Development of the Vector Fluid Compatibilization Concept

The efficiency of an interfacial reaction between PE and PS is an overall result of chemical and thermodynamic behaviors of the materials during processing. 

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 

The distribution pattern of a low molecular weight additive in a blend is difficult to detect directly using a conventional sample preparation process for electron microscope observation. 

For example, the sample surface for electronic microscope observation is prepared by mechanically breaking or cutting of raw sample, followed by further treatment of the fresh surface of the sample. During such a process, the sample surface must bear the mechanical shock at low temperature, the vacuum and coating at room temperature, and the electron beam. It is easy to understand that the particles of low molar mass material on the sample surface can be lost during the sample preparation. However, with polymer components, it is possible to detect their distribution using normal SEM sample preparation. 

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