Uncompatibilized blends

Blends of Saturated Hydrocarbon Elastomers (Uncompatibilized Blends)... 

Evidence of chemical interaction between the mbbers and compatibUizers was demonstrated by extracting the blends with chloroform at room temperamre and examining both soluble and insoluble fractions with Fourier transform infrared (ETIR) spectrometry. The weight of the insoluble fraction of the compatibilized melt blend was more than that in the uncompatibilized blend indicating the formation of (EP-g-MA)-g-CR due to reaction between MA and allylic chlorine of CR. The compounds containing epoxidized EPDM additive were examined by both optical and... 

Examination of the fracture by SEM shows that although there is no interphase adhesion in uncompatibilized blends, adhesion between the phases increased and dispersed domains decreased... 

This drawback can be at least partially eliminated by blending PLLA with other polymers (26-29). In addition, ABS has been used for blending (30). The blends were prepared laboratory mill equipped with a twin-screw. It turned out that uncompatibilized blends of PLLA and ABS have a morphology with big phase size and a weak interface. The blends exhibit poor mechanical properties with low elongation at break and decreased impact strength. 

As a next step, the effect of compatibilization on the foaming behavior will be discussed. While the density can only be slightly reduced by SBM, and remains at a rather high level, the foam structure reveals distinct differences, exemplarily shown for a foaming temperature of 160°C and at a foaming time of 10 s (Fig. 18). As mentioned earlier, the uncompatibilized blend reveals a highly inhomogeneous structure,... 

Tensile deformation of the uncompatibilized blend with 50% PS was characterized by the appearance of several regions of localized stress-whitening in the gauge section without global necking. Fracture occurred at one of these regions at a relatively low strain, about 3.2%. This behavior is characterized as quasi-brittle rather than brittle, because some level of plastic deformation precedes fracture even though the fracture strain is low (Chapter 21). 

Fracture Stress and Strain. Yielding and plastic deformation in the schematic representation of tensile deformation were associated with microfibrillation at the interface and stretching of the microfibrils. Because this representation was assumed to apply to both the core-shell and interconnected-interface models of compatibilization, the constrained-yielding approach was used without specific reference to the microstructure of the interface. In extending the discussion to fracture, however, it is useful to consider the interfacial-deformation mechanisms. Tensile deformation culminated in catastrophic fracture when the microfibrillated interface failed. This was inferred from the quasi-brittle fracture behavior of the uncompatibilized blend with VPS of 0.5, which indicated that the reduced load-bearing cross section after interfacial debonding could not support plastic deformation. Accordingly, the ultimate properties of the compatibilized blend depended on interfacial char-... 

Table 5.3 shows dramatic examples of the stabilization of dispersed phase morphology in the presence of a compatibilizing copolymer. In all examples essentially no change in dispersed phase particle size occurs after annealing under static conditions for up to 90 min. The data shown in this Table 5.3 should be compared with those presented in Table 5.2, where the dispersed phase mean dimensions were presented for similar, uncompatibilized blends. 

Figure 15.7. Instrumented Impact behavior of ABS/PA-6 (50/50) blends top — uncompatibilized blend, bottom — compatibilized blend [Akkapeddi et al., 1993].

Figure 15.8. Morphology of ABS/PA-6 blends (TEM, phosphotungstic acid) top — Uncompatibilized blend (5000X), bottom — Compatibilized blend (10,000X) lAkkapeddi, 1993],...

The calorimetric characteristics of iPP phase of the uncompatibilized blends show that the presence of the SBH dispersed phase leads to a slight increase of the PP temperature of crystallization (Fig. 17.8) (37,38). This result can be interpreted by a slightly increased nucleation rate of PP phase in the presence of SBH dispersed particles. As seen in Fig. 17.8, iPP temperature of crystallization increases drastically in the presence of COPP70 and COPP50. The analysis of the X-ray patterns (38) (Fig. 17.9a and b) and calculated parameters (dm values, degree of crystallinity, crystallite size, and intensity ratio) allows the assumption that PP segments of... 

The viscosity of blends varies not only with the composition but with flow conditions as well, which depend on the temperature and shear rate (20,41,65). A decisive effect on PA/PO rheology is caused by the chemistry of interphase processes (41). Blends of PA with ungrafted PO, or uncompatibilized blends, are characterized by a decreased melt viscosity in comparison with the additive... 

BIMS-NR blends as sidewall components. In many of the applications, the saturated elastomer is considered a polymeric antioxidant for the diene rubber. It is believed that the higher molecular weight polyolefins are better in these applications due to limited interdiffusion and a more stable morphology. Some of the benefits in tensile properties and abrasion resistance of the blends may be due to the interdiffusion of high molecular chains of dissimilar elastomers across the phase interface. Significant advances have been made in modifying the structure of polyolefin elastomers to increase the compatibility to unsaturated elastomers. Tse et al. [50b] have shown that uncompatibilized blends of saturated elastomers and unsaturated elastomers are possible if the former contains substantial amounts (>12%) styrene residues. This is expected to be an important area of development in the future with the advent of new synthesis procedures for polyolefins. 

PAr with low concentration of PO, elastomer, or EVAc Uncompatibilized blends Koshimo et al. 1973... 

PP is antagonistically immiscible with PEST, and when the concentratiOTi of the dispersed phase exceeds 5-10 wt%, compatibilization is necessary. Initially, the uncompatibilized blends were formulated within the low concentration region of the dispersed phase. By the end of 1980s, reactive compatibilization started to dominate the technology. Examples of PP/PEST blends are listed in Table 1.51. 

PPE is not miscible with SMA containing as much as 28 % MA (Witteler et al. 1993). To compatibilize these two resins, Koning et al. (1993b, 1996) have added a monoamine-terminated PS that can form a graft copolymer with SMA. Since the amine-terminated PS is miscible with PPE, compatibilized PPE-SMA blends are obtained. Specifically, 30 parts of unfunctionalized PPE was blended (internal mixer at 220 °C, or mini-SSE at 280 °C, or TSE at 326 °C) with 56 parts SMA (28 % MA) and 14 parts amine-functionalized PS. The blend was characterized by TEM, SEM, mechanical and thermal properties, DMA, and GPC copolymer detection. The effect of pre-reacting amine-terminated PS with SMA was studied. The blend properties were compared to those for uncompatibilized blends. Blends were also made containing ABS -i- SEBS. Eurther examples of compatibilizing copolymer formation in PPE-styrene copolymer blends are shown in Table 5.43. 

Mechanical properties vs. uncompatibilized blend/HDPE grafted with 2-hydroxyethyl methacrylate-isophorone diisocyanate... 

PP-g-MA/amine-terminated PS Extrusion/morphology/varying viscoelastic properties of blend components/comparison to uncompatibilized blend Omonov et al. 2007... 

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