Rheological basis for a survey of complex and multiphasic polymer systems.

Abstract

The aim of this thesis is to establish a set of correlations between the rheological properties of complexand multiphasic polymer systems and different structural and physicochemical parameters, such asmorphology, nanostructure, miscibility and secondary interactions. For that purpose three differentpolymer systems have been selected: a) Nanocomposites and polymer blend nanocomposites(PBNANOs) b) Semicrystalline polymers containing self-nuclei c) Polymers which contain hydrogenbonds. Some of these systems are complex, because they content two different types of chaininteractions, but are morphologically homogeneous, whereas others are multiphasic. In the case ofnanocomposites and PBNANOs a relationship between rheological parameters and different aspects ofthe different morphologies has been established. A non linear parameter derived from large amplitudeoscillatory shear measurements has been linked to the size of the droplets of immiscible blends and therequirements to obtain a viscoplastic behaviour under continuous shear flow have been disclosed. On thebasis of rheological results, electrically conductive nanocomposites and PBNANOs, adequate asstimulus-responsive membranes, have been elaborated. On the other hand, it has been demonstrated thatrheological studies are unique to detect the presence of self-nuclei in semicrsytalline polymers. Finally,the sensitivity of different rheological techniques to investigate secondary interactions between polymerchains, allowing to calculate the number of hydrogen bonds in particular, has been considered inhomopolymers and miscible and immiscible blends. // The aim of this thesis is to establish a set of correlations between the rheological properties of complexand multiphasic polymer systems and different structural and physicochemical parameters, such asmorphology, nanostructure, miscibility and secondary interactions. For that purpose three differentpolymer systems have been selected: a) Nanocomposites and polymer blend nanocomposites(PBNANOs) b) Semicrystalline polymers containing self-nuclei c) Polymers which contain hydrogenbonds. Some of these systems are complex, because they content two different types of chaininteractions, but are morphologically homogeneous, whereas others are multiphasic. In the case ofnanocomposites and PBNANOs a relationship between rheological parameters and different aspects ofthe different morphologies has been established. A non linear parameter derived from large amplitudeoscillatory shear measurements has been linked to the size of the droplets of immiscible blends and therequirements to obtain a viscoplastic behaviour under continuous shear flow have been disclosed. On thebasis of rheological results, electrically conductive nanocomposites and PBNANOs, adequate asstimulus-responsive membranes, have been elaborated. On the other hand, it has been demonstrated thatrheological studies are unique to detect the presence of self-nuclei in semicrsytalline polymers. Finally,the sensitivity of different rheological techniques to investigate secondary interactions between polymerchains, allowing to calculate the number of hydrogen bonds in particular, has been considered inhomopolymers and miscible and immiscible blends.