Blends amorphous polymer

Perrin P, Prudhomme RE. SAXS measurements of interfacial thickness in amorphous polymer blends containing a diblock copolymer. Macromolecules 1994 27 1852-1860. 

Table 3.16. Influence of and upon the nucleation behavior in crystalline/amorphous polymer blends...

Table 3.17. Influence of compatibiUzers on the nucleation behavior of the semicrystalline matrix in crystaUine/amorphous polymer blends... 

Table 3.19. Expressions for the dissipation energy terms and corresponding spherulite growth rates in a crystalline/amorphous polymer blend system [Martuscelli, 1984 Baitczak et al., 1984]...

Table 3.23. Overview of literature in which the final semicrystalline morphology in immiscible crystaUine/amorphous polymer blends has been studied...

In most immiscible crystalhne/amorphous polymer blends, the crystallization of the dispersed phase occurs in the presence of a molten matrix phase. In the following description, examples will be categorized according to the major classes, as listed in Table 3.14. 

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. 

Another miscible semicrystalline polymer/amorphous polymer blend SMP is a polyethylene oxide (PEO)/novolac-type phenolic resin blend [24]. The blend was found to be completely miscible in the amorphous phase when the phenolic content is up to 30 wt%, and the crystalline melting temperature (T,f) of the PEO phase working as a transition temperature can be tuned. 

Kelusky et al. also indicated that by use of a semi preparative TREF system one could achieve an effective characterization of PE/EPDM terpolymer and PE/polyisobutylene blends. The approach for this type of analysis of blends, in which one of the components was non-crystalline, was to first collect the PIB or EPDM by elution at 30 °C followed by elution of the PE component as an analytical TREF or it could be eluted off, precipitated and recovered for subsequent analysis by SEC or NMR. They point out that the TREF separation of this type of mixture is superior to the usual solvent extraction methods which invariably remove some highly branched or low molecular weight PE in addition to the PIB or EPDM. One would anticipate that such a separation scheme would be effective for other crystalline/amorphous polymer blends such as impact polypropylenes which contain ethylene-propylene rubber. 

PBSA and PVPh are miscible crystalline/amorphous polymer blends. Miscibility of PBSA/PVPh blends was evidenced by the single composition-dependent glass-transition temperature over the entire blend compositions. The negative polymer-polymer interaction parameter, obtained from the melting depression of PBSA, indicates that PBSA/PVPh blends are thermodynamically miscible. 

Miscible CTystaUine/amorphous polymer blends such as PLA/PVC blends have been widely investigated, and oriented crystallization has also been applied to some miscible ciystalline/amorphous polymer blends. For miscible blends containing semicrystaUine polymers, analysis of the melting point depression is widely used to estimate the Flory-Huggins interaction parameter (x). 

In an amorphous polymer blend system, we can determine the phase boundary curve, i.e. a temperature versus composition phase diagram, by using DSC to follow the appearance of two separate T s at a certain annealing temperature. The phase diagram can also be obtained simply by optical observation. The temperature at which the first faint opalescence appears on heating is designated the cloud point. 

There are only a few compatible polymer blends without a pronounced morphology, such as PS/PPO or SAN/PMMA. The morphology of the other blends of amorphous polymers is determined by their incompatibility and processing conditions. Occasionally it can be difficult to reveal the morphology of an amorphous polymer blend in detail if there are no clear interface boundaries or the components show no different staining abilities in such cases some special preparation techniques are used. 

Chen, H.L., Li, L.J., and Lin, T.L. (1998) Formation of segregation morphology in crystaDine/amorphous polymer blends Molecular weight effect Macromolecules,... 

Figure 16.5 Lauritzen-HofFman plots showing spherulitic morphologies and kinetic regime behavior of crystalline/amorphous polymer blends in which the crystalline polymer was PCL and the amorphous polymer was varied.

Dielectric Relaxation Spectroscopy of Amorphous Polymer Blends 1853... 

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