Nanotechnology and nanocomposites are part of nanoscience, which has become one of the main research directions in scientific and technical activities. Polymer nanocomposites present a new type of composite materials that contain inorganic nanoparticles dispersed in various polymer matrices. The combination of nanoparticles as nanofillers and the polymer matrix creates unique polymer nanocomposites with interesting physical properties and various potential applications.
The goal of this master’s thesis was to prepare polymeric nanocomposites in a polymer melt using extrusion and injection molding methods, which represent an economical and environmentally friendly approach to composite preparation, as they avoid the use of solvents and monomers. The polymer matrix of the composite was based on the polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinylpyrrolidone (PVP), respectively. We also used the biocompatible polymer polyamide 11 (PA 11) in combination with PVP. Silica nanoparticles and iron (II) oxalate dihydrate microparticles were used as fillers in the polymeric nanocomposite. Iron oxalate is a relatively new and under- researched material. We were interested in whether the addition of these two components would improve the physico-chemical properties of the composite. To reduce the viscosity of the polymer melt during extrusion, appropriate additives were used.
The prepared polymer composites were further characterized by surface, thermal, and structural analyses. We used nanoindentation, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and a rotational rheometer. We also measured the pH and conductivity of aqueous solution of the sample, thus monitoring the dissolution dynamics of the prepared polymer composites. With rheological measurements, it was found that the viscosity of polymer composites with a PVDF-HFP polymer matrix is significantly influenced by silica nanoparticles, as they stabilize the structure of the polymer matrix, making the polymer chain more rigid. On the other hand, the flow behaviour of composites with a PA 11 polymer matrix was primarily affected by the combination of silica nanoparticles and iron oxalate microparticles. Additionally, all polymer composites exhibited shear-thinning behavior due to the alignment of polymer chains and particles within the polymer matrix in the direction of flow. Nanoindentation measurements showed that the addition of silica and iron oxalate to the polymer nanocomposite increases the elastic modulus and hardness in both polymer matrices. The pH and conductivity measurements showed that polymer composites with a PVDF-HFP polymer matrix create an alkaline solution in water, while those with a PA 11 polymer matrix create an acidic one. The dissolution process of the polymer composites was accompanied by an exothermic reaction.
|
