Linear polybutadienes

M ass Process. In the mass (or bulk) (83) ABS process the polymerization is conducted in a monomer medium rather than in water. This process usually consists of a series of two or more continuous reactors. The mbber used in this process is most commonly a solution-polymerized linear polybutadiene (or copolymer containing sytrene), although some mass processes utilize emulsion-polymerized ABS with a high mbber content for the mbber component (84). If a linear mbber is used, a solution of the mbber in the monomers is prepared for feeding to the reactor system. If emulsion ABS is used as the source of mbber, a dispersion of the ABS in the monomers is usually prepared after the water has been removed from the ABS latex. 

Table II. Molecular Weight and Viscosity Data for Linear Polybutadienes...

Table 9-2 summarizes differences between polybutadiencs produced by different processes. The low c/i-content polybutadienes are branched. Tliey have lower solution viscosities than their linear counterparts and are preferred for manufacture of high impact polystyrene (HIPS) in which polymerization takes place in a solution of the elastomer in styrene. As the reaction proceeds under agitation, polystyrene becomes the continuous phase, with dispersed droplets of rubber (see Chapter 11). The high m-content, linear polybutadienes are more elastomeric... 

Mooney-Rivlin plots for uniaxial tension data on three networks prepared from radiation-crosslinking a linear polybutadiene melt with------------------... 

An example of the linear viscoelastic response in oscillatory shear for a nearly monodisperse linear polybutadiene melt is shown in Fig. 1.2%. Extrapolation of the limiting power laws oiG uP and G" u (the dashed lines in Fig. 7.28) to the point where they cross has special significance. The intersection of the power laws G = J qrj uP and G = t]uj using the above two equations allows us to solve for the frequency where they cross uj= l/(/)/eq), which is the reciprocal of the relaxation time r [Eq. (7.132)]. The modulus level where the two extrapolations cross, obtained by setting a = 1/r = 1 /(/ /eq) iti either equation, is simply the reciprocal of the steady... 

The diffusion coefficient ot the chain is controlled by the reptation time [Eq. (9.12)]. The linear polybutadiene chain with M= 130000gmol has A =1240 Kuhn monomers, with Kuhn length /)=10A and coil size R — hy/N = 350 A. Since linear polymers move a distance of order their own size in their reptation time, the reptation time of ri-ep = 0.2s at 25 °C enables estimation of the diffusion coefficient 6x... 

The solution viscosity of a linear polybutadiene made with butyl lithium in the 50 to 150 x 103 molecular weight range in 15% cyclohexane solution decreases in the sequence of buta-dienyl active end > isoprenyl active end > styrenyl active end > terminated. 

In highly idealized cases simple behavior is oberved. With glass beads or medium thermal black in linear polybutadiene of modest molecular weight and narrow molecular weight distribution most of the complications mentioned are absent. The polymer does not break down on milling and there is no possibility of preferential adsorption effects. The unfilled polymer exhibits Newtonian flow up to relatively high shear rates, while the fillers are essentially structure-less and have large, spherical particles. Because the interfacial surface area is small,... 

Linear polybutadiene oligomers of a mixed microstructure of PBN and Ricon 130 was found to be optimal as the basic polymer for RubCon. 

To improve dyeability, flexibility, and toughness of isotactic polypropylene, PP, it was compounded in a Banbury-type mixer with ethylene-vinyl acetate, 7 wt% EVAc. Several other ethylene copolymers were also used. In Miliprint patent, EVAc or ethylene-ethyl acrylate copolymer, 18-32 wt% EVAc or EEA, was found to improve impact strength, elongation, and low brittleness temperature of PP. hi Firestone patent, linear polybutadiene, BR, was used. The Mitsubishi patent disclosed improvements of PP impact strength properties by blending it with 0.5-25 wt% ethylene-aliphatic esters, e.g., EVAc... 

To improve the processibility of linear polybutadiene with its narrow molecular weight distribution, one can continuously add initiator in the course of the polymerization, vary the reaction temperature, or force long-chain branching by addition of divinyl compounds [68-74]. Addition of small amounts of ethers or tertiary amines alters the vinyl content from some 12% to more than 70% (Table 2). Bis(2-methoxy)ethyl ether and l,2-bis(dimethylamino)ethane as well as crown ethers [75,76] are particularly effective. The microstructures of the products are determinated by IR [77-87], NMR [88-99], x-ray diffraction, and other methods [100,101]. 

Struglinski Mark, and Graessley William. Effects of polydispersity on the linear viscoelastic properties of entangled polymers. 1. Experimental observations for binary mixtures of linear polybutadiene. Macromolecules. 18 no. 12 (1985) 2630-2643. 

Experimentally, is approximately 0.6. Thus, for branched polymers in the entanglement region, both rjo and may be quite large compared with the values for linear polymers of the same molecular weight. The terminal zone is inherently broader for well-entangled branched polymers than it is for linear polymers of comparable polydispersity [49]. The complex viscosities for a nearly monodisperse linear polybutadiene and three-arm polybutadiene star, shown in Fig. 3.24 for other purposes, exemplify the more gradual transition from Newtonian to power-law... 

What is the terminal relaxation time of a linear polybutadiene with cis trans vinyl = 55 38 7 and nearly uniform molecular weight 347,000, at 25°C ... 

Spirkova M (2002) Polyurethane Elastomers Made from Linear Polybutadiene Diols, J Appl Polym Sci 85 84-91. 

Figure 8.36 Scaling pre factora as a function of M using results from Refs. (O) (4) for polystyrene in CCI4, ( ) (16), ( ) (25,24), (A) (9), (A) (21,23) with linear chains, (+) (21,22) with/ = 3, (X) (21) with / = 8, (El) (23) with /=18, (1), ( ) (2), (V) (4) for polymers in C6D6, ( ) (10), (0) (27), ( ) (26), ( ) (22) for linear polybutadiene, ( ) (22) for / = 3 polybutadiene, (>) (2) for PEO in water, and (<) (3) for xanthan in water. Dashed line indicates best-fit line with a jj O.98 Solid line is the no-free-parameter prediction of a from the hydrodynamic scaling model, Chapter 17. Other details as in Figure 8.34.

E. D. von Meerwall, D. H. Tomich, J. Grigsby, et al. Self-diffusion of threearmed star and linear polybutadienes and polystyrenes in tetrachloromethane solution. 

Solution studies showing a transition include Colby, et al. (36), Malkin, et al. (38), and Raspaud, et al. (44) on linear polybutadiene solutions, Mochalova, et al. (39) on polyisobutylene solutions, Roovers(43) on many-arm polybutadiene star polymers, Graessley, et al. (54) on linear polyisoprenes, Koenderinck, et a/. (48) and Milas, et al. (49) on xanthan water, Lin and Phillies(45,46) on polyacrylic acid water, Ohshima, et al. (41,42) on poly- -hexyUsocyanate in dichloromethane and toluene, and Phillies and collaborators(15,47) on hydroxypropylcellulose water. 

Figure 13.9 (a,b) Storage and loss moduli of (bottom to top at left axis) 200, 350, 517, and 813 kDa linear polybutadiene solutions at concentration 67.6 g/1, based on experiments of Menezes and Graessley(20). 

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