Innovative plasticization technique for talc-powder reinforced wheat-starch biomass composite plastics with enhanced mechanical strength

N-methyl-morpholine-N-oxide (NMMO) was initially created as a plasticizer for starch to produce thermoplastic wheat starch. Subsequently, talc powder was used as a reinforcing filler to enhance the mechanical strength of thermoplastic biomass-based composite plastics. The chemical structure, crystal structure, and microscopic morphology were analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Additionally, the thermal properties were explored through thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The hydrated NMMO plasticizer demonstrated an outstanding plasticizing effect on starch, resulting in a composite with remarkable mechanical properties. In fact, the pure thermoplastic wheat starch plasticized with hydrated NMMO exhibited the highest mechanical strength recorded so far, with a tensile strength of up to 9.4 MPa. In addition, talcum powder displayed a noticeable reinforcing effect. When the talcum powder content reached 30 wt%, the targeted composite achieved a tensile strength of 20.5 MPa and a Young's modulus of 177.9 MPa. These values were 118 % and 48 % higher, respectively, than those of the pure thermoplastic starch sample. This innovative plasticizing method opens up a new avenue for the development of high-mechanical-strength thermoplastic biomass-based composite plastics with promising potential applications.

Liquid phase exfoliation of talc: effect of the medium on flake size and shape

Industrial applications of nanomaterials require large-scale production methods, such as liquid phase exfoliation (LPE). Regarding this, it is imperative to characterize the obtained materials to tailor parameters such as exfoliation medium, duration, and mechanical energy source to the desired applications. This work presents results of statistical analyses of talc flakes obtained by LPE in four different media. Talc is a phyllosilicate that can be exfoliated into nanoflakes with great mechanical properties. Sodium cholate at two different concentrations (below and at the critical micelar concentration), butanone, and Triton-X100 were employed as exfoliation medium for talc. Using recent published statistical analysis methods based on atomic force microscopy images of thousands of flakes, the shape and size distribution of nanotalc obtained using the four different media are compared. This comparison highlights the strengths and weaknesses of the media tested and hopefully will facilitate the choice of the medium for applications that have specific requirements.

Geoinspired syntheses of materials and nanomaterials

The search for new materials is intimately linked to the development of synthesis methods. In the current urge for the sustainable synthesis of materials, taking inspiration from Nature's ways to process matter appears as a virtuous approach. In this review, we address the concept of geoinspiration for the design of new materials and the exploration of new synthesis pathways. In geoinspiration, materials scientists take inspiration from the key features of various geological systems and processes occurring in nature, to trigger the formation of artificial materials and nanomaterials. We discuss several case studies of materials and nanomaterials to highlight the basic geoinspiration concepts underlying some synthesis methods: syntheses in water and supercritical water, thermal shock syntheses, molten salt synthesis and high pressure synthesis. We show that the materials emerging from geoinspiration exhibit properties differing from materials obtained by other pathways, thus demonstrating that the field opens up avenues to new families of materials and nanomaterials. This review focuses on synthesis methodologies, by drawing connections between geosciences and materials chemistry, nanosciences, green chemistry, and environmental sciences.

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

This paper presents the liquid crystal (LC) properties of poly(l-lactide) (PLLA). Mesophase behavior is investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The performed analyses confirm that pressed PLLA films exhibit the unique capability of self-assembling into a nematic mesophase under the influence of mechanical pressure, temperature, and time. It was originally demonstrated that the chiral nematic mesophase can be obtained by introducing fine powders into the polymer. Based on the research conducted, it was proved that the pressed PLLA films have a chiral nematic mesophase with a nematic-to-isotropic phase transition and a large mesophase stability range overlapping the temperature of the human body, which can persist for years at ambient temperature. The obtained films show tailor-made properties toward a nematic mesophase with a specific texture, including colored planar texture of the chiral nematic mesophase and blue-phase (BP) LC texture. The BP, described for the first time in plain PLLA, occurred over a wider than usual temperature range of stability between isotropic and chiral nematic thermotropic phases (ΔT ≈ 9 °C), which is an advantage of the obtained polymer material, in addition to ease of preparation. This opens up new prospects for advanced photonic green applications.

