Dispersed phase domains, size

Els and McGill [48] reported the action of maleic anhydride on polypropylene-polyisoprene blends. A graft copolymer was found in situ through the modifier, which later enhanced the overall performance of the blend. Scott and Macosko [49] studied the reactive and nonreactive compatibilization of nylon-ethylene-propylene rubber blends. The nonreactive polyamide-ethylene propylene blends showed poor interfacial adhesion between the phases. The reactive polyamide-ethylene propylene-maleic anhydride modified blends showed excellent adhesion and much smaller dispersed phase domain size. 

SEBS-g-MA (0-20) and dispersed phase domain size vs. volume fraction 1995 Rosch and... 

PA-6 (30-25) or PA-12/PP (60-70)/PP-MA (0-20) Internal mixer at 240 °C/TEM/mechanical properties and dispersed phase domain size vs. vol. fraction of compatibilizer/also blends containing EP rubber Rosch et al. 1996 Rosch 1995 Rosch and Miilhaupt 1993, 1995a, b... 

The presence of clay particles at the interface in a blend can occur when the interfacial energies are appropriate, and this will result in improved interfacial adhesion between the two polymer phases and a decrease in the dispersed phase domain size. The final morphology in the blend is also affected by the viscosity ratio of the dispersed and continuous phases and has been known to significantly... 

Initial morphologies of extruded strands were examined as a function of extruder rpm and blend composition. Phase contrast optical microscopy shows a 35% HDPE dispersed phase domain size to be comparable (1 p. < size < 5 p) at both 300 and 500 rpm, (Fig. 5.9). The effect of compatibilizer on domain size of the dispersed phase is shown in Fig. 5.10. 

Suppression of domain coalescence in the melt flow regime is one of the most important effects of the interfacial reaction on morphology and morphology development. Simdararaj and Macosko [33] have conducted a careful study of morphology as a function of dispersed phase voliune fraction in reactive and non-reactive blends to discern the influence of the reaction. Figure 5.9 illustrates the dependence of the dispersed phase domain size on the dispersed phase concentration for typical uncompatibilized blends. At dispersed phase concentrations less than about 0.5 wt.% the system is dilute enough that coalescence is insignificant due to the very low frequency of dispersed phase domain... 

The effects of compatibilization both by reaction and addition of block copolymers are demonstrated in Fig. 5.10. Either type of compatibilization suppresses coalescence, resulting in lower dispersed phase sizes compared to the non-compatibilized blend. The reactive compatibilization is clearly more potent than addition of block copolymer and evidently suppresses coalescence completely over the concentration of dispersed phase investigated. Curiously, in this blend neither compatibilization scheme substantially reduces the dispersed phase domain size in the low concentration limit. The reason for this is not clear, although it may be due to the presence of an interphase with different rheological properties than either of the main components. Figure 5.11 shows a more... 

Surface imaging techniques such as atomic force microscopy (AFM) and electron microscopy, while able to provide information on physical structure (filler dispersion, phase domain size and distribution) down to resolutions of 10s... 

Figure 15.7a shows that the two phases are with irregular domain sizes and shapes. This indicates that the NR/EPDM blends were completely immiscible, large EPDM domains being dispersed in the NR matrix. The average domain size of the dispersed phase was 4.1 pm. The compatibility of the NR/EPDM system was improved by the addition of a compatibilizer, as can be seen in Fig. 15.7b-g the treatment resulted in noticeable surface hardening, and the physical changes in the surface were expected to influence physically both the deformation and adhesion of the two mbbers, that is, the compatibilizers improved both the morphology and compatibility of the blends because of the reduction in the interfacial tension between EPDM and NR rubbers. The size of the dispersed phase (EPDM) domain decreased with the addition of compatibilizers, and no gross phase separation was present in the blends (Fig. 15.7). For NR/BR/EPDM, the domain size was approximately 3.8-1.26 pm NR/PVC/EPDM, 2.7-0.75 pm NR/chlorosulfonated PE/EPDM, 2-0.75 pm NR/p-radiation/EPDM 4-1.5 pm and NR/MAH/EPDM. 1-0.25 pm. These results are in agreement with the observations of Anastasiadas and Koberstein (58) and Meier (59), who reported that compatibilizers reduced the phase domain size.

The determination of T of a blend is one of the calorimetric techniques used to elucidate the miscibility or partial miscibility in the amorphous phase of binary polymer blends. Glass transition temperature is the temperature at which the transition from the glassy to the rubbery state of the bulk material takes place. The establishment of miscibility using is based on the degree of dispersion of the second component in the amorphous region of the first component and that the size of the disperse phase domain is < 15 nm (Silvestre et al., 1996 Shultz and Young, 1980). It is noteworthy that blends which exhibit a are miscible whereas... 

The study of the physical form and structure of a material. The overall physical form of the physical structure of a material on a submicron and micron scale. Common units are dispersed phase domains, lamellae, spherulites, etc. The term comprises notion of the global structure (e.g., stress-induced skin core), as well as shape, size, orientation, and distribution of the dispersed phase (solid, liquid, or gaseous). 

In the case of sequential IPNs, the phase domain size of the second polymerized polymer is governed primarily by the cross-link density of the first polymerized polymer and the overall composition. The disperse phase diameter of the second polymerized polymer, D2, assuming spheres may be written (22)... 

In dispersive mixing, the dispersed phase undergoes size reduction and forms multiple smaller domains as a result of stresses acting at the interfaces [53, 54]. In this case, the viscous forces generated in the continuous phase overcome the restoring forces due to interfacial tension [55, 56]. Hence, the extent of deformation is determined by the ratio of the viscous and interfadal stresses, the relative magnitude of which can be expressed as a dimensionless number, the so-called capillary number [57, 58]. 

In the early 1980s, a quite different, reactively compatibilized blend was introduced by DuPont, which not only controlled the dispersed phase size, but also enabled the dispersed phase domains to take on a preferred shape in later processing [25-27]. The addition of a PE-g-MA compatibilizer to a 80/20 PE/PA6 blend sufficiently strengthened the interfacial layer that melt drawing of the blend in film or bottle forming processes results in overlapping lamellae of the PA. The lamellar structure provides an excellent barrier to the diffusion of molecules soluble in the polyolefin but insoluble in PA6. This concept was commercialized by DuPont in 1982 as Selar . Other Selar grades were introduced later, in which the PA6 was replaced by amorphous PA and PET. 

Reactive compatibilization has two key effects on the final morphology of polymer blends reduction of the average size of the dispersed phase domains and narrowing of the size distribution. Both of these effects have been demonstrated by a number of workers [5,45-51]. In continuous/dispersed systems, the size of dispersed phase domains may be... 

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