Presence Of Talc Research Articles

Gel Polymer Electrolytes with Talc as a Natural Mineral Filler and a Biodegradable Polymer Matrix in Sodium-Ion Batteries.

A gel polymer electrolyte based on poly(vinyl alcohol) (PVA) is used in sodium-ion batteries (SIBs). The use of biodegradable and water-soluble polymer potentially reduces the negative environmental impact. The other components include sodium salt (NaPF6 ), sulfolane (TMS) as a plasticizer and talc. For the first time, natural and abundant talc has been used as an inert filler in a gel polymer electrolyte. The best results were obtained for moderate amounts of filler (1 and 3 wt%). Then, an increase in the conductivity, transference numbers, and thermal stability of the membranes was observed. Moreover, the presence of talc had a positive effect on the cyclability of the hard carbon electrode. The discharge capacity after 50 cycles of HC|1 % T_TMS|Na and HC|3 % T_TMS|Na was 243 and 225 mAh g-1 , respectively. The use of talc in gel polymer electrolytes containing sodium ions improves the safety and efficiency of SIBs.

Microstructure and elemental analysis of iron-based powder composite materials

This paper studies the kinetics of structure formation of an iron-bronze composite containing solid lubricants. Depending on the compacting pressure and sintering temperature, binary and complex phases are detected in the iron-bronze structure. The presence of solid lubricants in the composition of the composite material significantly reduces interaction of the liquid (bronze) and solid (iron) phases during sintering. Talc and graphite, which are heat–resistant at a sintering temperature of 850 – 1150 °C, were used as solid lubricants. The presence of talc, located on the surface of compressed particles of iron, copper, tin and graphite, significantly reduces the effect of their interaction. At the same time, the micro-talc particles envelop them, and its thermal stability retains this state up to high temperatures (approximately 900 °C). It was established that there is no perlite in the microstructure of iron-bronze sintered at a temperature of 850 °C. This can be explained by the talc adsorbing ability on the surface of iron particles which prevents diffusion of carbon into the iron crystal lattice. An increase in the sintering temperature up to 1000 °C leads to the formation of perlite in the iron-bronze structure, while the amount of perlite predominates over ferrite. This indicates the partial burnout of talc from the surface of iron particles and the opening of diffusion paths to carbon. At a sintering temperature of 1150 °C, perlite and a grid of light inclusions are formed in the microstructure of the iron-bronze samples. According to the results of electron microprobe analysis, the light inclusions are solid solutions of variable compositions such as Fe – Cu – Sn, Cu – Fe – Sn, Cu – Sn – Fe. In order to confirm these assumptions, a phase X-ray diffraction analysis was performed. Diffraction patterns of these samples are represented by reflections of iron and copper crystals. The absence of diffraction effects (characteristic of tin crystals) is conditioned by tin solubility in the copper lattice. This is due to the low melting point of tin (232 °C) and its ionic radius, which allows isomorphically replacing of copper and iron ions with tin ions (their difference is less than 15 %).

High‐Pressure Mechanical Properties of Talc: Implications for Fault Strength and Slip Processes

AbstractThe hydrous mineral talc is stable over a relatively large P‐T field and can form due to fluid migration and metamorphic reactions in mafic and ultramafic rocks and in faults along plate boundary interfaces. Talc is known to be one of the weakest minerals, making it potentially important for the deformation dynamics and seismic characteristics of faults. However, little is known about talc's mechanical properties at high temperatures under confining pressures greater than 0.5 GPa. We present results of deformation experiments on natural talc cylinders exploring talc rheology under 0.5–1.5 GPa and 400–700°C, P‐T conditions simulating conditions at deep faults and subducted slab interface. At these pressures, the strength of talc is highly temperature‐dependent where the thermal weakening is associated with an increased tendency for localization. The strength of talc and friction coefficient inferred from Mohr circle analysis is between 0.13 at 400°C to ∼0.01 at 700°C. Strength comparison with other phyllosilicates highlights talc as the weakest mineral, a factor of ∼3–4 weaker than antigorite and a factor of ∼2 weaker than chlorite. The observed friction coefficients for talc are consistent with those inferred for subducted slabs and the San Andreas fault. We conclude that the presence of talc may explain the low strength of faults and of subducted slab interface at depths where transient slow slip events occur.

