Talc Particle Size Research Articles

Influence of talc particle size on the optical transparency, flame retardancy, and smoke release suppression of waterborne transparent fireproof coatings applied on wood surface

AbstractTalc with particle sizes of 1250 mesh (Talc‐1250), 3000 mesh (Talc‐3000), and 5000 mesh (Talc‐5000), used as synergist, was added into transparent fireproof coatings applied in wood substrates, and the influence of talc particle size on the comprehensive properties of the coatings was analyzed carefully. The results show that adding talc exerts super synergistic effect on enhancing the flame retardancy and smoke release suppression properties in the resulting coatings, and the synergistic efficiency of talc is varied with the talc particle size. Fire resistance analysis shows that the MTPPE2 coating containing Talc‐3000 exhibits better synergistic effects, accompanying a minimum back temperature of 106.3°C at 900°C and a maximum intumescent factor of 116.3. SEM‐EDS and FTIR analyses show that adding Talc‐3000 in the MTPPE2 coating contributes to the formation of a more intumescent and compact char against fire concomitant with the highest P/C mass ratio of 0.36 in char. Transparency analysis shows that the transparency of the coatings gradually decreases with the decrease of talc particle size, and the Talc‐1250 with exfoliated morphology imparts less loss of transparency to the coating while the Talc‐3000 and Talc‐5000 with intercalated morphologies induce more obvious light scattering in the coatings.Highlights Talc was used to enhance the comprehensive properties of transparent fireproof coatings. Synergistic efficiency of talc on the fire safety of coatings varies with its particle size. Talc with a particle size of 3000 mesh exerts an optimum synergism in the coatings. Transparency of the coatings gradually decreases as talc particle size decreases.

Application of factorial model for an optimization of partial replacement of feldspar by talc on the sintering process

AbstractThis research used a factorial model containing two levels and three variables to evaluate the partial substitution of sodium feldspar (albite) by a talc ore found in abundance in the region of Itaiacoca—Brazil. The model can also be used to verify the influence of initial talc particle size, proportion, and sintering threshold temperature on the following physical properties, such as linear shrinkage, water absorption, bulk density, total porosity, and firing color. In this study, the mechanical strength of the compositions was evaluated by the flexural strength test. The factorial model indicated the sintering temperature as the variable that most affects the samples’ densification and the proportion of talc as the variable that changes the firing color. The experiment that used a higher sintering temperature combined with a coarser talc granulometry presented the highest mechanical strength. When more refined granulometry was used, there was the beginning of an overfire process. Water absorption values in the range of .04% and modulus of rupture of 49 MPa were obtained, confirming the talc's effectiveness as a secondary flux agent suitable for the formulation of ceramic bodies.

Effect of Talc Particle Size in Detergents for Fruits and Vegetables on the Ability to Remove Pesticide Residues.

Detergents containing abrasive talc particles for washing fruits and vegetables were designed and investigated. Detergent prototypes were developed with the following composition: 40% talc particles, 1.5% surfactants, 5% ethyl alcohol, 1% sodium citrate, 1% sodium carbonate, 1.5% glycerin, and 0.5% preservative. Xanthan gum (0.5% concentration) was used as a viscosity modifier to stabilize the dispersion of talc particles. Three types of detergent prototypes were prepared, differing in the size of the talc particles. The following fractions were used: 50–125, 250–500, and 710–1000 μm. The particle size effect on the effectiveness of the removal of surface pesticide residues was investigated. A specially developed methodology was used. Three types of pesticides (boscalid, acetamiprid, and pyraclostrobin) were applied to a cherry tomato, tangerine, and cucumber, and then a model washing process was performed using the developed detergents. The changes in the pesticide content on the surface of fruit and vegetables were assessed by liquid chromatography–tandem mass spectrometry. Detergents with talc particles of sizes 50–125 and 250–500 μm were more efficient in the removal of pesticide residues from the surface of fruit and vegetables compared to detergents with 710–1000 μm talc particles.

