Addition Of Talc Research Articles

Effect of talc addition on pyroplastic deformation of an alumina strengthened porcelain

Effect of talc addition on pyroplastic deformation of an alumina strengthened porcelain

Adding talc particles improves physical properties of palm oil‐based shortening

This paper reports the effects of adding talc particles on the physical properties of palm oil (PO)‐based shortening formed by working refined PO (RPO) after rapid cooling. We examined the thermal and viscoelastic behavior of RPO in bulk fat systems, and the polymorphism and hardness of the shortening in the presence and absence of talc particles. In addition, the microstructure of fat crystals formed was observed. The effects of talc addition are summarized as follows: (i) When RPO was cooled at a rate of 5°C/min, crystallization of the high‐melting fraction, including tripalmitoylglycerol (PPP) and 1,3‐dipalmitoyl‐2‐oleoyl glycerol (POP), was preferentially promoted to form small‐sized microcrystals. During cooling, the increase in the viscoelasticity of RPO was suppressed at low temperatures. (ii) When the shortening was stored at 5°C, β′‐crystallization of 1‐palmitoyl‐2,3‐dioleoyl glycerol (POO) and β‐crystallization, probably of a molecular compound (MC) of POP and 1,2‐dipalmitoyl‐3‐oleoyl glycerol (PPO), were delayed compared to β′‐crystallization of PPP and POP. During storage, the homogeneity of the fat crystal dispersion improved and the hardness of the shortening decreased. These results indicate that talc improved the physical properties of the PO‐based shortening by changing the crystallization kinetics and the networking processes of the fat crystals.Practical applications: The present study showed that adding talc particles effectively improved the physical properties of palm oil (PO)‐based shortening during storage. This is considered beneficial for resolving problems in the quality control of PO‐based products, such as post‐hardening and the formation of granular crystals due to low rates of crystallization.Storage modulus (G′) of refined palm oil (RPO) with and without talc particles in bulk fat systems, obtained from dynamic viscoelasticity measurements during cooling at a rate of 5°C/min. Adding talc particles drastically changed the three‐stage increases in G′ of pure RPO, promoting the first‐stage increase but suppressing subsequent increases at low temperatures.

Morphology and Properties of Polypropylene Foaming Sheet with Alternating Multilayered Structure

In this work, the foaming sheet was designed as alternating multilayered foam/film structure of foaming layers and film layers. The foaming layer contained polypropylene (PP)/high density polyethylene (HDPE)/Talc ternary composites. The film layer contained PP only. The rheological data showed that the melt elasticity of PP was obviously improved by the addition of HDPE and talc. The results exhibited that the alternating multilayered structure was well kept and hardly influenced by the foaming layers, and then the mechanical properties were obviously improved. The cell in the alternating multilayered sheet with 16 layers was smaller and more homogenous than that in pure PP foaming sheet.

Sodium chloride compared to talc as processing aid has similar impact on volatile compounds but more favorable on ortho‐diphenols in virgin olive oil

The possibility of improvement of olive paste extractability by addition of talc or NaCl (1, 2, and 3% mass ratio in olive paste), or their combinations (“talc 1.5% + NaCl 1.5%”; “talc 1% + NaCl 2%”; “talc 2% + NaCl 1%”), was investigated on a laboratory scale. Volatiles in oil samples were determined by headspace solid‐phase micro‐extraction with GC‐MS, while ortho‐diphenols were assessed by solid phase extraction and UV‐VIS spectrophotometer. Significantly higher extractability of oil (from 25 to 29% compared to control, p < 0.05) was obtained by 3% of talc or NaCl and their combinations in mass ratio 1:2 or 2:1. At 3% addition level, no significant decrease of C6 aldehydes was observed, while significant increase of C6 alcohols (talc or salt) as well as of C5 compounds and terpenes (salt) occurred. Mass ratio of ortho‐diphenols in oil was not influenced by talc, while NaCl led to significantly higher values compared to control (by 10–15%, p < 0.05).Practical applications: The influence of processing aids on characteristics of virgin olive oil has mainly been evaluated through the standard chemical quality parameters, while limited information about desirable volatile compounds of thus obtained extra virgin olive oils has been published so far. The results of this research show that NaCl can be used not only as a tool for enhancing the extractability, but also as a means for improving the nutritional value of virgin olive oils from cultivars which generally show low levels of hydrophilic phenols.The efficiency of talc and NaCl (processing aids acting on the basis of physical principles) in improvement of so‐called difficult olive paste extractability is similar, but the advantages of NaCl are less pronounced changes of compounds responsible for fruity aroma, as well as increase of ortho‐diphenols, compounds known for their antioxidant activity and health‐promoting properties.

