Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation
of the thermal behaviour and structure of the complexes Mg(pc)(na)3⋅3H2O (I), Mg(pc)(py)2⋅2H2O (II),Mg(pc)(pic)2⋅2H2O (III) and Mg(pc)(caf)2⋅4H2O (IV), where pc=2,6- pyridinedicarboxylate, na=nicotinamide,py=pyridine, pic=γ-picoline and caf=caffeine. The thermal decomposition of these compounds is multi-stage processes. The chemical composition of the complexes,
the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and
complexometric titration. Schemes of destruction of these complexes are suggested. Heating of these compounds first resulted
in a release of water molecules. In complexes I, II and IV the loss of the molecular ligands (na, py and caf) occur (on the
TG curves) in one step (-2na, -2py and -2caf) and in complex III in two steps (-pic, -pic). The final product of the thermal
decomposition was MgO. The thermalstability of the complexes can be ordered in the sequence: IV<I<III<II. Nicotinamide, pyridine,
γ-picoline and caffeine were co-ordinated to Mg(II) through the N atom of the respective heterocyclic ring. IR data suggested
a unidentate co-ordination of carboxylates to Mg(II) in complexes I–IV.
The system of sulfoaluminate ferrite belite (SAFB) clinkers premixed with Portland cement (PC) in mass ratio 85:15 in combination
with hydroxypropylmethyl cellulose (HPMC) or polyphosphates(poly-P) was used for the syntheses of Macro-Defect-Free (MDF)
materials. The subsequent moisture treatment and thermal stability of these MDF materials were investigated. The effect of
individual humidity upon the evolution of mass is more intensive than the effects of composition of MDF materials or duration
of the original MDF material synthesis. Detailed values of mass changes at 100% relative humidity (RH) and under ambient conditions
are strongly affected by the nature of polymer used. A significant improvement of moisture resistance of MDF materials is
achieved when the materials are dried after 24 h of finishing the pressure application. In the inter-phase section of MDF
material samples, the content ofC-(A,F)-S hydraulic phases, mainly tetracalcium aluminate ferrite monosulphatehydrate (AFm) decomposing by 250°C and CaCO3 decomposing at 600–700°C increase after the moisture attack, while cross-links in AFm-like section with typical thermoanalytical
traces in temperature region 250–550°C remain intact.
This research provides a fundamental understanding of the early stage hydration of Portland cement paste, tricalcium aluminate
(C3A) paste at water to cement ratio of 0.5 and C3A suspension at water to cement ratio of 5.0 modified by 2 or 4 mass% of sodium carbonate. A high conversion of unreacted
clinker minerals to gel-like hydration products in the cement-Na2CO3 pastes takes place rapidly between 1st to 24th h. Contrary the Ca(OH)2 formation within the same time interval is retarded in the excess of CO32− ions due to intensive rise and growth of CaCO3 crystals in hydrated cement. Later, the conversion of clinker minerals to the hydrate phase is reduced and higher contents
of calcite and vaterite relative to that of Ca(OH)2 in comparison with those found in the Portland cement paste are observed. As a consequence a decrease in strength and an
increase in porosity between hardened Portland cement paste without sodium carbonate and those modified by Na2CO3 are observed. C3A hydrates very quickly with sodium carbonate between 1st and 24th h forming hydration products rich in bound water and characterized also by complex salts of (x)C3A�(y)CO2�(zH2O type, whereas C3A-H2O system offers C3AH6 as the main hydration product. Higher content of the formed calcium aluminate hydrates in C3A-Na2CO3-H2O system also contributes to early strength increase of Portland cement paste.
Crushing or otherwise processing potato and subsequent mild washing of the pulp produces mostly granular and fibrous starch.
These fibers are experimental carrier material for microbes in bioremediation of polluted waters. This method offers the benefit
of increasing the exposure of the microbes to the pollutant by increasing their residency within the site. Because of the
physical nature of the material, it also offers the possibility of carrying, in addition to the microbes, essential macronutrients
such as nitrogen and phosphorous that would be limited in availability in contaminated waters. We have previously reported
on the physical nature of these fibers through thermal analysis and on their ability to bind/aggregate bacteria. We have extended
that study in this report by infusing the fibers with a source of nitrogen and phosphorous, namely ammonium phosphate. The
TG curves for ammonium phosphate-infused white and sweet potato fibers exhibited three main mass loss steps corresponding
to the three exothermic DTG peaks. Infusion with the ammonium phosphate salt also affected the bacterial binding/aggregation
capacities. The range of their binding capacities decreased to a range of 26.9–43.3% compared to untreated fibers.
