To decrease the amount of plastic waste, the use of recycling techniques become a necessity. However, numerous recycling cycles result in the mechanical, thermal, and chemical degradation of the polymer, which leads to an inefficient use of recycled polymers for the production of plastic products. In this study, the effects of recycling and the improvement of polymer performance with the incorporation of an additive into recycled polypropylene was studied by spectroscopic, rheological, optical, and mechanical characterization techniques. The results showed that after 20 recycling steps of mechanical processing of polypropylene, the main degradation processes of polypropylene are chain scission of polymer chains and oxidation, which can be improved by the addition of a stabilizing additive. It was shown that a small amount of an additive significantly improves the properties of the recycled polypropylene up to the 20th reprocessing cycle. The use of an additive improves the rheological properties of the recycled melt, surface properties, and time-dependent mechanical properties of solid polypropylene since it was shown that the additive acts as a hardener and additionally crosslinks the recycled polymer chains.

In this research, the influences of the addition of PVP to PVDF-HFP polymers and the preparation of thin films using a solvent casting method were studied. The PVDF-HFP and polymer blend PVDF-HFP/PVP thin films with a nanostructured surface were investigated using scanning electron microscopy, differential scanning calorimetry, nanoindentation, and dielectric spectroscopy. The results showed that the PVP formed a dispersed phase (the poorer conductive islands) in the PVDF-HFP polymer matrix, which reduced its mechanical properties. The crystallinity of PVDF-HFP polymer decreased with the addition of PVP by 7.4%, but the PVP induced the formation of the polar β-phase of PVDF-HFP. Therefore, an improved dielectric response is expected, but it was not significantly improved even though the polar β-phase was detected. The contrasting effect was attributed to less conductive PVP islands on the surface of the PVDF-HFP/PVP polymer blend, which decreased its conductivity.

Versatile product protective coatings that deliver faster drying times and shorter minimum overcoat intervals that enable curing at faster line speeds and though lower energy consumption are often desired by coating manufacturers. Product protective coatings, based on silsesquioxane-modified diglycidyl ether of bisphenol-A (DGEBA) epoxy resin, are prepared through a glycidyl ring-opening polymerization using dicyandiamide (DICY) as a curing agent. As silsesquioxane modifier serves the octaglycidyl-polyhedral oligomeric silsesquioxane (GlyPOSS). To decrease the operational temperature of the curing processes, three different accelerators for crosslinking are tested, i.e., N,N-benzyl dimethylamine, 2-methylimidazole, and commercial Curezol 2MZ-A. Differential scanning calorimetry, temperature-dependent FT-IR spectroscopy, and rheology allow differentiation among accelerators’ effectiveness according to their structure. The former only contributed to epoxy ring-opening, while the latter two, besides participate in crosslinking. The surface roughness of the protective coatings on aluminum alloy substrate decreases when the accelerators are applied. The scanning electron microscopy (SEM) confirms that coatings with accelerators are more homogeneous. The protective efficiency is tested with a potentiodynamic polarization technique in 0.5 M NaCl electrolyte. All coatings containing GlyPOSS, either without or with accelerators, reveal superior protective efficiency compared to neat DGEBA/DICY coating.

Filament formulation for FDM is a challenging and time-consuming process. Several pharmaceutical polymers are not feedable on their own. Due to inadequate filament formulation, 3D printed tablets can also exhibit poor uniformity of tablet attributes. To better understand filament formulation process, 23 filaments were prepared with the polymer mixing approach. To yield processable filaments, brittle and pliable polymers were combined. A 20 % addition of a pliable polymer to a brittle one resulted in filament processability and vice versa. Predictive statistical models for filament processability and uniformity of tablet attributes were established based on the mechanical and rheological properties of filaments. 15 input variables were correlated to 9 responses, which represent filament processability and tablet properties, by using multiple linear regression approach. Filament stiffness, assessed by indentation, and its square term were the only variables that determined the filament's feedability. However, the resulting model is equipment-specific since different feeding mechanism exert different forces on the filaments. Additional models with good predictive power (R²_pred > 0.50) were established for tablet width uniformity, drug release uniformity, tablet disintegration time uniformity and occurrence of disintegration, which are equipment-independent outputs. Therefore, the obtained model outcomes could be used in other research endeavours.

The number of commercial products claiming self-cleaning properties is rising and testing of long-term activity and durability of such coatings needs to be addressed more. The time-dependent changes of different characteristics like haze, transparency, and color are essential for transparent glazing materials. Herein, we aimed to examine whether the laboratory results obtained on the Zr-modified-titania-silica (TiZr) self-cleaning materials would translate to larger-scale outdoor-exposed testing. TiZr thin films were deposited via spraying onto float glass window surfaces and exposed into three different environments for 20 months. For comparison, a commercially available active SGG BIOCLEAN^TM glass and standard float glass were simultaneously exposed in the same conditions. It was shown that the self-cleaning property of either a commercial product or TiZr-coated float glass was not considerably effective in real field test conditions, although the previous laboratory tests showed pronounced photocatalytic activity of TiZr thin films. The inclination angle; however, was shown to have a considerable effect on the self-cleaning ability of samples, as did the rain patterns during the testing period. On the other hand, the anti-fogging effect of our TiZr material was very well expressed in controlled laboratory conditions (measuring droplet formation time) as well as in the real outdoor environment.