First and second centrifugation of olive paste: Influence of talc addition on yield, chemical composition and volatile compounds of the oils

Second centrifugation of olive paste is often carried out to recover the residual oil of the olive paste, leading to a product that must be marketed as raw olive pomace oil. An experimental investigation was carried out to assess yield, chemical composition, and volatile compounds of oils obtained after the first and the second centrifugation of olive paste. Olives from Coratina cultivar were used in trials and were processed by adding 1 g/100 g and 2 g/100 g of technological coadjuvant micronized talc, as well as without talc addition, as control. The obtained results evidenced that the second centrifugation determined a significant decrease of residual oil in pomace. The addition of talc determined a significant increase of oil yield respect to control without talc, but only after the first centrifugation. A scarce increase of oil yield was observed after the second centrifugation, in presence of talc, that would render economically not viable the use of a second working line. Moreover, the oil obtained after the second centrifugation showed higher extent of oxidative and hydrolytic degradation than the oil from the first centrifugation. Some volatile compounds, derived from oxidative and fermentative phenomena, were observed in specific amounts in the oil of second centrifugation.

High resolution melting analysis of DNA microsatellites in olive pastes and virgin olive oils obtained by talc addition

Talc (hydrated magnesium silicate) is a physical coadjuvant that can be employed in the production of extra virgin olive oil to increase yield. The adsorbent properties of talc could hamper DNA recovery, leading to false negatives in DNA analysis. The aim of this work was to verify the effect of talc addition on olive oil DNA by targeting four selected microsatellites. Olive processing trials were carried out at two different levels of talc (1 and 2%) and without talc (control). DNA extraction yield and purity level were ascertained, and High Resolution Melting (HRM) analysis of microsatellites was subsequently applied to the extracted DNA. Neither the DNA extraction yield nor the A260/230 and A260/280 ratios showed significant differences between control and talc‐treated samples. Higher values of A260/230 and lower yields were observed in olive oils than in olive pastes. The DNA microsatellites analyzed showed identical HRM profiles in all the samples, excluding any effect of talc and confirming the genetic homogeneity of the olive lot processed (cv. Coratina).Practical applications: High added‐value mono‐cultivar extra virgin olive oils are niche products very appreciated by consumers. DNA analysis is able to reveal mixing with cultivars different from those declared in the label. The use of talc in olive oil industries has progressively increased to improve yield. The results obtained prove that the DNA‐based methods set up until now to check the authenticity of extra virgin olive oil can be effectively carried out also in oils produced by using talc. In addition, the results are among the first applications of HRM to the food sector and evidence the feasibility of this technique along the olive oil chain for checking both olive pastes and oils.Talc (hydrated magnesium silicate) is a physical coadjuvant that can be employed in the production of extra virgin olive oil to increase yield. The adsorbent properties of talc could hamper DNA recovery, leading to false negatives in DNA analysis. By means of High Resolution Melting (HRM) analysis, DNA samples from talc‐treated olive pastes and oils were compared with untreated control based on the shape of temperature‐shifted melting curves. For the same microsatellite, the different samples analyzed showed almost identical HRM profiles. This result excluded any effect of talc addition during olive processing in the analysis of DNA microsatellites of olive oil.

Modulation of bitterness and pungency in virgin olive oil from unripe “Picual” fruits

