was also used to improve the interfacial adhesion between glass fibers and epoxy matrix. However, Humpidge et al. [54] reported some unique processing problems for the resulting pasty mixmres when short textile fibers were incorporated in a hquid mbber medium. 

This most simple model for the relaxation time spectrum of materials near the liquid-solid transition is good for relating critical exponents (see Eq. 1-9), but it cannot be considered quantitatively correct. A detailed study of the evolution of the relaxation time spectrum from liquid to solid state is in progress [70], Preliminary results on vulcanizing polybutadienes indicate that the relaxation spectrum near the gel point is more complex than the simple spectrum presented in Eq. 3-6. In particular, the relation exponent n is not independent of the extent of reaction but decreases with increasing p. 

The hydrogenation in a liquid-liquid system with ionic liquids as the catalyst phase was also applied to the hydrogenation of polymers. The first studies were presented by the group of Rosso et al. [91], who investigated the rhodium-catalyzed hydrogenation of polybutadiene (PBD), nitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) in a [BMIM][BF4]/toluene and a [BMIM][BF4]/tolu-ene/water system. The activity of the catalyst followed the trend PBD>NBR> SBR, which is the same order as the solubility of the polymers in the ionic liquid. The values in percentage total hydrogenation after 4 h reaction time were 94% for PBD and 43% for NBR, and after a reaction time of 3 h was 19% for SBR. 

For the hydrogenation ofpolystyrene-fo-polybutadiene-fo-polystyrene (SBS) block co-polymer with Ru-TPPTS complex as catalyst, Jang et al. [92] applied a poly-ether-modified ammonium salt ionic liquid/organic biphasic system (Fig. 41.3). 

Figure 25. Evolution with time of the chemical reaction in liquid butadiene at 0.6 GPa and 300 K. Upper panel Purely pressure-induced reaction, the formation of vinylcyclohexene is revealed by the growth of the bands of the dimer in the 650- to 750-cm frequency range. Lower panel In this case the reaction is assisted by the irradiation with few milliwatts of the 488-nm line of an Ar+ laser. The fast increase of the characteristic polymer band at 980 cm indicates the selective formation of polybutadiene.

Another major use of butadiene polymer is in the manufacture of HIPS. Most HIPS has about 4%i-12%i polybutadiene in it so that HIPS is mainly a PS-intense material. Here, the polybutadiene polymer is dissolved in a liquid along with styrene monomer. The polymerization process is unusual in that both a matrix composition of PS and polybutadiene is formed as well as a graft between the growing PS onto the polybutadiene is formed. The grafting provides the needed compatibility between the matrix phase and the rubber phase. The grafting is also important in determining the structure and size of rubber particles that... 

Monomer and initiator must be soluble in the liquid and the solvent must have the desired chain-transfer characteristics, boiling point (above the temperature necessary to carry out the polymerization and low enough to allow for ready removal if the polymer is recovered by solvent evaporation). The presence of the solvent assists in heat removal and control (as it also does for suspension and emulsion polymerization systems). Polymer yield per reaction volume is lower than for bulk reactions. Also, solvent recovery and removal (from the polymer) is necessary. Many free radical and ionic polymerizations are carried out utilizing solution polymerization including water-soluble polymers prepared in aqueous solution (namely poly(acrylic acid), polyacrylamide, and poly(A-vinylpyrrolidinone). Polystyrene, poly(methyl methacrylate), poly(vinyl chloride), and polybutadiene are prepared from organic solution polymerizations. 

In solution, block copolymers display interesting colloidal and interfacial properties. They can be used as emulsifying agents in water-oil and oil-oil systems (6 ). In the later case, the oil phases are solid and they give rise to polymeric alloys (7.) or they are liquid and they allow the preparation of latexes in organic medium (8 ). However, the molecular structure of block copolymers based on polybutadiene PB (70 ) and polystyrene PS behave as thermoplastic elastomers when engaged in multiblock (PB-PS)n or triblock (PS-PB-PS) structures but never when implied in inverse triblock or diblock arrangements. Similarly the... 

Low molecular weight polybutadienes with terminal pyridine groups, like their hydrogen terminated counterparts, are mobile liquids. However, when quaternized in bulk with benzyl bromide (equation 3) they are transformed into solid materials. This... 

Anionic polymerization has also been used to make telechelic polymers (Greek telos, end, and chele, claw), i.e., polymers with reactive terminal groups.We coined the term, telechelic in 1957 and it has been accepted ever since in technical as well as patent literature. Liquid carboxy- and hydroxy telechelic polybutadienes initiated with difunctional organolithium initiators are commercially produced since 1962. Some of the physical properties,production details and uses as in solid rockets... 

Liquid Rubber Cure of Tristar Polybutadienes. Tristar -OH terminated polybutadienes were converted to three dimensional networks in a diisocyanate liquid... 

Tristar polybutadienes prepared by the intermediacy of lithium acetal initiators were also converted to three dimensional networks in a liquid rubber formulation using a diisocyanate curing agent. Table IV shows normal stress-strain properties for liquid rubber networks at various star branch Hn s. It can be seen that as the branch Mn increases to 2920, there is a general increase in the quality of the network. Interestingly, the star polymer network with a star branch Mn of 2920 (Mc=5840) exhibits mechanical properties in the range of a conventional sulfur vulcani-zate with a Me of about 6000-8000. 

Natural Rubber and Synthetic Polyisoprene Polybutadiene and Its Copolymers Polyisobutylene and Its Copolymers Ethylene-Propylene Copolymers and Terpolymers Polychloroprene Silicone Elastomers Fluorocarbon Elastomers Fluorosilicone Elastomers Electron Beam Processing of Liquid Systems Grafting and Other Polymer Modifications... 

Abbreviations coiX-V] = copolymers of X and Y colX-b-Yl = block copolymers of poly X and poly Y ST = styrene MA = methyl acrylate MMA = methyl methacrylate AN = acrylonitrile BD = butadiene LR (liquid rubbers) = a, cj-polybutadiene-diols and -dicarboxylic acids Cell-Ac = cellulose acetate Cell-N02 = cellulose nitrate. 

Some technological information on the Aerojet General Corporation s composite propellants technology was published recently [20]. Ammonium perchlorate is ground to the particle sizes ranging from 1 to 200 fx and then mixed to form a blend of the various particle sizes which gives the best mechanical and ballistic properties. Ammonium perchlorate is mixed with liquid polybutadiene-acrylonitrile fuel, liquid plasticizer and aluminium powder (Fig. 118). The motor casing is coated internally... 

The homogeneous palladium-catalyzed process for acetoxylation was never commercialized because of low selectivity and the difficulty in separating the catalyst from the reaction mixture. Heterogeneous palladium catalysts applied in the gas phase, in turn, quickly lose activity caused by buildup of polybutadiene. The Mitsubishi process uses a Pd-Te-on-active-carbon catalyst in the liquid phase. Tellurium apparently prevents palladium elution to acetic acid. 

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