Evaluation of synergic methods for corrosion protection of reinforced steel

PurposeThis study aims to evaluate the effect of pH on the reinforced concrete steel protection for rebars coated with paint formulations containing talc and free from it. As the presence of talc in paints can offer high pH which cordially affects the protection behavior of the coated rebars. Additionally, this study includes evaluating the durability of concrete mixes in presence of some replacements of ordinary cement such as meta-kaolin (MK) and ground granulated blast furnace slag (GGBFS).Design/methodology/approachTwo paint formulations were prepared containing the same ingredients except that (P1) is free from talc and (P2) contains talc. The anticorrosive behavior of painted steel in the blended concrete mixes containing MK and GGBFS was studied by using different electrochemical techniques in chloride solution. The concrete durability was evaluated by the means of compressive and bond strength beside chloride permeability. Different concrete mixes containing mineral groups or pozzolanic materials were prepared by replacing (10, and 30%) GGBFS and (5, 10 and 15%) MK as binary from cement CEM I with (w/b) 0.45 with superplasticizer ratio (SP) 2% of the binderFindingsIt was found that the presence of talc, in spite of its ability to offer high pH, has affected positively the corrosion behavior of reinforced concrete steel by forming a complex with concrete even if it is present in paint formulation and not free in the medium.Originality/valueThe results revealed that concrete blended with (30% GGBFS and 10% MK) with coated rebars with P2 containing talc showed the highest corrosion protection performance in addition to modified permeability and compression resistance.

Evaluation of the Quality of Bath Cosmetics in Powder Form Depending on the Selection of Fillers

Abstract The aim of the study was to evaluate the effects of hydrophilic microcrystalline cellulose, hydrophobic talc and mixtures of cellulose and talc when used as fillers in powdered bath cosmetics. A number of model formulations were developed that contained fillers in different compositions. Prototypical formulations were prepared and evaluated for their functional properties and skin-drying effect. An increase in the concentration of talc was found to reduce the ability of the formulations to emulsify fatty soils and, consequently, decrease the skin-drying effect after washing. Another result of the study is that a high content of talc does not significantly impair the foaming ability, and the presence of talc improves the stability of generated foam.

Production and characterization of thermoplastic elastomer foams based on the styrene–ethylene–butylene–styrene (SEBS) rubber and thermoplastic material

Abstract Thermoplastic elastomer foams based on styrene–ethylene–butylene–styrene (SEBS)/polypropylene (PP) were produced by using different processing techniques such as extrusion and injection molding to achieve optimized mechanical and thermal properties in terms of strength, elongation, and damping capability. Foaming is a method of introducing gas-filled cells into the material and it is considered an effective way to meet the requirements for higher impact resistance with low density and relatively low hardness. In this study, microspheres were used as a foaming agent and were introduced to the system by using an injection molding machine. They were used in different percentages and ranged from 1 and 3%. They decrease the density of the product thereby lowering the weight and cost. Besides improving damping abilities and decreasing the density, inorganic fillers such as talc, silica, and calcium carbonate were used to increase the mechanical strength, and their effectivity was also investigated. It was observed that a higher amount of foaming agent lowered the density by creating voids in the blend, as expected. The introduction of fillers increases the mechanical properties; however, the density had a negative effect even in the presence of foaming agents. About 3% density reduction can be achieved in the presence of talc and a foaming agent whereas the other fillers had an opposite effect on the density. Accordingly, the impact resistance was affected negatively because of the stiffness of the filler materials, and the highest Izod impact value was 50.2 kJ/m2. The elastic modulus values for foamed samples and filled with CaCO3, talc, and silica were 808, 681, and 552 MPa respectively. Combining foaming and thermoplastic elastomers (TPEs) offers a wide variety of possibilities to new and existing applications. In addition to low hardness and density, foaming provides better damping ability thanks to its morphological structure.

