Blends from Two Amorphous Polymers

Two separate solutions are prepared (same solvents, 5 wt%) from two amorphous polymers (see Table 5.2). 

The solutions are always clear.They are then poured together in varying ratios. A few ml of the initially clear solutions are concentrated by evaporating the solvent in small glass dishes with flat bottoms in a drying oven until a film of the polymer blend forms (solvent not to be removed by distillation ). 

The influence of the solvent can be observed, for example, with a PS/PC-blend CH2CI2 allows a faster evaporation and leads to the expected turbid film consisting of the amorphous components PS and PC. Instead,THF and CHCI3 evaporate slower and, hence, allow the PC to partially crystallize, which results In an opaque film. 

As already mentioned two-phase blends show two glass transition temperatures, which can be ascribed to the components. However, homogeneous blends only have an intermediate glass transition temperature, between those of the components, depending on the composition. 

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Table 5,2 Examples for 1 1 polymer blends from two amorphous polymers ...

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