The aim of this work was to study the influence of calcium carbonate nanoparticles in both tensile and impact mechanical properties of a polypropylene homopolymer. Four compositions of PP/CaCO3 nanocomposites were prepared in a co-rotational twin screw extruder machine with calcium carbonate content of 3, 5, 7 and 10 wt. (%) The tests included SEM analyzes together with EDS analyzer and FTIR spectroscopy for calcium carbonate, tensile and impact tests for PP and the nanocomposites. The results showed an increase in PP elastic modulus and a little increase in yield stress. Brittle-to-ductile transition temperature was reduced and the impact resistance increased with the addition of nanoparticles. From the stress-strain curves we determined the occurrence of debonding process before yielding leading to stress softening. Debonding stress was determined from stress-strain curves corresponding to stress in 1% strain. We concluded that the tensile properties depend on the surface contact area of nanoparticles and on their dispersion. Finally we believe that the toughening was due to the formation of diffuse shear because of debonding process

Mixed matrix membranes are promising options for improving gas separation processes. Zeolitic imidazolate frameworks (ZIFs) have a porous structure similar to conventional zeolites, being capable in principle of separating gases based on their differences in kinetic diameter while offering the advantage of having a partial organic character. This partial organic nature improves the compatibility between the sieve and the polymer, and a combination of the mentioned characteristics makes these hybrid materials interesting for the preparation of mixed matrix gas separation membranes. In this context the present work reports the preparation of Ultem^®/ZIF-8 mixed matrix membranes and their permeabilities to pure CO₂, N₂ and CH₄gases. A significant increase in permeability with increase in CO₂/N₂ selectivity was observed for the mixed matrix systems as compared to the properties of the neat Ultem^®. Sorption results allowed to speculate that the ZIF-8 framework is not completely stable dimensionally, what influences the separation process by allowing gases with higher kinetic diameter than its nominal aperture to be sorbed and to diffuse through the crystal. Sorption and diffusion selectivities indicate that the higher separation performance of the mixed matrix membranes is governed by the diffusion process associated with the influence of gas molecule's geometry.

The aim of this work was to study the influence of calcium carbonate nanoparticles in crystallization process of polypropylene. Four compositions of PP/CaCO3 nanocomposites were prepared in a co-rotational twin screw extruder machine with calcium carbonate content of 3, 5, 7 and 10 wt. (%). The tests included SEM analyzes for calcium carbonate, differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) for the nanocomposites. The results showed an increase in PP crystallization temperature and crystallinity degree, and a reduction in spherullites size. The formation of PP β phase was confirmed by DSC and WAXD results. Finally from DSC analyses under isothermal conditions it was confirmed that calcium carbonate nanoparticles have a nucleation effect in polypropylene crystallization process by reducing the half crystallization time and increasing the kinetic constant (k)

This study focuses on optimizing the synthesis parameters of ZIF-67 by using the hydrothermal method and assessing the hydrothermal stability of the resulting hierarchical structures. The primary goal is to evaluate their structural integrity in aqueous environments, which is crucial for applications such as gas separation membranes. The optimization process involved dissolving 2-methylimidazole (MeIM) and the surfactant CTAB at controlled temperatures while vigorously stirring to promote micelle formation, followed by the addition of the metal precursor. This resulted in ZIF-67 particles with improved crystallinity and a more uniform morphology. Hydrothermal stability tests showed that ZIF-67 synthesized without CTAB was more resistant to structural degradation when exposed to water compared to the samples containing the surfactant. These results highlight the importance of synthesis conditions in enhancing the stability of ZIF-67, demonstrating its potential for gas separation applications, particularly CO₂ capture.