| الوصف: |
According to Gibbs, the free mixing energy is decisive for the thermodynamic compatibility of two substances, e. g. polymers. If the free mixing energy is positive, the two mixing partners are separated. For such molecularly immiscible polymers, a finely distributed disperse phase within the matrix can only occur if drop breakage happens during processing. This depends on the strain and shear rates and the capillary number, which must exceed a critical value. If all preconditions are met, coupling agents can be used to improve the phase adhesion of two given polymers and to stabilize the morphology. This is due the reduction of the interfacial tension, thus facilitating drop breakage and simultaneously increasing interfacial tension, which suppresses coalescence. In this work, the effect of three different coupling agents is investigated to evaluate their influences on the property changes in polyamide 6/ethylene-octene-copolymers-blends. It can be shown that the rheological behavior as well as the blend morphology strongly depends to the type and the amount of the used coupling agent. A direct correlation between the rheological behavior and the blend morphology can be assumed but not fully confirmed. For this purpose, the particle size of the soft phase within the matrix is analyzed optically by a scanning electron microscope. Fracture mechanical investigations are carried out to evaluate the blend modifications to the mechanical properties. The results obtained using the method of essential work of fracture shows a significant influence due to the type of coupling agent, but less due to morphology. Therefore, in order to better understand the structural property relationships, the selection of coupling agent is as important as the blend morphology.According to Gibbs, the free mixing energy is decisive for the thermodynamic compatibility of two substances, e. g. polymers. If the free mixing energy is positive, the two mixing partners are separated. For such molecularly immiscible polymers, a finely distributed disperse phase within the matrix can only occur if drop breakage happens during processing. This depends on the strain and shear rates and the capillary number, which must exceed a critical value. If all preconditions are met, coupling agents can be used to improve the phase adhesion of two given polymers and to stabilize the morphology. This is due the reduction of the interfacial tension, thus facilitating drop breakage and simultaneously increasing interfacial tension, which suppresses coalescence. In this work, the effect of three different coupling agents is investigated to evaluate their influences on the property changes in polyamide 6/ethylene-octene-copolymers-blends. It can be shown that the rheological behavior as well as the blend ... |
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