The effect of the hybrid multi-layered Graphene oxide/Talc as a hydrophobic agent in epoxy coating

ABSTRACT Multi-layered Graphene oxide (MLGO) were modified with Talc to prepare a hydrophobic corrosion resistance agent for epoxy through three different methods. The humidity and salt spray tests after 360 and 500 h, respectively, showed the higher performance of the sample prepared by the reflux method compared to the heater-stirrer and microwave method. The results of the FT-IR showed that in the presence of Talc, some of the oxygenated functional groups on MLGO were decreased. Also, the comparison of the experimental tests of the coatings containing 1%wt of MLGO/Talc with the different ratios of MLGO and Talc showed the best results for MLGO/Talc (1:5). The impedance modulus of MLGO–Talc, MLGO and Talc epoxy coatings at the end of two months of immersion were 1.45 E+07, 1.38 E+06 and 6.72E+05 Ω cm2, respectively. So by the reflux method, a hydrophobic MLGO/Talc structure was obtained that was confirmed by the contact angle test.

A New Flame AAS Application for Magnesium Determination in Solid Pharmaceutical Preparations as an Active Ingredient and an Excipient

Objective: A new application of Atomic Absorption Spectroscopy (AAS) has been carried out to determine magnesium in its solid preparations (effervescent and uncoated compressed tablets) as an active ingredient and/or excipient.
 Methodology: The linear range of magnesium was determined. A sample of magnesium effervescent tablets was analyzed. Magnesium stearate concentration was also indirectly determined in commercial paracetamol tablets using two digestion methods. Finally, a sample of drug-free tablets (only contain excipients) was analyzed to study the effect of talc on total magnesium content of the sample.
 Results: Linear range was observed in concentrations between 0.08-0.40 ug/mL of magnesium. Effervescent tablets samples were recovered in the range between 98.66-103.00% which indicates that the product meets specifications. For paracetamol tablets, the content of magnesium stearate was in average of 0.2% and there is no differences between the two digestion methods (t=0.454). Our work on the drug-free sample proved a significant increase of magnesium concentrations in the presence of talc.
 Conclusion: The AAS method is a simple and rapid technique that can be employed for the simultaneous estimation of magnesium in in-process and final products analyses.

Thermal Stability and Flame Resistance of the Coextruded Wood-Plastic Composites Containing Talc-Filled Plastic Shells

Talc is a popular filler for the fabrication of plastic composites. The presence of talc helps improve mechanical, thermal, and flame resistance properties of the composite. In this work, we report the influence of a talc-filled plastic shell layer on thermal stability and fire flammability of the core-shell structured wood high-density polyethylene (HDPE) composites manufactured through coextrusion. The result showed that morphological analysis of the char layer after combustion confirmed the formation of a continuous surface char layer with talc addition in the composites, helping block fire penetration and enhance overall fire resistance of the composites. The shell thickness averaged at 1.0±0.2 mm, which represents a fair thick shell over a 10 mm thick WPC core layer. The surface of regular wood-filled HDPE showed large cracks, allowing more rapid fire penetration and reducing its fire resistance. At 800°C, average residual weight for all composite was 21.5±13.8%, most of which was attributed to the inorganic nonvolatile talc components. With the increase of talc level, THR values of coextruded WPC decreased from 302.47 MJ/m2 (5 wt% of talc) to 262.96 kW/m2 (50 wt% of talc). When talc content in the shell layer was less than 25 wt%, the flame resistance properties were slightly enhanced compared with the composites containing unmodified HDPE shells. When talc content in the shell exceeded 25 wt%, the composite’s total heat release and its rate substantially decreased.

