1,4-Polybutadiene critical mixture

Fig. 6a. Structure factor S(q, t) plotted vs time for a nearly symmetrical critical mixture (< >c = 0.486) of perdeuterated and protonated 1,4 polybutadiene degrees of polymerization Nh = 3180, Nd = 3550, polydispersity indices (Nw/Nn)h = 1.03 and ((Nw/Nn)d = 1.07 quenched from T0 75 °C to T 49 °C (Tc = 61.5 1.5 °C) for several representative scattering wave numbers q. Since the scattering intensity is plotted on a logarithmic scale, straight lines imply an exponential growth and their slope hence yields 2t 1 - Eq. (76). Arrows show the time tm where nonlinear effects start to limit the growth, b Cahn plot R(q) /q2 vs q2, for the quenching experiment of a), cf. Eq. (85). Deviations from linearity here are attributed to the neglect of thermal noise - i.e. only the first term on the right hand side of Eq. (76) is kept. From Bates and Wiltzius p6]...

Figure 7.3 Transient morphologies of phase-separating polymer blends with and without nanoparticles, (a) Optical micrograph of a phase-separating deuterated polystyrene (dPS)/polybutadiene (PB) 70 30 critical mixture after coarsening for 1510 min at 25 °C [40] (b) snapshot of a Langevin dynamic simulation ofa critical (50 50) AB-mixture, with...

Phase Relationships. The first systematic investigation of the two-phase behavior of polymer/polymer/solvent systems was probably made by Dobry and Boyer-Kawenoki (2) for a variety of polymer pairs, and more recently this work was extended by Kern and Slocombe (3) and Paxton (35) to a number of other systems including several vinyl polymers. Typically, the three-component phase behavior is as shown in Figure 19 for the polystyrene/polybutadiene/benzene system (2), where a one-phase (polystyrene/polybutadiene/benzene) region is separated by a phase boundary from a two-phase (polystyrene-rich/benzene and polybutadiene-rich/benzene) mixture. As with any three-component system of this type, a critical point exists somewhere near the maximum of the phase boundary, and appropriate tie lines give the compositions and amounts of the respective phases in the two-phase region. 

Crawford bomb 66 cresylite = mixture of trinitrocresol and picric acid (french) crimping 66 critical diameter 66 CR-propellants = RDX containing rifle powders (USA) cross section ratio -> propellant area ratio 269 crusher 149 362 C.TD. = coefficient of detonation transmission (coefficient de self exitation) (french) 87 CTPB = carboxyl-terminated polybutadiene (USA) 61 329 cumulative priming 66 c.u.p. = coefficient d utilisation pratique (french) 198 cuprene 52 cupric salicylate 163 curing 67... 

The critical block sizes needed for domain formation are greater than those needed for phase separation in physical mixtures of the corresponding homopolymers. This is because the conformational entropy of parts of molecules in the block domains is not as high as in mixtures, since placement of segments is restricted by the unlike components to which they are linked. Thus the minimum molecular weights of polystyrene and c/i-polybutadiene for domain formation in AB block copolymers of these species are about 5,000 and 40,000, respectively [29]. 

Fig. 9. A comparison of the late stage scaling function of near critical polybutadiene/polyisoprene (PB/PI) mixtures at T = 55 °C with that of deuterated poly-butadiene/polybutadiene mixture [36], DPB/PB and of an iso-butyric acid/water mixture [181] I/W. Note the asymptotic exponents F(x < 1) ocx and F(x > 1) ocx-4. From Takenaka and Hash-imoto [180]...

FIGURE 23.13. (Q) VS Q for blend of 69 vol% protonated and 31% deuterated 1, 4-Polybutadiene at the critical composition. The cunres were obtained from the homogeneous mixture scattering function by adjusting xhd (one adjustable parameter). Reprinted with permission from F. S. Bates, G. D. Wignall and W. C. Koehler, Phys Rev. Lett., 55, 2425 (1985). Copyright (1985) American Physical Society. 

Fig. 7.19. dS /d ( 2) versus Q for a blend of 69 vol% protonated and 31 % deuter-ated 1,4-polybutadiene at the critical composition. The curves were obtained from the homogeneous-mixture (RPA) scattering function by adjusting Ahd- (Reproduced with permission from [66]. Copyright 1993 American Chemical Society.)... 

A binary mixture of deuterated polybutadiene (DPB) and polybutadiene (PB) was used to investigate the phase-separation processes of SD. Detailed information about the DPB/PB mixture, e.g., molecular characteristics, phase diagram, and sample preparation, can be found elsewhere [72]. Note that the DPB/PB mixture used here has an upper critical solution temperature (UCST)-type phase diagram and it requires homogenization by mechanical mixing [73] in order to bring the system to the single-phase state. The thickness of the mixture, D, was 200 fim. 

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