Commercial polymer blends

Utracki, L. A., Commercial Polymer Blends, Chapman Hall, London (1998a). 

Note that nearly all commercial polymer blends (the exception is blend of PVDF with PMMA) are immiscible. One tends to study miscibility not to develop single-phase commercial blends, but mainly to design better compatibilizers and compatibilization strategies. 

From a commercial point of view, semicrystalline polymers are of prime importance. Among the four mostly used commodity plastics (PE, PS, PVC and PP), only PS is completely amorphous. The three semicrystalhne polymers account for the largest volume of the commercial polymer blends. A majority of the polymer blends contains at least one crystalline component. Most polymer blends are immiscible. 

Patented or commercial polymer blends are in most cases multiphase, compatibilized systems. In the old, but still popular blends of polyvinyl-... 

Table 5.1 shows North American demand for common commercial polymer blends for 1992 and projected volumes for 1997 [Freedonia, 1993], For 1997 the total North American polymer blends market was projected at 545 kton (1.2 billion pounds). 

Table 5.1. North American demand for common commercial polymer blends...

A majority of commercial polymer blends is melt-blended, mostly in TSE, less frequently in SSE, and rarely in batch mixer and other... 

Information on conditions to be used for blow molding of commercial polymer blends is limited. The available data are listed in Table 10.35. 

Table 12.25 provides information on the publications pertinent to solvent and chemical resistance of polymer blends. The chemical and solvent susceptibilities of the commercial polymer blends (as reported by the manufacturers) are listed in Table 12.26. 

Table 12.26. Chemical and solvent effects of most of the commercialized polymer blends [Utracki, 1994 Toensmeier, 1994]...

The flame retardancy properties of some commercial polymer blends are given in Table 12.34. 

Electrical properties of selected commercial polymer blends are listed in Table 12.36. 

Table 12.36. Data on some commercial polymer blends [Martino, 1994]...

In this chapter, an overview of the commercially important blends is presented with a particular emphasis on the rationale for their commercial development, the compatibilization principles, their key mechanical properties and their current applications and markets. To facilitate the discussion, the commercial polymer blends have been classified into twelve major groups depending on the type of the resin family they are based on, viz. (i) polyolefin, (ii) styrenic, (iii) vinyl, (iv) acrylic, (v) elastomeric,... 

In comparing the different blends, the specific advantages of each type, as well as any potential overlap in performance with other type of blends have also been discussed. The fundamental advantage of polymer blends viz. their ability to combine cost-effectively the unique features of individual resins, is particularly illustrated in the discussion of crystalline/amorphous polymer blends, such as the polyamide and the polyester blends. Key to the success of many commercial blends, however, is in the selection of intrinsically complementing systems or in the development of effective compatibilization method. The use of reactive compatibilization techniques in commercial polymer blends has also been illustrated under the appropriate sections such as the polyamide blends. 

To be useful, most commercial polymer blends are either designed or selected to have some degree of the technological compatibility between the components to resist delamination and loss in ductility. Compatibility is defined here as the ability for the polymer components to co-exist either as molecularly miscible or as morphologically distinct phases, but interfacially stabilized, without a tendency for delamination. 

Commercial polymer blends belong to one of the following three categories ... 

While the specific advantages of each type of the blends will be discussed later in detail for the individual cases, the general motivations for making commercial polymer blends may be any of the following factors lower cost... 

Many commercial polymer blends often include an elastomer, to improve the impact strength of the blend under conditions of stress concentration (notched Izod impact strength) and to lower the ductile-brittle transition temperature of the blend. The elastomeric dispersions are judiciously employed either in the matrix phase, in the dispersed polymer phase, or in both phases, depending upon the requirement and the fracture behavior of the blend. As a general rule, the more brittle component in a given polymer blend has a greater need for rubber toughening. 

Figure 15.3. Notched Izod impact strength vs. DTUL (in °C at 0.45 MPa) of various commercial polymer blends.

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