Salami structure

Seeded polymerization is defined as polymerization of post-added monomer in the presence of particles. A conventional example of seeded polymerization is the polymerization of styrene (St) and acryronitrile (AN) in the dispersion of polybutadiene (PB) particles. In this polymerization, a portion of St and AN penetrates into the PB particle and the other portion stays in the aqueous phase. The former graft-polymerize with PB or polymerize by themselves in PB particle. The progress of polymerization in the particle leads to phase inversion to form a salami structured particle in which PB islands are dispersed in a poly(St-co-AN) sea. St and AN in aqueous phase may polymerize to form independent particles. 

For BD15, with an alloying content of 45 wt%, as shown in Fig. 19.30c, the cavitation at the poles of PA6 particles seems to result more from the cavitation of the POE interphase than from a simple interfacial debonding (although it is not always simple to make the difference). Also, the cavitation in dispersed POE droplets is very active. Furthermore, in some micrographs a new type of salami structure is present large POE nodule containing small PA6 inclusions. Under uniaxial tension, the POE of these salami stmctures deforms easily, while the PA6 particles inside seem unaffected. 

At last for BD16 (Fig. 19.30d), in which PP is in minority, cavitation occurs more likely in POE interphase at the poles of large PA6 particles and in large isolated POE particles (that are more numerous in this blend). However, conservative deformation mechanisms become predominant and are commonly identified (i) at smaller POE droplets, (ii) at salami structures, and (iii) in the PP matrix. 

Although no generalization can be performed, it is of interest to assess that modifiers with end-groups reacting with the thermosetting polymer [107] lead to a salami structure inside dispersed phase particles, whereas non-functional-ized modifiers lead to a core-shell structure, i.e. a rigid core surrounded by an... 

This morphology was appropriately nicknamed the salami structure by M. Matsuo (private communication). 

Figure 3.7. Electron micrograph of a thin section of ABS type G polyblend after coagulation (stained with osmium tetroxide). Note the distinct salami structure due to the occlusion of AS copolymer within the rubber phase. (Matsuo et al, 1969a.)...

Transmission electron micrographs of HIPS (A) osmium-stained thin section showing salami structure, with polystyrene sub-inclusions embedded in (black) rubber phase, in a matrix of polystyrene (B) unstained thicker section stretched on the microscope stage. The unloaded specimen (A) has largely recovered, and shows compressed crazes. The stressed sample (B) shows extended craze fibrils and fibrillated rubber. (Micrographs by courtesy of R. C. Cieslinski, Dow Chemical USA.)... 

The rubber cellular domain structures are sometimes called salami structures, after their appearance. The toughness obtained in such materials is related to the rubber phase volume, which is the rubber volume plus the occluded polystyrene cellular domain volume. 

Figure 11 Cross-sectional images of the specimen shown in Figure 10(a). The black parts indicate 0s04-stained butadiene domains. The electron beam is along the Z-axis. (a, b) Cross-sectional digitally sliced images at different depths of a 1-pm-thick sample. The depths of X-Kslices are indicated by dashed lines in (c). The electron beam was incident from the top and, hence, image (b) is obtained deeper inside the thick specimen. The detailed structures of the salami structure near the surface, that is, part (a), appear to be clearer than those inside the specimen, that is, part (b). Reproduced with permission from Macromolecules, 2010, 43,1675-1688. Copyright 2010 American Chemical Society.

When structured soy protein fiber was added to fermented salami at 15 or 30% levels, trained sensory panels found the flavor to be undesirable, whereas a 116-member untrained panel found the product containing 30% soy flour to be undesirable in flavor, tenderness and overall desirability (26). The flavor of beef patties containing 20% soy protein flour or concentrate was rated about equal to all beef patties by a 52-member panel, whereas patties containing 30% were scored lower by the panel (6). Berry et al. (7) found the characteristic "soy-like" flavor to be more... 

The structure of ABS is similar to that of HIPS but with a SAN matrix instead of the PSt matrix in HIPS. PB grafted with SAN acts as a compatibilizer between the rubber particles and the SAN matrix. The rubber particle morphology in ABS can be similar to that in HIPS, with salami-type particles, but ABS particles can also be of the core-shell type, with a core of solid PB and a shell of graft copolymer, especially if the ABS is produced by the emulsion process [34]. In addition to craze formation, an important fracture mechanism in ABS polymers is shear yielding, which leads to tougher materials [46]. 

Internal structure of the rubber particles is very important from the point of view of both initiation and stabilization of the matrix deformation. Generally, three types of rubber particles are used for toughening. In HIPS and solution ABS, salami particles obtained during polymerization process are preferred. These particles contain much occluded matrix so that the particles are sufficiently large for initiating crazing, while the rubber content is relatively low, which limits the... 

There are some interesting types of structure or morphology, which are named after culinary products, like shish kebab structures (from schaschlik) in PE and PP or salami particles in HIPS. They are listed in Part III in Table 4. 

PBA particles Salami particles Sheaf-like structure Shish kebab structure Skin-core structure Spheres... 

Seraji SM, Razavi Aghjeh MK, Davari M, Salami Hosseini M, Khelgati S. Effect of clay dispersion on the cell structure of LDPE/clay nanocomposite foams. Polym Compos 2011 32 1095-105. 

The film laminated structure was curved along the shape of the specimen surface forming a bank, and the films showed wavy shape. The salami particles highly elongated and form the lines in the bank. 

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