Evidences of talc-white mica assemblage in low-grade metamorphic rocks from the internal zone of the Rif Cordillera (N Morocco)

Talc-phengite intergrowths were identified in epizone rocks from the Beni Mezala unit (Internal Zone of the Rif). These rocks show the non-common assemblage quartz-K-feldspar-albite-phengite-talc-vermiculite-chlorite/vermiculite mixed-layers. Although X-ray diffraction patterns indicate the presence of talc, talc could not be observed petrographically. In contrast, transmission electron microscopy indicates that white mica consists of nanometer-sized intergrowths of phengite and talc. At the scanning electron microscope scale, these micas show anomalously high contents of Fe + Mg composition (with an average value of 0.51 atoms per formula unit, apfu). The subtraction of the talc component from the mica formula allowed to obtain a mica with a limited phengitic substitution K0.91Na0.03(Al1.74 Fe2+0.23Mg0.03Ti0.03)Σ=2.03(Si3.18Al0.82) which permits an estimation of minimum pressure (P) <4 kbar. This is coherent with the medium-P facies series determinate by the b-cell parameter of white micas (9.036 Å). The detailed study at nanometer scale shows a domain structure of talc within the white mica packets probably originated by exsolution from a metastable precursor mica with high Fe + Mg contents. This has been interpreted as a relic of a HP assemblage in a low-grade metamorphic context. The study at nanometer scale should be considered as they may have petrological implications.

The influence of binary pozzolanic replacements on the durability and corrosion performance of reinforced concrete

Purpose The purpose of this research is to study the physical and mechanical properties beside the durability of concrete as well as corrosion resistance of reinforced concrete by replacing Ordinary Portland cement (OPC) with different ratios of silica fume and meta-kaolin and applying two paint formulations to enhance corrosion resistance and mechanical properties. In this work, modified concrete mixes containing pozzolanic materials of industrial wastes such as silica fume (SF) with ratios ranging between (0, 10 and 15%) and calcined raw material such as meta-kaolin (MK) with ratios (0, 3, 5 and 10%), were introduced using water binder ratio (w/b) 0.45 to study their effect on the physico-mechanical properties and durability of concrete as well as corrosion protection performance of reinforced concrete. Two paint formulations containing the same ingredients except that one of them is free from talc (G1) and the other contains talc (G2) were applied on the rebars embedded in these modified mixes. Talc is known to offer high pH to the surrounding media. Design/methodology/approach Modified concrete mixes containing the coated reinforced concrete steel with the different paint formulations in presence and absence of talc were tested, and the corrosion behavior was studied using electrochemical impedance spectroscopy (EIS) in 3.5% NaCl, and the concrete mixes were also tested through their compressive strength, chloride permeability, scanning electron microscope/energy dispersive X-ray analysis and bond strength. Findings The results revealed that the hardened reinforced concrete mix containing 10% SF with 5% MK with embedded rebars coated with G2 (paint containing talc) was the best concrete system which offers concrete sustainability besides high corrosion protection performance, i.e. presence of talc in the paints combined with the effect of cement blended with SF and MK showed positive effect on the reinforced concrete properties that leads to more durability and workability. Originality/value The integrity of using two efficient methods of corrosion protection beside the effect of the different replacements in concrete mixes containing coated reinforced concrete steel with paint formulations free from talc (G1) and others containing talc (G2), which lead to fatal changes in the pH of the surrounding media (i.e. concrete which has high alkaline pH) to achieve good concrete properties aside with convenient paint formulations together.

Influence of talc fillers on bimodal polyethylene composites for ground heat exchangers

AbstractIn this study, a commercial grade of talc is used as filler in a bimodal high‐density polyethylene (HDPE) used for the pressure pipe application. The composites are characterized by thermogravimetric analysis (TGA), differential scanning calorimetry, dynamic mechanical thermal analysis, and tensile testing. The results illustrate that the presence of talc has a considerable effect on the material properties and the pipe life‐length. It is presented that the thermal stability measured by TGA is enhanced, while the oxidation induction time decreases in cooperation of the talc. The nucleation behavior of talc particles during crystallization has no obvious effect on melting temperature; however, an increase in crystallization temperature is evidenced. Storage modulus as recorded from the dynamic mechanical analysis is also increased in all composites, furthermore, the temperature of the α relaxation is shifted toward higher temperature and finally the strain hardening modulus for the HDPE/talc composites is assessed and compared to the neat HDPE as a measure of environmental stress crack resistance.

