Blend properties

As can be seen from Figure 4, LBVs for these components are not constant across the ranges of composition. An iateraction model has been proposed (60) which assumes that the lack of linearity results from the iateraction of pairs of components. An approach which focuses on the difference between the weighted linear average of the components and the actual octane number of the blend (bonus or debit) has also been developed (61). The iadependent variables ia this type of model are statistical functions (averages, variances, etc) of blend properties such as octane, olefins, aromatics, and sulfur. The general statistical problem has been analyzed (62) and the two approaches have been shown to be theoretically similar though computationally different. 

For some blends, properties exceeding additive or those of either component can be achieved (109,152,158). The curve labeled synergistic in Figure 6 illustrates this case. 

The treatment of blends as a two phase system opened up an interesting field of modifying the composite properties by the use of a (third component within the interface boundaries, which is termed as compatibilizers [1]. Such modifications are still being extended to the formation of microgel out of the interaction between the two blend partners having a reactive for functionalities. This type of interchain crosslinking does not require any compatibilizer to enhance the blend properties and also allows the blends to be reprocessed by further addition of a curative to achieve still further improved properties [3,4]. Such interchain crosslinking is believed to reduce the viscoelastic mismatch between the blend partners and, thus, facilitates smooth extrusion [5,6]. 

The two generic terms found in the blend literature are compatibility and miscibility. Components that resist gross phase segregation and/or give desirable blend properties are frequently said to have a degree of compatibility even though in a thermodynamic sense they are not miscible. In the case of immiscible systems, the overall physicomechanical behavior depends critically... 

All this is related to the distinction between chemical and physical properties. Physical properties describe what a body is, as it is now. Chemical properties describe what a body can become, how it can react with other identifiable bodies. When bodies mix physically their properties blend properties common to both may be intensified, others are more or less cancelled out or diluted, but the original properties are still there in the mix. Black and white paint can be mixed to any shade of grayness some shades might be distinctive enough to be given names, but there are no sharp boundaries. 

Effect of Plasma-Coated Silica on SBR/EPDM Blend Properties... 

The butadiene and butadiene-acrylic monomer systems polymerize when irradiated on PVC or vinyl chloride copolymer latex. The structure of the polymer obtained may be grafted if it can be proved that the copolymer properties are different from the blend properties. To elucidate the structure we studied a copolymer obtained by polymerizing butadiene-acrylonitrile on a PVC homopolymer lattice. Owing to practical reasons and to exclude the secondary effect of catalytic residues we used y radiation. However, we shall observe in a particular case the properties of peroxide-initiated graft copolymer. 

Table 1 presents the feed blend properties for selected periods of PDU Runs 2LCF-10, -12, 13, 14, 16, and -17. Table 2 presents the feed blend properties for PDU Runs 2LCF-20 and -21. 

Feed Blend Properties Solvent Study and Thermal Baseline Study... 

Leaving aside for the moment the relative advantages of immiscible vs. miscible blend systems, it is clear from the brief review above that the blend properties are strongly dependent on their phase structures and on the adhesion between phases. The presence and composition of phases as well as the surface energy of interaction between phases are, in principle, functions of the thermodynamics of interaction between the polymer components of the blend. Consequently, there is a need to be able to predict this interaction. 

Without the Biodiesel Standard, there would be no sustainable biodiesel market. The Biodiesel Standard guarantees that products are properly tested for blend properties, performance in engine use, and functionality with injection systems used in the modern common rail diesel engines. Many car manufacturers state that FAME used in commercial fuel must meet both standard references EN14214, the European Biodiesel Standard, and ASTM D 6751, the U. S. Biodiesel Standard (Table 3.1). Making biodiesel that complies with the applicable Biodiesel Standard helps guarantee the functionality and performance in transport engines. 

Whereas atactic PS is an amorphous polymer with a Tg of 100 CC, syndio-tactic PS is semicrystalline with a Tg similar to aPS and a Tm in the range 255-275 °C. The crystallization rate of sPS is comparable to that of polyethylene terephthalate). sPS exhibits a polymorphic crystalline behavior which is relevant for blend properties. In fact, it can crystallize in four main forms, a, (3, -y and 8. Several studies [8] based on FTIR, Raman and solid-state NMR spectroscopy and WAXD, led the a and (3 forms to be assigned to a trans-planar zig-zag molecular chain having a (TTTT) conformation, whereas the y and 8 forms contain a helical chain with (TTG G )2 or (G+G+TT)2 conformations. In turn, on the basis of WAXD results, the a form is said to comply with a unitary hexagonal cell [9] or with a rhombohedral cell [10]. Furthermore, two distinct modifications called a and a" were devised, and assigned to two limiting disordered and ordered forms, respectively [10]. 

Coherently, as expected for immiscible blends, Tg values measured by DSC show very small variations with respect to the pure components while the mechanical properties degrade with respect to neat sPS. In particular, for minimum polyolefin contents <40 wt%, uniaxial tensile tests revealed a decrease in Young s modulus, elongation at break and energy to break. For higher contents, a phase inversion of the morphology occurs and the blend properties approach progressively those of the pure polyolefins. 

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