Polybutadiene BR

Polymerization Reactions. The polymerization of butadiene with itself and with other monomers represents its largest commercial use. The commercially most important polymers are styrene—butadiene mbber (SBR), polybutadiene (BR), styrene—butadiene latex (SBL), acrylonittile—butadiene—styrene polymer (ABS), and nittile mbber (NR). The reaction mechanisms are free-radical, anionic, cationic, or coordinate, depending on the nature of the initiators or catalysts (194—196). 

FIGURE 1.12 Master curve of tear energy Gc versus rate R of tear propagation at Tg for three cross-linked elastomers polybutadiene (BR, Tg — —96°C) ethylene-propylene copolymer (EPR, Tg — —60°C) a high-styrene-styrene-butadiene rubber copolymer (HS-SBR, Tg — —30°C). (From Gent, A.N. and Lai, S.-M., J. Polymer Sci., Part B Polymer Phys., 32, 1543, 1994. With permission.)... 

Composition and microstructure determination of polybutadiene (BR) and natural rubber (NR) can be done by infrared spectra. Three different base units are possible for linear addition polymers of 1,3 butadiene units with cis or trans internal double bands from 1,4 addition and units with side vinyl groups from 1,2 addition (see Scheme 3.1a). 

Solid-state 13C NMR spectroscopy was used to study accelerated [33] and unaccelerated [34] sulfur-vulcanisation and sulfur-donor (TMTD) [35] vulcanisation of czs-polybutadiene (BR). Olefinic and methylene carbons of the czs-BR repeating unit typically resonate at 129.5 and 27.5 ppm, respectively. The dominant products occurring in the vulcanisation... 

Another good example of using Raman spectroscopy in the polymer industry is to investigate polymer blends. Raman microimages have been used to investigate the spatial distributions of the components in a blend of brominated poly(isobutylene-co-para-methylstyrene (BIMS) and cis-1-4-polybutadiene (BR) containing silica, zinc stearate, thiate, and other additives (21). A Raman spectrum of a blend is shown in Fig. 7-33. Specific bands can be assigned to BIMS, BR, silica, and zinc stearate. A 10 x 10 xm contour... 

Three diblock copolymers of cis-1,4 polyisoprene (IR) and 1,4-polybutadiene (BR) have been studied in dynamic mechanical experiments, transmission electron microscopy, and thermomechanical analysis. The block copolymers had molar ratios of 1/2, 1/1, and 2/1 for the isoprene and butadiene blocks. Homopolymers of polybutadiene and polyisoprene with various diene microstructures also were examined using similar experimental methods. Results indicate that in all three copolymers, the polybutadiene and polyisoprene blocks are essentially compatible whereas blends of homopolymers of similar molecular weights and microstructures were incompatible. 

The preferred compositions comprize 10 to 25 wt% rubber. Though many different thermoplastics can be used [Schrijver et al., 1988], the authors preferred polymers or copolymers of styrene all the data given are for Styron 686 E (RTM). A wide variety of mbbers can be used, such as polybutadiene (BR), and butadiene-acrylonitrile copolymer [Schrijver et al, 1988]. The rubbers used by the authors are listed in Table 11.55, along with their data on the irradiated and non-irradiated blends. Schrijver et al. 

Polybutadiene (BR) Yellow, blue base, smoky Disagreeable, sweet Chars readily vapor reaction neutral... 

Styrene-Butadiene Random Copolymer, 25% (wt) Styrene (SBR) Styrene-Butadiene Block Copolymer, about 25% Styrene (YSBR) Cis-1,4- Polyisoprene (Natural Rubber NR, Also Made Synthetically IR) Cis-1,4 Polybutadiene (BR) Polychloroprene (CR), Neoprene Butadiene-Acrylonitrile Random Copolymer, Variable % Acrylonitrile (NBR) Reclaimed Rubber (Whole Tires) (Mainly NR and SBR)... 

The objects of our investigations were four kinds of elastomers, of different structure and polarity, viz. cis-1,4-polybutadiene (BR)> butadiene-acrylonitrile copolymer (NBR), isobutylene-isoprene copolymers (IIR) and ethylene-propylene-diene terpolymer (EPT). They were mixed with plastomers low density polyethylene (PE] ), polystyrene (PS), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polycaproamide (PCA) and polyacrylonitrile (PAN) (Table 1). The concentration of the plastomers in the mixtures was changed in the range from 0 to 50 pph of the elastomer. The polymers were blended at temperature T = 423 K by means of the micromill of the Plasti--Corder apparatus. After 24 hours, crosslinking substances, dicurayl peroxide (DCP) or sulphur and diphenylguanidine (S, DPG), were added at room temperature. The composition of the mixtures is given in Table 2. 

Tread The wear resistance component of the tire in contact with the road. It must also provide traction, wet skid, and good cornering characteristics with minimum noise generation and low heat buildup. Tread components can consist of blends of natural rubber, polybutadiene (BR), and styrene-butadiene rubber (SBR), compounded with carbon black, silica, oils, and vulcanizing chemicals. 

Butadiene rubber polybutadiene (BR). An important type of synthetic rubber produced by cw-1,4-polymerization of butadiene. Main application in tyres. Trade names Ameripol CB (USA), Buna CB (FRG), Cariflex BR (UK), Europrene cis (I), Polysar (USA). 

The rate of chain scission is increased in the presence of active hydrogen (e.g., water), probably due to reaction with carbonyl oxides to form reactive hydroperoxides. Crosslinking products may also be formed, especially with rubbers containing disubstituted double bonds (e.g., polybutadiene, BR, and styrene-butadiene rubber, SBR). 

Pyrolysis in an inert atmosphere under precisely controlled conditions (Figure 4) generates duplicable amounts of products, which are separated by capillary GC and provide an estimate of the ratio of polymeric constituents. Natural rubber produces iso-prene and limonene as two of the characteristic products, which distinguish it from polybutadiene (BR), styrene-butadiene co-polymer (SBR), butyl rubber (HR), and some of the other polymers. Quantification involving a mixture of polymers requires calibration curves derived from similar combinations of polymers (Figure 5). Cured and uncured formulations require separate calibrations and the differences in the microstructure of a polymer affect the products obtained on pyrolysis. 

The curing and dynamic properties of precipitated nano-silica on NR without and with the sulfur addition (NR with S), synthetic polyisoprene (IR), polybutadiene (BR) and SBR was investigated. Silica was treated with bis(3-triethoxysilylpropyl)tetrasulfane (TESPT) to form bonds at interfaces. Cure, Mooney viscosity, glass transition temperature, bound rubber, crosslink density and DMA were measured. The properties of silica-filled SBR and BR correlated with highest rolling resistance and SBR-silica correlated with best skid resistance. A Payne effect was observed in the loss modulus under some experimental conditions. In addition to possible filler de-agglomeration and network disruption, the nanoscale of the filler may have further contributed to the non-linear response typified by the Payne effect. ... 

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