Structural, Mechanical and Flammability Characterization of Crosslinked Talc Composites with Different Particle Sizes

The influence of filler particle size on selected physicochemical and functional properties of polymer composites was analyzed. The following test was carried out for the system: the bisphenol A glycerolate (1 glycerol/phenol) di-methacrylate (BPA.DM) was subjected to UV-polymerization in bulk with N-vinyl-2-pyrrolidone (NVP) as a polymer matrix and talc with particle sizes ranging from ≤8 to 710 µm as a non-toxic and cheap mineral filler. An effective method of preparing cross-linked polymeric composites with talc was developed. The obtained samples were subjected to structural analysis and the thermal, mechanical and flammability properties were assessed. It has been empirically confirmed that the talc particles are incorporated into the composite structure. However, with increasing particle size, the composite heterogeneity increases. In the case of the developed method of sample production, homogeneous systems were obtained for particles in the ≤8–250 µm range. The surface roughness of the samples correlates directly with the size of talc particles. The value of Young’s modulus during the axial stretching of samples decreases with the increasing size of talc particles. For the composites containing ≤15 and ≤35 µm talc particles, the highest values were obtained under bending conditions. There was no equivocal effect of particle size on the composites’ swelling in water. The addition of talc reduces the flame height and intensity slightly. The biggest difference was obtained for the composites containing relatively large talc particles. It was proved that the selected properties of polymer composites can be controlled depending on the size of the talc particles.

Experimental Study on Factors Influencing Throughput Rate and Process of Polymer-Mineral Filler Mixing in a Twin Screw Extruder

Abstract The experimental study of mixing polymer (polypropylene, PP) with mineral filler (Talc) by both simultaneous and separate feed system in a twin screw extruder was described. In this study, melt flow rate (MFR) of PP, talc particle size and talc mixing ratio to PP were selected as parameters of interest. It was found that these parameters had influences on the maximum throughput rate of mixture. In the cases of constant talc particle size and mixing ratio while MFR of PP was varied from 1.8 to 33, it was observed that throughput rates of all mixtures with different MFR values increased as a function of screw speeds. Throughput rates of the mixture of lower MFR PP (MFR = 1.8) were slightly lower than those of the higher MFR mixture (MFR = 10, 33) for both simultaneous and separate feed systems. With regard to effects of talc particle size, compounds having fixed talc mixing ratio showed lower throughput rates when talc particle size was smaller. In the case where talc mixing ratio was varied, compounds with fixed MFR of PP and talc particle size showed lower throughput rates when talc mixing ratio was larger. The mixing state in the mixing zone was also observed. Based on the overall findings, the mechanisms of filler mixing were clearly understood. The observed mixing patterns were similar for both simultaneous and separate feed systems. It was found that the elimination of the air accompanying the filler when the filled polymer mixture passed down the extruder is important for mixing. Through the experimental observations, the schematic diagram, the model and the flow chart of the proper filler mixing process were proposed.

The Effect of Pore Structure on Thermal Characteristics of a Cordierite Diesel Particulate Filter for Heavy Duty Diesel Vehicle

As emissions regulations are tightened, various engine and emission reduction improvements have been applied. The reduction of particulate matter (PM), a major diesel engine emission, relies solely on after-treatment in the diesel particulate filter (DPF). It is not possible to satisfy current exhaust regulations without a DPF installed downstream of a diesel engine. Therefore, in the design of DPF systems, thermal stability and durability at the high temperatures experienced during the regeneration process are considered critical in determining the substrate material, as any defects (cracking, damage, or melting) cause increased pollutant emissions. In this study, the regeneration characteristics of 10.5 in cordierite DPF substrates applied in large commercial vehicles were investigated according to pore structure. The pore structure was changed while maintaining the thermal expansion coefficient and thermal properties by changing the particle size of talc during fabrication. Two different substrate compositions were evaluated and applied in a 6-L diesel engine to analyze their thermal characteristics during normal and uncontrolled (drop-to-idle) regeneration according to PM loading. The improvement in pore structure was observed to increase the PM oxidation rate under normal regeneration and extended the PM loading limit under uncontrolled regeneration.

Analytic comparison of talc in commercially available baby powder and in pelvic tissues resected from ovarian carcinoma patients

ObjectiveMeasure the size and shape of talc particles in talcum powder and compare this data to the size and shape of talc particles found in surgically resected tissues from patients with ovarian carcinoma. MethodsUsing polarized light microscopy (PLM) and scanning electron microscopy (SEM), we measured the size and shape of talc particles in samples of talc-containing baby powder (TCBP) and surgically resected pelvic tissues (hysterectomies) from talc-exposed patients with ovarian carcinoma. ResultsThe most frequent class of particles in TCBP can be unequivocally identified as talc, using both polarized light microscopy and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX). The talc particles found in resected tissues from ovarian carcinoma patients are similar in size and shape to the most abundant morphological class of particles in TCBP. ConclusionsThis finding, combined with previous epidemiological literature and tissue-based analytical studies, provides further evidence that the small, isodiametric particles that dominate TCBP can migrate from the perineum and become lodged in distal structures in the female reproductive tract, where they may lead to an increased risk of developing ovarian carcinoma.

