Thermoplastic-based blend immiscible blended polymer

Immiscible thermoplastic blends based on liquid crystal polymers... 

Carbon black is the most widely used conducting filler in composite industry. Carbon black filled immiscible blends based on polar/polar (65), polar/nonpolar (63,66), nonpolar/nonpolar thermoplastics (67,68), plastic/rubber and rubber/mbber blends (69,70) have already been reported in the literature. The properties of carbon black filled immiscible PP/epoxy were reported recently by Li et al. (60). The blend system was interesting because one of the components is semicrystalline and the other is an amorphous polar material with different percolation thresholds. The volume resistivity of carbon black filled individual polymers is shown in Fig. 21.23. 

The co-continuous structure and the final rheological properties of an immiscible polymer blend are generally controlled by not only the viscoelastic and interfacial properties of the constituent polymers but also by the processing parameters. For example, the effect of plasticizer on co-continuity development in blends based on polypropylene and ethylene-propylene-diene-terpolymer (PP/EPDM), at various compositions, was studied using solvent extraction. The results showed more rapid percolation of the elastomeric component in the presence of plasticizer. However, the same fuUy co-continuous composition range was maintained, as for the non-plasticized counterparts (Shahbikian et al. 2011). It was also shown that the presence of nanoclay narrows the co-continuity composition range for non-plasticized thermoplastic elastomeric materials (TPEs) based on polypropylene and ethylene-propylene-diene-terpolymer and influences their symmetry. This effect was more pronounced in intercalated nanocomposites than in partially exfoliated nanocomposites with improved clay dispersion. It seems that the smaller, well-dispersed particles interfere less with thermoplastic phase continuity (Mirzadeh et al. 2010). A blend of polyamide 6 (PA6) and a co-polyester of... 

PE is a semi-crystalline (degree of crystallinity depends on number of branches), non-polar polymer which is immiscible with nearly all thermoplastics. About 40 wt% of all thermoplastics are based on PE. Table 2.2.1 lists different types of PE that are commercially available. Important copolymers, blends and other PE derivatives are listed in Table 2.2.2. 

Different monomers may be copolymerized to modify the properties of thermoplastics. For the same purpose, homo- and copolymers are frequently mixed with other substances, including other polymers, various fillers, and nanofillers. The presence of comonomers in macromolecules, as well as interactions between macromolecules in miscible blends, can affect both crystallization and morphology of the polymeric material. Interfaces and the confinement of polymer chains within a finite volume influence the solidification and morphology of immiscible polymer blends and polymer-based composites. They are also of special importance in ultra-thin polymer layers where the thickness is comparable to or smaller than the lamellar crystal thickness itself... 

---