Comment on 'Metamorphic olivine after dehydration embrittlement in Serpentinite: Case study from the Shiraga Serpentinite mass in the Sanbagawa high P/T metamorphic belt, central Shikoku, Japan' by Fukumura, Okamoto and Terabayashi, https://doi.org/10.1111/iar.12293

Comment on 'Metamorphic olivine after dehydration embrittlement in Serpentinite: Case study from the Shiraga Serpentinite mass in the Sanbagawa high P/T metamorphic belt, central Shikoku, Japan' by Fukumura, Okamoto and Terabayashi, https://doi.org/10.1111/iar.12293

Particle size, distribution, and behavior of talc preparations: within the United States and beyond.

Talc remains a common sclerosant utilized for pleurodesis. However, the use of talc has documented complications and debate has persisted regarding the safety of talc as well as the differences in talc preparations available throughout the world. We sought to describe an up-to-date review of talc preparations available and the impact these preparations may have on the safety profile of talc. Within laboratory-based examinations, talc particle size available within the United States appears to be more consistent with prior reported 'safe' particle sizes. The presence of talc within protein-based solutions appears to modify the overall milieu of the solution and likely results in particle aggregation. The use of talc remains well accepted for pleurodesis as evidenced by inclusion by multiple guidelines. The medical fields' current understanding of talc and its basic interactions within the pleural space remain limited. Multiple questions related to the pleural space and pleurodesis remain unanswered.

Pro-Degradant Effect of Talc Nanoparticles on Polypropylene Films

Fil: Linares, Paula Belen. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Planta Piloto de Ingenieria Quimica. Universidad Nacional del Sur. Planta Piloto de Ingenieria Quimica; Argentina

Synergistic Effect of Talc and Titanium Dioxide on Poly(lactic acid) Crystallization: An Investigation on the Injection Molding Cycle Time Reduction

Injection molding cycle time is one of very important parameters relating to the plastic production rate. In neat poly(lactic acid) (PLA), it requires more than 25 min to obtain its half crystallinity (t1/2). This indicates that the injection molding of neat PLA with high degree of crystallinity (Xc) and high production rate is impossible. This research aims to increase the crystallization rate of PLA by combining two inorganic fillers namely; titanium dioxide (TiO2) and talc. Differential scanning calorimetry (DSC) study indicated that the t1/2 of PLA decreased from 27 min to < 81 s, while the Xc increased by around 16% with the adition of TiO2. Modifying PLA with talc was found to reduce t1/2 down to 36 s and the Xc increased from 0.92 to 20% only at a heating rate of 1 °C/min. The combination of talc and TiO2 was significantly increased the Xc for all cooling rates applied. Synergistic crystallization behavior was clearly observed when TiO2 was added to PLA/talc for all TiO2 concentrations. Minimum t1/2 of 18 s was observed together with the increased Xc by around 26% when TiO2 was added to PLA/talc at 3 wt%. This reduced the injection cycle time from around 28 min, in neat PLA, down to 68 s at this TiO2 content. With the presence of talc and TiO2, the flexural modulus of the composites was improved significantly.

