Small-angle neutron scattering blends

Briber RM, Bauer BJ (1991) Macromolecules 24 1899. By small-angle neutron scattering from blends of cross-linked and liner polystyrene they found that the intensity increased as the cross-link density was increased. This finding apparently contradicts our theoretical expression (4.11) below. See Sect. 4-4 for a comment on this point... 

Whitmore and Noolandi (1985b) developed the self-consistent field theory to examine micellization in AB diblocks in a blend of AB diblock and A homopolymer solvent . The model was applied specifically to the case of PS-PB diblocks in PB homopolymer for comparison with the results of small-angle neutron scattering (SANS) experiment by Selb et al. (1983). This model is discussed in more detail in Section 3.4.2. 

Since its introduction in the early 1970s, the small angle neutron scattering (SANS) method has had a substantial impact on polymer research. When used with partially deuterated polymers, SANS permits a close monitoring of macro-molecular conformations in polymer solutions, melts, and blend mixtures. This advantage has made it a unique tool for the understanding of the morphology of polymer materials and of the relationship between their structures and physical properties. 

The presence of SEBS at the interface was confirmed by small angle neutron scattering (SANS) experiments run on blends where the dispersed component, either sPS or HDPE, had been alternatively deuterated [34]. 

The Flory interaction parameter in miscible polymer blends is measured using small-angle neutron scattering, usually involving deuterium label-... 

We can exploit mixtures of per-deuterated and per-hydrogenated polymers in small-angle neutron scattering measurements to reveal information on the configuration of individual chains as well as assemblies of chains in the case of phase separating blends, block copolymers, and other inhomo-... 

Many LLDPE are compositionally heterogeneous, since they contain molecules with few branches and molecules that are highly branched. The more highly branched fraction can be separated by solvent extraction. Small-angle neutron scattering (SANS) has confirmed the prediction that stmcturally disperse LLDPE display liquid-liquid phase separation, even if the overall branch content is low. These LLDPE behave like polyethylene blends even though they are the result of a single polymerization. 

For homopolymer blends consisting of deuterated (labeled) polymer molecules randomly dispersed or dissolved in a protonated polymer matrix, small-angle neutron scattering in the Guinier region arises from the contrast between the labeled (deuterated) and the protonated species. The scattering cross-section can be expressed... 

Mehta, R., and Dadmun, M. D. 2006. Small angle neutron scattering studies on miscible blends of poly(styrene-rfln-vinyl phenol) with liquid ciystalline polyurethane. Macromolecules 39 8799-8807. 

Yurekli, K., and R. Krishnamoorti. 2004. Thermodynamic interactions in blends of poly(4-tert-butyl styrene) and polyisoprene by small-angle neutron scattering. /. Polym. Set. Part B Polym. Phys. 42 3204-3217. 

The presence of CO2 in UCST polymer blends has been shown to enhance blend miscibility. Walker et al. [136] observed a depression of the cloud point temperature for low-molecular-weight blends of polystyrene/polyisoprene using a combination of visual inspection, small-angle neutron scattering, and spectrophotometry. In the presence of 13.8 MPa of CO2, a reduction of the cloud point was observed compared to the same system in the absence of SCCO2. This demonstrates the ability of CO2 to promote miscibihty in UCST blends, and consequently an increase in the processing window is available. Walker et al. [137]... 

Most of the data presented in this chapter were obtained by applying RPA to small angle neutron scattering profiles from homogeneous homopolymer blends. This approach was pioneered by Herkt-Maetzky and Schelten, Murray et al., and Hadziioannou and Stein [20-22]. The composition and molecular weight dependence of x thus obtained has been studied in some systems. While x is generally... 

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