Synthesis, Modification and Optical Characterization of Co-Cr Layered Double Hydroxide

 Cobalt and chromium based layered double hydroxides (LDHs) have been successfully synthesized by the co-precipitation method at a constant pH of 10. The intercalation of stearic acid (C18H36O2) into CoCr-LDH and preparation of their polymer nanocomposites using two different methods were studied in the paper. The obtained samples were characterized before and after modification by X-ray diffractometry (XRD) and Ultraviolet visible (UV-Vis) spectroscopy. It has been shown that different reaction temperature profoundly affects the band-gaps of inorganic and composite structures.Three optical band gap values (Eg1, Eg2 and Eg3) for the samples obtained before and after modification. Two optical band gap values were estimated in polymer/LDH nanocomposites. The high-value band gaps for CoCr-LDH(100°C)- NBR and CoCr-LDH(100°C)-SA- NBR were determined to be 5.9 eV and 5.7 eV, respectively. The low-value band gaps for CoCr-LDH(100°C)-NBR and CoCr-LDH(100°C)-SA- NBR were determined to be 4.1 eV and 3.25 eV, respectively

Effect of functional groups on the thermal degradation of phosphorus- and phosphorus/nitrogen-containing functional polymers

In the present study the thermal behavior of phosphorus- and phosphorus/nitrogen-containing functional polymers was studied. The polymers were synthesized via oxidative chlorophosphorylation reaction of butadiene rubber and were subsequently subjected to hydrolysis, aminolysis and/or alcoholysis in order to introduce appropriate functionalities. The successful modifications of the polymer and presences of the respective functional groups were determined using Fourier transform infrared spectroscopy. It was found that the product of hydrolysis of the modified butadiene rubber contains acidic groups in its structure while the products of aminolysis and alcoholysis contain both acidic and amine and/or alcohol-derived moieties. The kinetic analyses of the thermal decomposition reaction were evaluated using thermogravimetric analysis and subsequently Friedman and Ozawa–Flynn–Wall methods revealing three-stage degradation process. Calorimetric measurements were performed for the studied polymers, and mass spectrometric analyses were used to identify the decomposition products for phosphorus-containing polymer. The overall results allowed to reveal the influence of the attached phosphorus- and phosphorus/nitrogen-containing functional groups to the thermal degradation of the cross-linked polymers

Magnetic nanocomposites based on phosphorus-containing polymers : structural characterization and thermal analysis

Fabrication of magnetic nanocomposites containing iron oxide nanoparticles formed in situ within a phosphorus-containing polymer matrix as well as its structural characterization and its thermal degradation is reported here. Comparative structural studies of the parent polymer and nanocomposites were performed using FTIR spectroscopy, x-ray diffraction, and atomic force microscopy. The results confirmed the presence of dispersed iron oxide magnetic nanoparticles in the polymer matrix. The formed composite combines the properties of porous polymer carriers and magnetic particles enabling easy separation and reapplication of such polymeric carriers used in, for example, catalysis or environmental remediation. Studies on thermal degradation of the composites revealed that the process proceeds in three stages while a significant influence of the embedded magnetic particles on that process was observed in the first two stages. Magnetic force microscopy studies revealed that nanocomposites and its calcinated form have strong magnetic properties. The obtained results provide a comprehensive characterization of magnetic nanocomposites and the products of their calcination that are important for their possible applications as sorbents (regeneration conditions, processing temperature, disposal, etc)