Polymers polybutadiene

Styrene-butadiene rubber (SBR) is the most widely used synthetic rubber. It can be produced by the copolymerization of butadiene (= 75%) and styrene (=25%) using free radical initiators. A random copolymer is obtained. The micro structure of the polymer is 60-68% trans, 14-19% cis, and 17-21% 1,2-. Wet methods are normally used to characterize polybutadiene polymers and copolymers. Solid state NMR provides a more convenient way to determine the polymer micro structure. ... 

Another class of hydrocarbon binders used in propints are the carboxy-terminated polybutadiene polymers which are cross-linked with either tris[l-(2-methyl)aziridinyl] phosphine oxide (MAPO) or combinations with phenyl bis [l -(2-methyl)aziridinyl] phosphine oxide (Phenyl MAPO). Phenyl MAPO is a difunctional counterpart of MAPO which makes possible chain extension of polymers with two carboxylic acid groups. A typical propint formulation with ballistic properties is in Table 11 (Ref 83) Another class of composites includes those using hydroxy-terminated polybutadienes cross-linked with toluene diisocyanate as binders. The following simplified equations illustrate typical reactions involved in binder formation... 

Benzoyl peroxide containing 50% water (see safety section) Polybutadiene (polymer grade)... 

Butadiene can form three repeat units as described in structure 5.47 1,2 cw-1,4 and trans-, A. Commercial polybutadiene is mainly composed of, A-cis isomer and known as butadiene rubber (BR). In general, butadiene is polymerized using stereoregulating catalysts. The composition of the resulting polybutadiene is quite dependent on the nature of the catalyst such that almost total trans-, A, cis-, A, or 1,2 units can be formed as well as almost any combination of these units. The most important single application of polybutadiene polymers is its use in automotive tires where over 10 t are used yearly in the U.S. manufacture of automobile tires. BR is usually blended with NR or SBR to improve tire tread performance, particularly wear resistance. 

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... 

Corradini, P. On the chain conformation of the high temperature polymorph of trans-1,4-polybutadiene. Polymer Letters 7, 211 (1969) see also J. Polymer Sci., Symposia 50, 327 (1975)... 

Pd(0) Tt-complexes, characteristics, 8, 316 polybutadiene polymer synthesis, 11, 720 polymerization... 

The 13C-NMR spectrum of polybutadiene polymer made by this initiator shows characteristic resonance peaks at 110-114 ppm assigned to... 

As may be seen from Fig. 3, there are no resonance peaks at 120-128 ppm characteristic of 1,4-microstructure in polybutadiene polymer. However, on addition of methanol to the chain live ends, resonance peaks at 120-128 ppm appear in ratios of 60% trans-1,4, 14% m-1,4, and 26% 1,2. This suggests that the protonation of the chain live ends with methanol is an independent reaction and does not relate to the actual structure of the propagating species. It may be said that the structure of the allylic lithium of polybutadiene (DP > 1) is postulated to exist in the 1,2-form (13). Yet hydrolysis of 13 gives mixed 1,4- and 1,2-microstructures. 

Koshechko, V.G., Titov, V.E. and Sednev, D.V. (1994) New route for producing acrylic add copolymers, based on electrochemical carboxylation of poly(vinyl halide)s and polybutadiene. Polymer 35, 1787-1788. 

The ability of Th-FFF to separate polymers by chemical composition [2] was demonstrated in the separation of polystyrene, polyisoprene and polybutadiene polymers of similar molecular weight [349] and extended to polytetrahydrofuran [350]. An impressive example of the ability to separate according to chemical composition was reported for two polymers indistinguishable by SEC (See Fig. 10). 

In this way one mole of water reacts with two moles of isocyanate. For a urethane prepolymer with an equivalent weight of about 300, it only takes 9 grams of water to effectively consume the prepolymer. This can lead not only to degraded physical properties, but it also forms gas bubbles in the proplnt which lead to voids and higher than predicted burning rates. This sensitivity to water content also exists with hydroxy-terminated polybutadiene polymers cured with... 

Some binder systems have used MAPO as the only curing system for carboxy-terminated polybutadiene polymers. Again a problem in long term stability of physical properties is sometimes encountered since MAPO is hydrolytically unstable. The following reaction is possible ... 

Barcia, F.L. Amaral, T.P. Soares, B.G. Synthesis and properties of epoxy resin modified by epoxy-terminated liquid polybutadiene. Polymer 2003, 44, 5811. 

Davis, J.A. Hergenrother, W.L. McGillivary, D.R. Valaitis, J.K. Substituted Polybutadiene Polymer and Roofing Membrane Formed Therefrom. U.S. Patent 5,126,384, Jun 30, 1992 Bridgestone/Firestone. 

Trimethylazetidine was polymerized by this macroinitiator, and ABA block copolymers were obtained. Reaction with a polyfunctional nucleophile such as diethylenetriamine leads to high molecular weight polymers and eventually cross-linking. The coupling reaction with amino-terminated polybutadiene polymers led to polyblock copolymers (47). 

Ricon. [Ricon Resins] Polybutadiene polymers thermoset for potting, molding oonqi. and castings, rubber modi-fim, wire coating, laminates, coatings. 

Grebowicz J, Aycock W, Wunderlich B (1986) Heat capacities of 1,4-polybutadienes. Polymer, 27 575... 

Moller M (1987) Structure and dynamics of the high temperature polymorphs of trans-1,4-polybutadiene. Polymer Preprints, Am. Chem. Soc. 28 (2) 395... 

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