Plastomer blends

The mechanism of formation of morphology structures in iPP-E-plastomers blends via shear-dependent mixing and demixing was investigated by optical microscopy and electron microscopy. A single-phase stmcture is formed under high shear condition in injection machine after injection, namely under zero-shear environments, spinodal decomposition proceeds and leads to the formation of a bicontinuous phase stmcture. The velocity of spinodal decomposition and the phase separation depend on the molecular stmcture of iPP and E-plastomer components. 

In addition to the properties noted above, the formulation parameter in iPP-E-plastomer blends have a profound influence on the dynamic loading (e.g., vibration) performance. The load limits of the blend for applications in which dynamic stresses are predominant were studied by using the hysteresis measurement method. However, their technical application requires knowledge of critical load values. 

Burr, R. H., "Solprene Plastomer Blends in HDPE Film", Phillips Petroleum Company Bulletin 818-P. 

Polyolefine blends are group of versatile materials, which properties can be tailored to specific applications already at the stage of compounding and further processing. Our previous papers on elastomer/plastomer blends were devoted to phenomenon of co crystallization in isotactic poly-propylene/ethylene-propylene-diene rubber (iPP/EPDM) [1] or surface segregation in low-density polyethylene/ethylene-propylene-diene rubber (LDPE/EPDM) [2, 3] systems. Composition and structure of the materials were related to their properties. Recently, we have described the influence... 

The P transition represents the glass transition temperature (Tg) of the polymer and represents motion or displacement of polymer segments. The y transition results from localized relaxation of polymer chains and is believed to provide the major mechanism for low temperature impact absorption. In well-dispersed PP-plastomer blends, the p transition temperature is generally not a limitation for low temperature impact performance. Figure 7.5 shows that Tg is dependent on the density or comonomer content. 

Four types of PP resins are available commercially homopolymer, random copolymer, impact copolymer, and reactor TPO. Homopolymer polypropylene (HPP) is the most difficult to impact enhance. All other types of PP are easier to modify because they contain varied amounts of ethylene linkages or ethylene-propylene bipolymers that reduce the stiffness of the base resin and increase its impact resistance. These structures also provide some degree of compatibility with -f ethylene-alpha olefin plastomers. Basic studies conducted using HPP in polypropylene-plastomer blends illustrate principles that apply to other types of PP as well. 

Figure 7.12 Effect of compounding method/mixing intensity on impact energy of PP-plastomer blends.

Figure 7.14 shows a low-voltage scanning electron micrograph (LVSEM) of an HPP-EB Plastomer blend (using 35 MFR homopolymer PP) and a particle... 

Figure 7.14 (a) Morphology and (b) particle size distribution of HPP-plastomer blend. 

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