BINARY BLEND

Figure B3.6.3. Sketch of the coarse-grained description of a binary blend in contact with a wall, (a) Composition profile at the wall, (b) Effective interaction g(l) between the interface and the wall. The different potentials correspond to complete wettmg, a first-order wetting transition and the non-wet state (from above to below). In case of a second-order transition there is no double-well structure close to the transition, but g(l) exhibits a single minimum which moves to larger distances as the wetting transition temperature is approached from below, (c) Temperature dependence of the thickness / of the enriclnnent layer at the wall. The jump of the layer thickness indicates a first-order wetting transition. In the case of a conthuious transition the layer thickness would diverge continuously upon approaching from below.

Figure 10 Schematics of two-dimensional chain conformations of the block copolymer and the microsphere in a binary blend [36].

We can classify blends into three categories miscible, partially miscible, and immiscible. Miscibility can be defined in thermodynamic terms. For a binary blend to be miscible the following two conditions should be satisfied ... 

The amount of the copolymer to be added into a binary blend depends on several factors. Since the copolymer preparation is an expensive process, it should be used to its maximum efficiency. The amount of copolymer (w) required to saturate a unit volume of blend is given by ... 

Greco et al. [50] studied the effect of the reactive compatibilization technique in ethylene propylene rubber-polyamide-6 blends. Binary blends of polyamide-6-ethylene propylene rubber (EPR) and a ternary blend of polyamide-6-EPR-EPR-g-succinic anhydride were prepared by the melt mixing technique, and the influence of the degree of grafting of (EPR-g-SA) on morphology and mechanical properties of the blends was studied. 

Figure 8 Charpy resilience (R) as a function of test temperature for PA-6 homopolymer and PA-6-EPR binary blends with increasing degree of grafting (DG), 0-0%, -0.6%, A-2.4%, and B-4.5% DG. Source Ref. 61.

De Sarkar et al. [52] have reported a series of new TPEs from the blends of hydrogenated SBR and PE. These binary blends are prepared by melt mixing of the components in an internal mixer, such as Brabender Plasticorder. The tensile strength, elongation at break, modulus, set, and hysteresis loss of such TPEs are comparable to conventional rubbers and are excellent. At intermediate blend ratio, the set values show similarity to those typical of TPEs (Table 5.5). 

The thermal, mechanical, and morphological behaviors of two binary blends, HDPE-E-plastomer (Engage 8200) and iPP-E-plastomer (Engage 8200) have been investigated to compare the compatibility and molecular mechanistic properties of the blends. Both systems are thermodynamically immiscible but mechanically compatible. Thermal studies indicate that both blends exhibit two distinct melting peaks and there is depression of the HDPE melting peak in the blend with high... 

This development was technologically successful and E-plastomers are widely recognized to be very effective impact modifiers for iPP. In initial experiments, binary blends of iPP were compounded with EPDM, E-plastomers, or SEES as the elastomeric phase. In comparison to the known modifiers, such as EPDM or SEES, the binary blends with E-plastomers have properties which strongly depend on the amount and the identity of the E-plastomer. Thus, the addition of... 

Glass transition temperature (Tg), measured by means of dynamic mechanical analysis (DMA) of E-plastomers has been measured in binary blends of iPP and E-plastomer. These studies indicate some depression in the Tg in the binary, but incompatible, blends compared to the Tg of the corresponding neat E-plastomer. This is attributed to thermally induced internal stress resulting from differential volume contraction of the two phases during cooling from the melt. The temperature dependence of the specific volume of the blend components was determined by PVT measurement of temperatures between 30°C and 270°C and extrapolated to the elastomer Tg at —50°C. 

As nuclear reactions are isotope specific, NRA may be used, for example, to distinguish the distribution of binary blends of polymers in a polymer film, where one of the polymers is labelled with deuterium. The depth distribution of the deuterium atoms can be established and hence that of the labelled polymers. 

With the discussion above in mind, it is now possible to provide a similar semi quantitative framework in which to view the results obtained on ternary systems (homopolymer A, homopolymer B, diblock AB) and on binary blends of one homopolymer and a diblock copolymer. Of particular importance is the need for an explanation of the fact that the diblock copolymer may serve either as an emulsifying agent (9,25) or as a homogenizing agent (1, 4 ) in ternary blends. 

Fig.44 TEM image for binary blend of H-shaped (PS-PI)3-PS-(PI-PS)3 with 35 wt% PS stained with 0s04 in bright field mode. From [122], Copyright 2002 Elsevier... 

Fig. 60 Schematic illustration for formation of cylindrical morphology in a blend of slightly asymmetric lower molecular weight PS-b-PI (/3-chain) with large symmetric PS-fc-PI (a-chain). a Molecule of /S-chain with non-zero spontaneous curvature, b Cylindrical morphology formed by neat /3 chains shown in a. Here mean curvature of cylinder (solid line) is larger than spontaneous curvature of /3-chain (dashed lines). c Cylindrical morphology formed by binary blend of /3-chains shown in a and large symmetric copolymers (a-chain). In this case, mean curvature of cylinder closely fits to spontaneous curvature of /3-chain. From [180]. Copyright 2001 American Chemical Society...

Figure 13.3 shows inlet pressure versus flow rate profiles calculated using relationships explained elsewhere.28 A 4.6 mm x 250 mm column packed with particles ranging in size from 1 to 5 /.un was used for each case. The solid lines in the figure represent an eluent of 100% water. The dotted lines above each solid line represent a binary mixture of 60 40 methanokwater, and the dashed lines represent binary blends of 50 50 acetonitrile water. As an example, a column packed with 5 fjm... 

Table 20.5 The blend ratios and weights of each component in the binary blends...

The isothermal crystallization study on binary blends was performed with P(HB80-ET20)/PET (weight ratio, 4 3) and P(HB80-ET20)/PEN (weight ratio, 4 3). The Avrami theory was applied, as shown in the following equation [23, 46] ... 

The morphology of the spherulites was in the form of a Maltese Cross , which was confirmed by the Avrami exponent value in the DSC study. The spherulite size of the binary blends was smaller than that of pure PET and PEN. 

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