Vector fluid

M.J. Frits, Two-Dimensional Lagrangian Fluid Dynamics Using Triangular Grids, in Finite-Difference Techniques for Vectorized Fluid Dynamics Calculations (edited by D.L. Book), Springer-Verlag, New York, 1981. 

The vector fluid concept was first suggested for a polyethylene (PE)/polyamide (PA) reactive blending system [12], as mentioned earlier in this chapter. This concept is interesting because it has the potential to provide a compatibilization method for polymers that have no chemical functionalities suitable for copolymer formation during melt blending (e.g. the case of polyolefin and polystyrene). It has been seen that the blends of polyolefin/polystyrene are difficult to compatibilize in situ by simply adding a free radical initiator into the blending process. Usually, flie pre-made block or reactive polymers or copolymers, which can be expensive, are needed for polyolefin/polystyrene compatibilization [15-17]. If a suitable vector fluid can be found for the polyolefin/ polystyrene/peroxide in situ compatibilization, the process could become more controllable and more cost efficient. 

The vector fluid concept suggests that, during melt Mending of polymers, some of the material used as the vector fluid locates preferentially at the interface between different polymer phases. The reactive ingredient, which is the peroxide and/or initial free radicals formed from the peroxide in the system, could thus be carried by the vector fluid to the polymer interface or at least lead to some preferential partitioning at that surface. The location of peroxide and vector fluid material in a polymer melt should depend on different physical parameters such as... 

In an attempt to extend the study of this behavior fiirther, the vector fluid effect was evaluated in a polyethylene (PE)/polystyrene (PS)/peroxide/vector fluid melt blending system, using different materials, both high and low molecular weight, as vector fluids [14, 22]. A linear low-density polyethylene (PE) and a polystyrene homopolymer (PS) were blended, with the PS/PE ratio set at 80/20 wt%. The materials tested as the vector fluid are... 

A batch mixer (Haake Buchler Rheocord system 40 with a Rheomix 600, 50 cm capacity) was used for preparing the blends. The peroxide and material used as the vector fluid were dry-blended with PE and PS pellets at room temperature. A total charge of 45 g of the mixture was then fed into Haake mixer and blended at 200 C and 100 rpm for 5 minutes. 

To analyze the veetor fluid effect [22], the surface tension of the vector fluid candidates were estimated for the various PE/PS/peroxide/vector fluid system and compared for their efficiency to form graft copolymer. The interfacial tension data for PE/PS/vector fluid blend systems at 200 °C were calculated using Eq. (9.6). The surface tension data of the polymers and vector fluids were obtained from literature [21]. The spreading coefficient of the vector fluid on dispersed PE particles in PS matrix (referred as... 

Table 9.8 Materials Evaluated as Vector Fluid. Fritm Y. Sun et aL, The Canadian Journal of Chemical Engineering (1997) 75, p. 1-6...

Table 9.9 Interfacial Tension (y) and Spreading Coefficient (A) of Different Materials Evaluated as a Vector Fluid, Comparing with Degree of PS Grafting on PE ([PS g), (Calculated for 200°C, Y(ps/pe) = 4.91 x 10 N/cm). From Y. Sun et al., The Canadian Journal of Chemical Engineering (1997) 75, p. 1-6...

The attraction of this approach is that the use of a special peroxide with a surface active character couples the reactive and vector fluid functions together which, in turn, may help the reaction to occur at the interface. 

The vector fluid velocity v in the centrifuges of Figs. 2a and 2b consists of radial, azimuthal, and axial components w, v, and w. As will be shown in Section III, the radial component is zero, the azimuthal component is approximately equal to the solid body rotational speed rQ, and the axial component is a function of radial position alone. Axial fluid motion is generated inside the spinning rotor by two means. 

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