Effects of Ball Size on the Grinding Behavior of Talc Using a High-Energy Ball Mill

The properties and preparation of talc have long been investigated due to its diverse industrial applications, which have expanded recently. However, its comminution behavior is not yet fully understood. Therefore, having better control of the particle size and properties of talc during manufacturing is required. In this study, we investigate the effect of the ball size in a high-energy ball mill on the comminution rate and particle size reduction. High-energy ball milling at 2000 rpm produces ultrafine talc particles with a surface area of 419.1 m2/g and an estimated spherical diameter of 5.1 nm. Increasing the ball size from 0.1 mm to 2 mm increases the comminution rate and produces smaller talc particles. The delamination of (00l) layers is the main comminution behavior when using 1 mm and 2 mm balls, but both the delamination and rupture of (00l) layers occurs when using 0.1 mm balls. The aggregation behavior of ground talc is also affected by the ball size. Larger aggregations form in aqueous solution when ground with 0.1 mm balls than with 1 mm or 2 mm balls, which highlights the different hydro-phobicities of ground talc. The results indicate that optimizing the ball size facilitates the formation of talc particles of a suitable size, crystallinity, and aggregation properties.

Effect of Talc Size on Surface Roughness and Glossiness of Polypropylene Injection Molding Application to Automotive Plastics

Talc‐containing polypropylene (PP) resin is extensively employed in automobiles. Herein, considering the microstructure transfer process in injection molding, the effect of the talc's dispersibility and particle size on this process and its impact on the gloss level of the product were investigated. Results show that a fine unevenness of about several micrometers was self‐formed by the shrinkage of PP in nontransferred areas due to the blending of talc. Additionally, the amount of self‐formed unevenness tended with an increase in the average particle size of talc. Furthermore, due to PP shrinkage and different densities of talc, it was observed that a fine tiger‐stripe pattern was self‐formed using special molds with modified microstructure. This self‐formed fine unevenness changes the gloss level owing to the diffused light reflection effect. This study proposes controlling this change by controlling the average particle size of talc and structure of the mold. POLYM. ENG. SCI., 60:132–139, 2020. © 2019 Society of Plastics Engineers

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.

Developing properties in porous tapes from die-drawing of polypropylene composites

ABSTRACTThe objective of this research was to investigate process limits and properties of porous tapes obtained by solid-phase die-drawing of talc-filled polypropylene to a thickness of 1 mm, which is low for this process. Two different composites with different talc particle size distributions were drawn under similar conditions and the development of porosity with increasing linear draw ratio was more gradual in the drawn product with smaller mean particle size, leading to greater mechanical strength even at a final porosity level matching that in the other drawn material. The morphology of the drawn products was examined to explain these trends.

Particle Size Analysis of Nano-sized Talc Prepared by Mechanical Milling Using High-energy Ball Mill

Talc, hydrous magnesium phyllosilicate, is one of the most popular industrial minerals due to their chemical stability and adsorptivity. While micro-sized talc has long been used as a filler and coating, nano-sized talc recently is attracting attention as additives for improving the stability of nanocomposites. In this study, we produced the nano-sized talc powder by mechanical method using high energy ball mill and investigated the changes in particle size and crystallinity with increasing milling time up to 720 minutes. X-ray diffraction results show that the peak width of talc gradually as the milling proceeded, and after 720 minutes of pulverization, the talc showed an amorphous-like X-ray diffraction pattern. Lase diffraction particle size analysis presents that particle size of talc which was ~12 μm decreased to ~0.45 μm as the milling progressed, but no significant reduction of particle size was observed even after grinding for 120 minutes or more. BET specific surface area, however, steadily increases up to the milling time of 720 minutes, indicating that the particle size and morphology change steadily as the milling progressed. Scanning electron microscope and transmission electron microscope images shows that layered particles of about 100 to 300 nm was aggregated as micro-sized particles after pulverization for 720 minutes. As the grinding time increases, the particle size and morphology of talc continuously change, but the nano-sized talc particles form micro sized agglomerates. These results suggest that there is a critical size along the a, b axes in which the size of plates is reduced even though the grinding proceeds, and the reduction of plate thickness along the c axis leads the increase in specific surface area with further grinding. This study could enhance the understanding of the mechanism of the formation of nano-sized talc by mechanical grinding.