Singular virgin olive oils (VOOs) come from unripe olives that show different characteristics affecting processing and oil sensory properties. This work is aimed to study the effect of olive paste malaxation conditions on phenolic fraction and intensities of bitter and pungent sensations in VOOs from unripe “Picual” olives. Experiments were carried out using “Picual” fruits harvested at early dates for three consecutive crop seasons. The malaxation conditions assayed using a factorial design were: time (60 and 90 min), temperature (18, 30, and 40°C) and micronized talc addition (0 and 1%). The main factors affecting oil phenol content were the crop year, malaxation temperatures, and micronized talc addition whereas for malaxation time the effect was not significant. The high olive fruit moistures had a great importance in the oil phenol content and the related sensory parameters. Results indicated as for higher temperature the phenol content and bitterness K225 increased although its effect varied by crop year. Micronized natural talc addition increased the total phenol content and the K225 values. When intensities of pungency and bitterness of the oils were ranked by sensory analysis those obtained at lower temperature were classified as less bitter and pungent. Therefore for early harvesting dates the kneading conditions can be regulated to obtain VOOs with different sensory characteristics and phenol content.Practical applications: Effect of paste malaxation conditions on the virgin olive oil (VOO) bitterness, pungency, and phenolics has been studied for early harvested “Picual” fruit. Bitterness and pungency in “Picual” VOO could be modulated by regulating the malaxation temperature achieving the lower intensities at 18°C without micronized talc addition.Temperature was the olive paste malaxation variable with the highest effect on phenol content in virgin olive oil from early harvested “Picual” fruits. Lower temperature reduced oil phenol content and then, its bitterness and pungent intensities.

The investigation of selected properties of the porous moulded parts from talc-filled PP composites

The investigation of the influence of chemical blowing agent addition and talc filler on structure and selected properties (weight, thickness, mechanical properties, surface state – gloss and colour – and thermal conductivity) of moulded parts from PP was the aim of this work. Microscopic investigations were made using mould with cavities of variable height. Addition of blowing agents to polymer material permits reducing of the injection cycle to the injection phase and cooling. Investigations showed that talc addition permits to obtain fine-cellular structure in moulded parts with blowing agent. It is possible, because talc can act as a nucleating agent, which has been shown in literature. As a result, moulded parts with blowing agent and talc had low weight, good mechanical properties compared to solid, unfilled parts. Main disadvantage of using blowing agent and talc is worsening of gloss and colour changing.

Synergistic effects of nucleating agents and plasticizers on the crystallization behavior of poly(lactic acid).

The synergistic effect of nucleating agents and plasticizers on the thermal and mechanical performance of PLA nanocomposites was investigated with the objective of increasing the crystallinity and balancing the stiffness and toughness of PLA mechanical properties. Calcium carbonate, halloysite nanotubes, talc and LAK (sulfates) were compared with each other as heterogeneous nucleating agents. Both the DSC isothermal and non-isothermal studies indicated that talc and LAK were the more effective nucleating agents among the selected fillers. Poly(d-lactic acid) (PDLA) acted also as a nucleating agent due to the formation of the PLA stereocomplex. The half crystallization time was reduced by the addition of talc to about 2 min from 37.5 min of pure PLA by the isothermal crystallization study. The dynamic mechanical thermal study (DMTA) indicated that nanofillers acted as both reinforcement fillers and nucleating agents in relation to the higher storage modulus. The plasticized PLA studied by DMTA indicated a decreasing glass transition temperature with the increasing of the PEG content. The addition of nanofiller increased the Young’s modulus. PEG had the plasticization effect of increasing the break deformation, while sharply decreasing the stiffness and strength of PLA. The synergistic effect of nanofillers and plasticizer achieved the balance between stiffness and toughness with well-controlled crystallization.

Talc Nanoparticles Influence on Thermoplastic Corn Starch Film Properties

Composite films of TPS with talc nanoparticles were obtained by thermo-compression in order to study the effect of this filler on structure, optical, and thermal properties. TPS-talc films showed good appearance and homogeneous thickness. Talc addition increased the amount of rigid phase in nanocomposite films, thus their cross-sections resulted more irregular than those of TPS ones. Talc preferential orientation within matrix and good compatibility between particles and TPS were evidenced. TEM observation showed scattered randomly dispersed individual talc platelets. Matrix crystallinity degree was not significantly affected by particles presence. Nanocomposite films were optically transparent due to the laminar morphology and nanosized particles. Materials microstructure presented glycerol- and starch-rich domains. Talc incorporation higher than 3% w/w increased softening resistance of nanocomposites as stated by DMA assays. TPS relaxation temperature of glycerol-rich phase was shifted to higher values since talc nanoparticles reduce starch chains mobility.