Ba-, Si- and vacancy-rich phlogopites from the talc-bearing sulfide ore deposit of La Creuse, Beaujolais, France

ABSTRACTBa-rich and Si-rich phlogopites occur in the talc-bearing rocks of the La Creuse sulfide ore deposit in Beaujolais, France. They form a group of compositions completely separated from the common Al-rich phlogopites that occur in the surrounding talc-free metasiltites and metarhyolites, with higher Ba and Mg and lower Al contents. The Ba-rich phlogopites have a relatively narrow compositional range (0.24 to 0.80 Ba per formula unit, for 44 valencies) with high and constant Si (5.8 atoms per formula unit, apfu) and Mg + Fe (5.6 apfu), probably buffered by the presence of talc. Compared to low-Al phlogopites from talc-free rocks, the excess charge introduced by the BaK–1 substitution is compensated by interlayer vacancies. Such a high level of interlayer vacancy (0.56 pfu), related to the talc-producing metasomatic conditions, is essential for the stability of this special group of Ba-rich and Si-rich phlogopites.Single crystal X-ray diffraction analyses were performed. Ba-rich and Si-rich phlogopite is monoclinic, space group C2/m, (R = 5.31%) with a = 5.3185(5), b = 9.2136(9), c = 10.1349(11) Å and β = 100.131(11)°. The occupancies of Mg/Fe and K/Ba were refined exploring different vacancies. The solutions giving the best R factor (4.77%) and goodness-of-fit (1.06) are obtained with 15% &lt; vacancy &lt; 40% at the interlayer site.

(Bio)degradable polymeric materials for a sustainable future – part 1. Organic recycling of PLA/PBAT blends in the form of prototype packages with long shelf-life

Prediction studies of advanced (bio)degradable polymeric materials are crucial when their potential applications as compostable products with long shelf-life is considered for today’s market. The aim of this study was to determine the effect of the polylactide (PLA) content in the blends of PLA and poly(butylene adipate-co-terephthalate) (PBAT); specifically how the material’s thickness corresponded to changes that occurred in products during the degradation process. Additionally, the influence of talc on the degradation profile of all samples in all environments was investigated. It was found that, differences in the degradation rate of materials tested with a similar content of the PLA component could be caused by differences in their thickness, the presence of commercial additives used during processing or a combination of both. The obtained results indicated that the presence of talc may interfere with materials behavior towards water and consequently alter their degradation profile.

Behavior of talc and mica in copper ore flotation

Abstract Talc and mica are major gangue minerals in many base metal ores including sulfide ores. Talc is a naturally hydrophobic mineral, and therefore it is easily floatable. There have been many studies to overcome this problem, and depress talc with various reagents. In this study the flotation of a copper ore in the presence of talc and muscovite was studied. It was found that talc can affect copper flotation mainly via froth phase. The copper grade and recovery were affected in the presence of only 7% talc. On the other hand, muscovite influenced the pulp phase via affecting the pulp rheology. The copper flotation grade was reduced in the presence of high amount (30%) of muscovite due to the entrainment, but its effect on the copper recovery was negligible.

An Experimental Study of the Formation of Talc through CaMg(CO3)2–SiO2–H2O Interaction at 100–200°C and Vapor-Saturation Pressures

The metamorphic interaction between carbonate and silica-rich fluid is common in geological environments. The formation of talc from dolomite and silica-rich fluid occurs at low temperatures in the metamorphism of the CaO–MgO–SiO2–CO2–H2O system and plays important roles in the formation of economically viable talc deposits, the modification of dolomite reservoirs, and other geological processes. However, disagreement remains over the conditions of talc formation at low temperatures. In this study, in situ Raman spectroscopy, quenched scanning electron microscopy, micro-X-ray diffraction, and thermodynamic calculations were used to explore the interplay between dolomite and silica-rich fluids at relatively low temperatures in fused silica tubes. Results showed that talc formed at ≤200°C and low CO2partial pressures (PCO2). The reaction rate increased with increasing temperature and decreased with increasingPCO2. The major contributions of this study are as follows:(1)we confirmed the formation mechanism of Mg-carbonate-hosted talc deposits and proved that talc can form at ≤200°C;(2)the presence of talc in carbonate reservoirs can indicate the activity of silica-rich hydrothermal fluids; and (3) the reactivity and solubility of silica require further consideration, when a fused silica tube is used as the reactor in highP–Texperiments.