Description of Particle Size, Distribution, and Behavior of Talc Preparations Commercially Available Within the United States.

Widespread use of talc pleurodesis remains controversial for many providers concerned by adverse events such as respiratory failure, which are sometimes fatal. Particle talc size has been implicated in these adverse effects, mainly on the basis of animal studies utilizing large amounts of talc or in observational studies performed on different continents with different talc preparations and doses. Our aim was to determine the particle size and distribution of only the commercially available US-talc preparations and whether the fluid content can affect this distribution. Commercially available US talc was evaluated under scanning electron microscopy and dynamic light scattering (DLS). Distribution of talc particle size was obtained in saline and various protein-based solutions. Talc particle size by DLS was performed with commercially available Sterile Talc Powder and Sclerosol Intrapleural Aerosol. Sterile Talc Powder demonstrated a median diameter of 26.57 μm with a range of particle sizes from 0.399 μm to 100.237 μm. Sclerosol demonstrated a median diameter of 24.49 μm with a range of particle sizes from 0.224 μm to 100.237 μm. The exposure of talc to a protein rich environment (bovine serum albumin and human pleural fluid) led to the development of measureable, new, larger aggregated particle (>100 μm). Currently available US talc seems to have size characteristics similar to previous described "graded" talc preparations. The exposure of talc to a protein rich environment seems to modify the overall distribution of talc particle size when examined by DLS.

Talc as Reinforcing Filler in Polypropylene Compounds: Effect on Morphology and Mechanical Properties

Talc represents one of the most useful mineral fillers which are compatible with the polypropylene (PP). It is characterized with its lamellar structure. The introduction of 30% by weight of talc, three types differing with the particle size d50 and the composition, has not only a positive influence on stiffness and crystallinity but also it decreases the impact strength and tenacity. The abrasive wear behavior depends mainly on the particle size of talc. Microscopic observations revealed that the talc layers are aligned along the injection flow direction, and uniformly dispersed in the PP matrix.

Structure and properties of highly filled poly (vinyl alcohol)/talc composites prepared through thermal processing: effects of talc size

Poly (vinyl alcohol) (PVA), a multi-hydroxyl polymer with excellent comprehensive properties, is an expected candidate to prepare high-performance polymer-based composites without using any coupling agents or compatibilisers. However, the poor thermal processability of PVA is its biggest obstacle. In this paper, by adopting polyol as a plasticiser, highly filled PVA/talc composites with good mechanical properties were successfully obtained through melt extrusion and injection, and the effects of talc size on structure and properties of the composites were studied. The results showed that talc highly filled PVA composites had satisfying melt processability, and the decrease of talc particle size increased the –OH groups on the edges of the talc layers, thus improving the compatibility between talc and PVA, and making talc particles dispersed more uniformly in PVA matrix. As a result, the composites with smaller talc particles had the higher threshold filler concentration to form the filler networks and the better flow behaviour. The smaller talc flakes also exhibited higher orientation in PVA matrix and induced more PVA molecular chains to orient along the melt flow direction, leading to the enhancement of the mechanical properties of the composites.

Fat crystallization with talc particles is influenced by particle size, concentration, and cooling rate

We recently found that new types of additives including talc promoted the crystallization of monoacid saturated triacylglycerols (TAGs) in stable polymorphs. This study reports the effects of size and concentration of talc particles and cooling rate on the crystallization of trilauroylglycerol (LLL), tripalmitoylglycerol (PPP), and 1,3‐dipalmitoyl‐2‐oleoyl glycerol (POP). Talc particles were mixed with molten TAGs, and the mixtures were then cooled at designated cooling rates. Polymorphic crystallization was observed by simultaneous use of X‐ray diffractometry and differential scanning calorimetry and by polarized optical microscopy. The following results were obtained: (i) talc promoted the crystallization of LLL in stable polymorphs with decreasing particle size and increasing concentration; (ii) the promotional effects were influenced by the cooling rate; (iii) the same behavior was observed for PPP and POP; and (iv) hydrophobic modification of talc surfaces did not affect the promotional effects. These results indicate that talc particles having median sizes of less than 2.5 μm and concentrations exceeding 0.1 wt.% effectively promote fat crystallization, and that the promotional effects can be maximized by choosing proper cooling rates according to the target fats. Furthermore, we propose a model of the heterogeneous nucleation of TAG crystals taking account of the molecular adsorption on cleavage surfaces of talc.Practical applicationsTalc is widely approved as a food‐grade ingredient, and the additive effects on various triacylglycerols widen its applicability to fat‐based food and cosmetic materials.With grinding, talc particles exhibit anisotropic surfaces: cleavage surfaces are hydrophobic, and edge (lateral) surfaces are hydrophilic. Hydrophobic modification of the edge surfaces does not affect the additive effects of talc particles on fat crystallization, indicating adsorption of fat molecules on the cleavage surfaces.