Evaluation of atmospheric CO2 sequestration by alkaline soils through simultaneous enhanced carbonation and biomass production

A series of microcosm experiments were conducted. The objectives were to evaluate the effects of Ca/Mg-bearing materials on CO2 sequestration in highly alkaline sodic soils (Sodosol) through carbonation and biomass production. Application of gypsum resulted in an increase in inorganic carbon and a decrease in organic carbon. The addition of talc did not significantly enhance carbonate formation. Soluble CaCl2 and MgCl2 did not have significantly better effects on soil carbonation, as compared to gypsum. The one-year growth experiment using five widely cultivated pasture grasses revealed that accumulation of carbonates following gypsum application could be inhibited by plant growth; the organic acids secreted from plant roots were likely to facilitate soil carbonate dissolution. In comparison with pedogenic carbonation, carbon sequestration by biomass production was much more evident. However, the biomass carbon gain varied markedly among the five species with Digitaria eriantha showing the highest biomass carbon gain. This further enhanced the accumulation of soil organic carbon. At the end of the experiment, an estimated CO2 sequestering capacity of 93t/ha was achieved. The research findings have implications for cost–benefit analysis of alkaline soil reclamation projects.

Food packaging bags based on thermoplastic corn starch reinforced with talc nanoparticles

Packaging bags from thermo-compressed films of thermoplastic corn starch containing talc nanoparticles (0, 1, 3 and 5% w/w) were developed. Mechanical properties of films were studied by two different techniques (tensile tests and quasi-static assays) revealing starch films reinforcement by talc addition. Strength improvement of thermoplastic starch films with talc concentration higher than 3% w/w was reflected in an increase in both Young's modulus and yield stress. Talc particles modified failure mode of thermo-seal of thermoplastic starch films giving another bags opening possibility. Usually, bags based on starch films could be only opened by tearing while those of starch-talc bionanocomposites could be torn or peeled off. Finally, in order to evaluate packaging bags tightness, films barrier properties were determined. Water vapor and oxygen permeability were reduced 54 and 26%, respectively, by talc addition (3% w/w) to thermoplastic starch.

Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

Use of talc for filamentous bulking control in effluent treatment plant

One of the main existing operational problems in activated sludge effluent treatment processes is the poor sedimentation of the biological sludge in the secondary clarifiers. This poor settleability of the sludge is, generally, associated with excessive growth of filamentous bacteria in the bioreactor causing sludge filamentous bulking. In Brazil, many pulp and paper mills have faced problems related to sludge filamentous bulking in their effluent treatment plants experiencing a significant reduction in COD and BOD removal efficiency and a loss of suspended solids in the treated effluent. The addition of talc to increase floc density for the control of filamentous bulking has been studied. The objective of this study was to test the use of talc for the control of filamentous bulking. The bio-sludge used was obtained from a recycling paper mill and had an abundance of filamentous bacteria Type 021N. The experiment consisted of five bioreactors operating batch wise with sludge age of ten days. Different talc applications were used: 0%, 25%, 50%, 75% and 100% in relation to the total suspended solids in the aeration tank. The following analyses were carried out to monitor the system: suspended solids, sludge volumetric index (SVI) and chemical oxygen demand. Successive additions of talc contributed for the reduction of IVL. Dosages of 75% and 100% showed to be most efficient to improve settleability of the sludge. The presence of talc did not interfere with biological activity of the sludge. However, it was observed an increase of the total suspended solid concentration in the aeration tank. The addition of talc had a temporary effect on sludge settleability, so it was necessary to add repeatedly talc in the reactor in order to maintain a low sludge volumetric index.

Elongational Flow-induced Crystallization in Polypropylene/Talc Nanocomposites

During the processing of the polymers, macromolecules undergo a significant flow just before or during cooling. For semi-crystalline materials, the flow widely influences both the crystallization kinetics and the resulting crystalline orientation. Moreover, in the presence of nucleating filler, even more with a high aspect ratio, these phenomena of crystallization under elongational conditions can be disrupted. In this study, melt blended nanocomposites of PP /Talc were processed using an internal mixer. An elongational rheometer was used to generate well controlled different extensional flow conditions. Samples were then characterized by WAXS to reveal and quantify the fillers and PP crystalline phase orientation. Crystalline orientation of polypropylene was found to be strongly affected by the addition of Talc under extensional flow and the Talc orientation.

Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid).

Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

Effect of talc addition on the extraction yield and quality of extra virgin olive oils from Coratina cultivar after production and during storage.