Evolution of Black Talc upon Thermal Treatment

Black talc is a natural silicate clay mineral with a typical 2:1 layered structure, low electrical conductivity, large specific surface area, and high thermal stability. The world’s largest black talc mine, with known reserves of one billion tons, is located in China’s Jiangxi province. Due to the restriction of its color, the application of black talc is only limited to ceramic raw materials, coating filler, waterproof materials, and other low-end application industries. Thermal treatment is a common method of clay mineral modification. It is vital to examine the structural and physical changes of black talc during calcination in order to prepare black-talc-based composites and to broaden their applications. This work discusses the evolution of black talc upon thermal treatment (30–1000 °C) and the corresponding structural changes. The thermal stability of minerals was analyzed via thermogravimetric (TG) analysis and thermogravimetry–mass spectrometry (TG-MS). The decomposition of minerals during calcination consists of four processes: dehydration, organic carbon decomposition, dihydroxylation, and phase transformation. In situ FTIR and in situ XRD were employed to track changes in black talc in real time during thermal treatment. At 800 °C, black talc was found to begin to go through dihydroxylation, and the crystallinity index decreased significantly. The XRD pattern of samples at 950 °C (T950) showed the reflection of the enstatite structure, and the relative crystallinity index was 27.3%, indicating that the mineral had undergone phase transformation. In addition, the Brunauer–Emmet–Teller (BET), laser particle size analyzer, Zeta potential, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques were used to systematically characterize the physicochemical properties of minerals at different temperatures. The results show that black talc’s particle size and specific surface area increase with the calcination temperature. The surface charge changes, and more amorphous SiO2 and MgO appear, indicating that thermal treatment could induce structural changes and activate the surface of black talc.

The integrity of synthetic magnesium silicate in charged compounds

Magnesium silicate is an inorganic compound used as an ingredient in product formulations for many different purposes. Since its compatibility with other components is critical for product quality and stability, it is essential to characterize the integrity of magnesium silicate in different solutions used for formulations. In this paper, we have determined the magnitude of dissociation of synthetic magnesium silicate in solution with positively charged, neutral, and negatively charged compounds using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). The EDS results were verified through Monte Carlo simulations of electron-sample interactions. The compounds chosen for this study were positively charged cetylpyridinium chloride (CPC), neutral lauryl glucoside, and negatively charged sodium cocoyl glutamate and sodium cocoyl glycinate since these are common compounds used in personal care and oral care formulations. Negatively charged compounds significantly impacted magnesium silicate dissociation, resulting in physio-chemical separation between magnesium and silicate ions. In contrast, the positively charged compound had a minor effect on dissociation due to ion competition, and the neutral compound did not have such an impact on magnesium silicate dissociation. Further, when the magnesium ions are dissociated from the synthetic magnesium silicate, the morphology is changed accordingly, and the structural integrity of the synthetic magnesium silicate is damaged. The results provide scientific confidence and guidance for product development using synthetic magnesium silicate.

Synthetic ferripyrophyllite: preparation, characterization and catalytic application

Sheet silicates, also known as phyllosilicates, contain parallel sheets of tetrahedral silicate built up by [Si₂O₅]^2- entities connected through intermediate metal-oxygen octahedral layers. The well-known minerals talc and pyrophyllite are belonging to this group based on magnesium and aluminium, respectively. Surprisingly, the ferric analogue rarely occurs in nature and is found in mixtures and conglomerates with other materials only. While partial incorporation of iron into pyrophyllites has been achieved, no synthetic protocol for purely iron-based pyrophyllite has been published yet. Here we report about the first artificial synthesis of ferripyrophyllite under exceptional mild conditions. A similar ultrathin two-dimensional (2D) nanosheet morphology is obtained as in talc or pyrophyllite but with iron(iii) as a central metal. The high surface material exhibits a remarkably high thermostability. It shows some catalytic activity in ammonia synthesis and can serve as catalyst support material for noble metal nanoparticles.