Thermal and mechanical analysis of injection moulded poly(lactic acid) filled with poly(ethylene glycol) and talc

In our research, the effect of talc particle size was analysed on the thermal and mechanical properties of renewable resource-based, biodegradable polymer poly(lactic acid) (PLA). Various talc particles with an average particle size of 24, 1.9, and 0.7 μm were blend mixed with PLA in 10 and 20 mass% containing no or an additional 10 mass% of poly(ethylene glycol) (PEG) to increase molecular chain mobility. It was demonstrated that with decreasing talc particle size, its nucleation ability increased as well as all of the investigated mechanical properties of the compounds, however, in case of compounds containing PEG, this tendency was the opposite according to Charpy impact strength results. The talc with the best nucleating ability was selected and a full factorial design of experiment was made to optimise the talc and PEG content and to investigate their cross-effect in the 1-3-5-10-15 mass% additive content range. Finally, the effect of mould temperature and cooling time was analysed on the crystallinity and heat deflection temperature of the final injection-moulded parts.

Role of particle size and preflocculation of talc in improvement of paper properties

Mineral fillers are added during papermaking to improve the optical and printing properties of paper and decrease energy costs. Filler loading using conventional approaches has some disadvantages, such as reduction in paper strength. The finer filler, the more the strength loss. Several methods and materials have been reported to overcome or alleviate the same, but with higher costs. Our approach provides an economically viable solution to the problem, using conventional papermaking materials. Talc filler of different particle sizes, preflocculated using different doses of cooked amphoteric starch, were used for papermaking. Relatively higher filler retention, paper strength, and hydrophobicity of paper were obtained with preflocculated talc compared to native talc. The optical properties of paper were unchanged on the loading of similar talc after preflocculation. The preflocculated talc of finer particle size provided higher opacity at similar ash, as well as paper strength, than the native talc of coarser size.

Influence of talc particle size and content on crystallization behavior, mechanical properties and morphology of poly(lactic acid)

This research aimed to employ inorganic filler such as talc to promote crystallization in poly(lactic acid) (PLA). Three different talc particle sizes, namely 1, 5 and 30 µm, were used as nucleating agents; each was compounded with PLA at various contents from 0 to 10 wt%. The crystallization temperature (T c) reduced most rapidly from 128 to 107 °C with the presence of 1 wt% talc. Beyond this concentration, the T c still decreased but only minutely. Compared to other sizes, finer talc particles were found to promote a slightly higher degree of crystallinity. X-ray diffraction peaks indicated that the α-crystal was formed in all PLA/talc compositions. The heat distortion temperature values suggested that the modified PLA could resist the thermal deformation from 58 °C to a maximum value of 139 °C when 1 µm talc was added at 10 wt%. With the presence of talc, the composites were more brittle and both tensile elongation at break and impact strength were decreased.

Mechanical activation as sintering pre-treatment of talc for steatite ceramics

The effect of vibratory mill induced mechanical activation on the change of the particle size, crystallinity and the phase transformations of the minerals present in the activated material, was studied with the purpose of decreasing of the sintering temperature of talc (Mg3Si4O10(OH)2) as raw material which is the basic component of the steatite ceramics. The aims of the conducted investigation were, also, increasing of the reactivity of the comminuted raw material and establishing of the optimal activation period. The properties of the activated talc induced by mechanical force were expressed in form of the grain inertia change which was measured by means of automatic grain counter. Mechanically activated grains are the most convenient mineral form for physical concentration since the energy change of the mill-material system is recorded on them. The effect of dry grinding on the structure, particle size and shape of talc was studied by means of XRD, DTA and SEM/EDS methods. Activation of talc produced an increase of the starting surface area value progressively from 4.5 m2/g up to a maximum of 108.5 m2/g achieved at 30 min. A subsequent decrease of rate of surface area change and the rate of size reduction were observed following the prolonged grinding. Talc activated in vibratory mill for optimal 30 min showed properties which positively influence the decrease of sintering temperature and the increase of the sintering rate of steatite ceramics.