Search results for "CARBONATE"
showing 10 items of 920 documents
The first operating thermolytic reverse electrodialysis heat engine
2020
Abstract Thermolytic reverse electrodialysis heat engine (t-RED HE) has been recently proposed as a technology for converting low-temperature waste heat into electricity. The construction and operation of the first world lab-scale prototype unit are reported. The system consists of: (i) a reverse electrodialysis unit where, the concentration gradient between two solutions of thermolytic salts is converted into electricity and (ii) a thermally-driven regeneration unit where low-temperature heat is used to restore the initial conditions of the two feed streams. Regeneration is based on a degradation process of salts into gaseous ammonia and carbon dioxide, which can be removed almost entirely…
Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-bas…
2014
Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the init…
Liquid phase exfoliation of carbonate-intercalated layered double hydroxides.
2019
Direct exfoliation of a carbonate layered double hydroxide (LDH) has been achieved by using a novel horn-probe sonic tip, avoiding the development of time-consuming anion-exchange reactions. The most suitable solvents were chosen based on the Hildebrand solubility parameters and the thickness of the exfoliated nanosheets confirmed unambiguously the successful delamination.
Facile synthesis of magnetically separable CoFe2O4/Ag2O/Ag2CO3 nanoheterostructures with high photocatalytic performance under visible light and enha…
2017
Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP-2016/7. The authors wish to kindly acknowledge the financial support of HZB, Estonian Research Council (PUT1096, PUT735 and IUT2-25) and Estonian Centre of Excellence in Research Project “Advanced materials and high-technology devices for sustain-able energetics, sensorics and nanoelectronics” TK141 (2014–2020.4.01.15-0011).
Formation of calcium containing minerals in the low temperature dolomite ceramics
2011
In order to elaborate low temperature dolomite ceramics, potentially suitable for the production of building materials, local low carbonate clay and dolomite siftings were used as a raw materials. Relationship between mechanical properties, mineral composition and firing temperature kept in the range of 600-800° C were established. According to the obtained data it was detected that the optimal burning temperature, giving the highest crushing strength (40 MPa) was around 700-750° C, optimal proportion of dolomite and clay expressed as ratio between CaO and Al2O3 - 2.5 wt%. Gradual formation of C3A occurs during firing, yielding C4AHX, i.e. mainly C4AH13 after hydratation of obtained composi…
Shear characterization of CaCO3-filled linear low density polyethylene
1988
Shear properties of CaCO3-filled linear low density polyethylene have been determined over a wide range of filler loading. The viscosity rises with the filler loading especially at low shear rates and a yield value appears for CaCO3-contents larger than 5%. The decrease of the die-swell ratios of the filled samples indicates a reduction of the melt elasticity.
Rheological properties and morphology in LLDPE and PC based blends
1990
Abstract During an interlaboratory project on polymer blends (Technical Working Party-Polymer Blends-VAMAS), the rheological characteristics of some samples of blends of polycarbonate with linear low density polyethylene have been evaluated with the aid of a capillary rheometer. Some morphological observations on the extruded samples have also been performed through SEM and an attempt has been made to correlate the macroscopic and microscopic results.
The effect of introduction of montmorillonite clay (MMT) on the elastic properties of polycarbonate (PC) composition with acrylonitrile-butadiene sty…
2015
Abstract Polycarbonate (PC)/acrylonitrile–butadiene–styrene terpolymer (ABS)/montmorillonite (MMT) nanocomposites have been obtained by melt compounding in a twin-screw extruder. Structural and elastic properties have been characterized. The theoretical analysis of the elastic properties of PC/ABS/MMT composite with a widely varied number of elementary layers in clay filler particles has been performed in order to estimate the influence of the degree of exfoliation of particles on the effect of reinforcement of the material. Results of the theoretical analysis have been compared with the experimental data about the effects of unmodified and two types of organically modified montmorillonite …
The Effect of Calcium Carbonate on the Photo-Oxidative Behavior of Poly(butylene adipate-co-terephthalate)
2020
The aim of this work is to evaluate the influence of nanosized CaCO3 on the photo-oxidation of poly(butylene adipate-co-terephthalate) (PBAT)-based nanocomposites. The PBAT/CaCO3 nanocomposites are prepared by using a corotating twin-screw extruder with 0, 2, and 5 wt% of CaCO3. The films are obtained by film blowing process. Specimens of the nanocomposites and that of the pure polymer are subjected to accelerated aging with a cycle of 8 h of light at a temperature of 55 °C followed by 4 h condensation at 45 °C to evaluate the effects of the CaCO3 addition on the photo-oxidation of PBAT. The results indicate that the modulus and tensile strength of the nanocomposites are increased significa…
Structure, micromechanical and magnetic properties of polycarbonate nanocomposites
2013
The current study evaluates the applicability of polycarbonate (PC) for development of magnetic polymer nanocomposites with CoFe2O4 nanofiller, the amount of which was changed from 0 to 5 wt. %. Ethylene-vinyl acetate elastomer in the amount of 10 wt. % was added as toughener. Upon introduction of the magnetic filler a magnetic hysteresis loop was observed: at 5 wt.% of CoFe2O4 saturation magnetization of the nanocomposite was 2,2 emu/g, remanent magnetization was 0,8 emu/g and coercivity is 1200 G. Nanoindentation tests showed that nanofiller-reinforced samples maintain reasonable plasticity characterized by work of plastic indentation, while their modulus and hardness were improved by up …