Several calcium silicate hydrate (C–S–H)-polymer nanocomposite
(C–S–HPN) materials have been prepared by incorporating poly(acrylic
acid) (PAA) into the inorganic layers of C–S–H during precipitation
of quasicrystalline C-S-H from aqueous solution. The synthetic C–S–HPN
materials were characterized by X-ray fluorescence (XRF), X-ray diffraction
(XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy/energy
dispersive spectroscopy (SEM-EDS), thermogravimetry (TG), differential thermogravimetry
(DTG) and differential scanning calorimetry (DSC). The XRD peaks of C–S–HPN
materials suggest the intermediate organizations presenting both intercalation
of PAA and exfoliation of C–S–H. The SEM images of C–S–H
and C–S–HPN materials with different PAA contents exhibit the
significant differences in their morphologies. Effects of the material compositions
on the thermal stability of series of C–S–HPN materials along
with PAA and C–S–H has been studied by TG, DTG and DSC. Three
significant decomposition temperature ranges were observed on the TG curves
of all C–S–HPN materials.
A series of calcium silicate hydrate (C–S–H)-polymer nanocomposite
(C–S–HPN) materials were prepared by incorporating poly(acrylic
acid) (PAA) into the inorganic layers of C–S–H during precipitation
of quasicrystalline C–S–H from aqueous solution. The as-synthesized
C–S–HPN materials were characterized by X-ray fluorescence (XRF),
X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy
(SEM-EDS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric
analysis (TG) and differential scanning calorimetry (DSC). The XRD analysis
of C–S–HPN materials suggest the intermediate organizations presenting
intercalation of PAA within C–S–H and exfoliation of C–S–H.
The SEM micrographs of C–S–H, PAA and C–S–HPN materials
with different PAA contents exhibit the significant differences in their morphologies.
The effect of the material’s composition on the thermal stability of
a series of C–S–HPN materials along with PAA and C–S–H
were studied by TG, DTA and DSC. Three significant decomposition temperature
ranges were observed on the TG curves of all C–S–HPN materials.
A series of calcium silicate hydrate (C-S-H)-polymer nanocomposite (C-S-HPN) materials were prepared by incorporating poly(vinyl
alcohol) (PVA) into the inorganic layers of C-S-H during precipitation of quasicrystalline C-S-H from aqueous solution. The
as synthesized C-S-HPN materials were characterized by Fourier-transform infrared photoacoustic (FTIRPAS) spectroscopy, X-ray
diffraction (XRD), scanning electron microscopy/energy dispersed spectroscopy (SEM/EDS), thermogravimetric analysis (TG),
differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The XRD peaks of C-S-HPN materials suggest
the intermediate organizations presenting both intercalation of PVA and exfoliation of C-S-H. The SEM micrographs of C-S-H,
PVA and C-S-HPN materials with different PVA contents exhibit the significant differences in their morphologies. Effects of
the material compositions on the thermal stability of a series of C-S-HPN materials along with PVA and C-S-H were studied
by TG, DTG and DSC. Three significant decomposition temperature ranges were observed in the TG curves of all C-S-HPN materials.
Metal carboxylato-hydrazinates are very good precursors for the synthesis of metal as well as mixed metal oxides as these
decompose to nanosized oxides with high surface area most of the times at comparatively lower temperatures. In the present
study one such novel precursor nickel manganese fumarato-hydrazinate (NiMn2(C4H2O4)3·6N2H4) has been prepared and characterized by XRD, FTIR and chemical analysis. The thermal decomposition of the precursor has also
been studied by isothermal, differential thermal and thermogravimetric analysis. The precursor shows two-step dehydrazination
followed by decarboxylation to form NiMn2O4. The infrared spectra show N-N stretching frequency at 965 cm−1, which confirm the bidentate bridging hydrazine. XRD confirms the formation of single phase NiMn2O4.