An experimental investigation was carried out with the aim to evaluate the effect of talc on the extraction yield and quality of extra virgin olive oils from Coratina olives after production and during storage. A significant effect of talc, added in the malaxer, on both yield and oil quality was observed. The addition of 1% talc lead to a 15% decrease of the residual oil in the olive-pomace, while higher amounts of talc did not determine further significant variations. The use of talc caused also a significant decrease of the peroxide value and tocopherols and a significant increase of carotenoids, chlorophylls, phenols, antioxidant activity and K270, while no influence was detected on free fatty acids and K232. Finally, during storage the differences among the oils were maintained as immediately after their production, with the exception of chlorophylls.

Effect of Addition of Talc on the Properties of Feldspar-Kaolinitic Clay Blends during Heating

Effects of low addition of talc (up to 8 wt%) on thermal transformations of feldspar-kaolinitic clay blends were investigated by X-ray diffraction, scanning electron microscope and Fourier-transform infrared spectroscopy. The variations of some properties (firing shrinkage, water absorption, density and bending strength) versus talc additions were measured. It was found that talc additions did not affect the presence of neoformed phases (mullite, spinel and glassy phase) but markedly influenced their contents. With up to 4 wt% talc addition, the amount of the formed phases increased with the increase of talc content; consequently shrinkage increased along with strength and density. Apparently, talc derivative oxide (MgO) facilitated the sintering process. For >4 wt% talc, the effect of alkali fluxes reduced because of the abundance of MgO, and consequently the glassy phase content decreased. Therefore, the variations of properties changed except for water absorption and total porosity, which manifested a continuous decline.

Processing, Mechanical, and Thermal Properties of Polypropylene/Rattan Powder/Talc Hybrid Composites

Talc was incorporated as filler alongside rattan powder in polypropylene (PP) matrix to produce a hybrid composite. 20 phr of rattan powder was used for all samples. Talc filler loadings were varied from 0 to 10 phr. The composite was manufactured using a Polydrive Thermo Haake internal mixer, which provided processing characteristics for the composite. Peak and stabilization torques gradually increased with increasing talc filler loading. Tensile properties of the hybrid composites showed an increase in tensile modulus and a decline in elongation at break with increasing talc loading. The tensile strength was enhanced with the addition of talc up to a loading of 4 phr and then decreased with further talc filler loading. A water absorption test was carried out, whereby the water uptake of the hybrid composites was reduced with higher talc filler loading. Thermal degradation of the composites was analyzed by studying thermogravimetric analysis (TGA) thermograms and derivative thermogravimetry (DTG) curves, which showed improvement in the thermal stability of the composite with higher talc content. The morphological studies carried out on tensile-fractured surfaces of the hybrid composites explained the enhancement and deterioration of tensile properties with regard to different filler loadings.

Improving the de-agglomeration and dissolution of a poorly water soluble drug by decreasing the agglomerate strength of the cohesive powder

Influence of ternary, poorly water-soluble components on the agglomerate strength of cohesive indomethacin mixtures during dissolution was studied to explore the relationship between agglomerate strength and extent of de-agglomeration and dissolution of indomethacin (Ind). Dissolution profiles of Ind from 20% Ind-lactose binary mixtures, and ternary mixtures containing additional dibasic calcium phosphate (1% or 10%; DCP), calcium sulphate (10%) and talc (10%) were determined. Agglomerate strength distributions were estimated by Monte Carlo simulation of particle size, work of cohesion and packing fraction distributions. The agglomerate strength of Ind decreased from 1.19 MPa for the binary Ind mixture to 0.84 MPa for 1DCP:20Ind mixture and to 0.42 MPa for 1DCP:2Ind mixture. Both extent of de-agglomeration, demonstrated by the concentration of the dispersed indomethacin distribution, and extent of dispersion, demonstrated by the particle size of the dispersed indomethacin, were in descending order of 1DCP:2Ind>1DCP:20Ind>binary Ind. The addition of calcium sulphate dihydrate and talc also reduced the agglomerate strength and improved de-agglomeration and dispersion of indomethacin. While not definitively causal, the improved de-agglomeration and dispersion of a poorly water soluble drug by poorly water soluble components was related to the agglomerate strength of the cohesive matrix during dissolution.