Sustainable valorization of paper mill sludge into cellulose nanofibrils and cellulose nanopaper

As a kind of agro-industrial wastes, paper mill sludge (PMS) has posed serious environmental and economic challenges for disposal due to the more stringent regulations and diminishing land availability in recent years. The present study is aimed at providing a sustainable approach to efficiently convert PMS to cellulose nanofibrils (CNFs) and cellulose nanopaper (CNP) by formic acid (FA) hydrolysis pretreatment and the followed microfluidization. It is found that FA hydrolysis (4-6 h) could swell and shorten PMS fibers, and only two-pass microfluidization is sufficient to get uniform CNFs from the collected cellulose residual. Results indicate that the obtained CNFs show high thermal stability and crystallinity index, surface functionality (ester groups), as well as a high yield of over 75 wt.%. Notably, more than 90 % FA can be recovered and the hydrolyzed sugars could be potentially used to produce platform chemicals (e.g. lactic acid, furfural). Finally, transparent CNP is prepared from the CNFs suspension via a simple vacuum filtration technique. The resultant CNP shows good mechanical properties with the maximum tensile strength and toughness of 106.4 MPa and 6.62 MJ/m³, respectively. Therefore, the current work provides a green and sustainable method to valorize PMS for the production of valuable CNFs and CNP.

Organically modified layered magnesium silicates to improve rheology of reservoir drilling fluids

Petroleum well drilling fluids are one of the most significant constituents in the subterranean drilling processes to meet an increasing global demand for oil and gas. Drilling fluids experience exceptional wellbore conditions, e.g. high temperature and high pressure that adversely affect the rheology of these fluids. Gas and oil well drilling operations have to adjourn due to changes in fluid rheology, since the drilling fluids may lose their effectiveness to suspend heavy particles and to carry drilled cuttings to the surface. The rheological properties of drilling fluids can be controlled by employing viscosifiers that should have exceptional stability in downhole environments. Here, we have developed next-generation viscosifiers-organically modified magnesium silicates (MSils)-for reservoir drilling fluids where organic functionalities are directly linked through the Si-C bond, unlike the industry's traditional viscosifier, organoclay, that has electrostatic linkages. The successful formation of covalently-linked hexadecyl and phenyl functionalized magnesium silicates (MSil-C16 and MSil-Ph) were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Identical drilling fluid formulations were designed for comparison using MSils and a commercial viscosifier. The rheological properties of fluids were measured at ambient conditions as well as at high temperatures (up to 150 °C) and high pressure (70 MPa). Owing to strong covalent linkages, drilling fluids that were formulated with MSils showed a 19.3% increase in yield point (YP) and a 31% decrease in apparent viscosity (AV) at 150 °C under 70 MPa pressure, as compared to drilling fluids that were formulated with traditional organoclay. The higher yield point and lower apparent viscosity are known to facilitate and increased drilling rate of penetration of the fluids and an enhanced equivalent circulation density (ECD), the dynamic density condition, for efficient oil and gas wells drilling procedures.

Inorganic and Hybrid (Organic⁻Inorganic) Lamellar Materials for Heavy metals and Radionuclides Capture in Energy Wastes Management-A Review

The energy industry (nuclear, battery, mining industries, etc.) produces a large quantity of hazardous effluents that may contain radionuclides (¹³⁷Cs and ⁹⁰Sr in particular) and heavy metals. One of the hardest tasks of environmental safety and sustainable development is the purification of wastewater holding these pollutants. Adsorption is one of the most powerful methods for extracting toxic compounds from wastewater. This study reviews the usefulness of clay minerals as adsorbent for removing these hazardous elements to clean up energy production processes. Phyllosilicates are able to extract several heavy metals from effluent, as widely examined. A particular focus is given to synthetic phyllosilicates and their abilities to entrap heavy metals with a special attention paid to those synthesized by sol-gel route. Indeed, this method is attractive since it allows the development of organic–inorganic hybrids from organosilanes presenting various functions (amino, thiol, etc.) that can interact with pollutants. Regarding these pollutants, a part of this review focuses on the interaction of lamellar materials (natural and synthetic phyllosilicates as well as layered double hydroxide) with heavy metals and another part deals with the adsorption of specific radionuclides, cesium and strontium.