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Abstract

Novel synthetic routes or chemical modifications of polymers are beneficial when tailoring material properties at the molecular level. However, the development of new synthetic methods is often time-consuming, requiring extensive studies to establish optimal reaction conditions and identify suitable starting materials. In contrast, composites make use of existing polymers, combining their properties to overcome the limitations of one material by complementing it with another. A popular approach to developing polymeric composites is blending. Blending various polymers can yield materials with enhanced characteristics, including mechanical, thermal, and rheological properties. Thus, blending enables the rapid creation of a wide range of composite materials. In many cases, miscible blends exhibit better material properties than immiscible or partially miscible systems. Understanding the features that lead to stable, miscible blends allows one to avoid forming immiscible blends. This understanding can be achieved by applying fundamental concepts of weak interactions and using predictive tools such as solubility parameters of Flory – Huggins solution theory. Determination of the Hansen solubility parameters (HSP) for amine containing polyolefin (APO), the main focus of the present thesis, allows for the prediction of blend thermodynamic behaviour with various ester group containing polymers. A miscible blend containing APO and polycaprolactone (PCL) was prepared using a melt – blending technique. The rheological and mechanical properties of the blend at various compositions were tested thoroughly. Its miscibility was shown by DSC analysis, and it is attributed to strong interactions between functional groups in the two polymers through, primarily, hydrogen bonds. While various molecular weights and polymer compositions were tested, importantly a new shape-memory material was discovered. Polyamides (PA), another group of polymers capable of hydrogen boding, was tested in melt blending with APO. Blend miscibility was predicted using HSP and Flory-Huggins tools mentioned above. Despite favorable miscibility predictions, intense processing conditions possibly hinder the formation of hydrogen-bonding and chemical resistance of PAs, resulting partially miscible blends. However, useful trends reflecting the miscibility predictions were observed in the thermal and mechanical characterization of the blends. In general APO could serve as a powerful blend component, which can enhance the functionality of polymers such as polyesters and polyamines.