Fluorescence Lifetime Phasor Analysis and Raman Spectroscopy of Pigmented Organic Binders and Coatings Used in Artworks

Fluorescence analysis of materials used as binders and coatings in artworks is often hampered by numerous factors, leading to uncertainties in data interpretation. Fluorescence lifetime (FL) measurements enable improvement of the specificity with respect to steady-state measurements by resolving the decay dynamics of the fluorophore emissions. In this work, layers of natural resin, oil, and wax—in pure form, pigmented, in mixtures, and spread on different substrates—were analyzed using a compact, portable, fiber-based FL instrument. FL data were processed via the phasor method and integrated with Raman spectroscopy to obtain complementary chemical information on the different substances. It was observed that the τ-phase of the mixtures is affected by both the pigments and the dispersing medium, and that the presence of the metal substrate contributes to changes in the FL of mixtures. The results obtained with our portable FL system combined with Raman spectroscopy pave the way for a systematic study of a larger number of materials for future in situ applications on works of art.

Nanomaterial Antibacterial Technology in the Design of Antibacterial Fabrics for Sports Clothing

In recent years, nanomaterials have been widely used in sports equipment, and their application in sportswear has also attracted wide attention. This research mainly discusses the application of nanomaterial antibacterial technology in the design of antibacterial fabrics for sports apparel. The method of adding nano-TiO2 to the antibacterial textiles varies with the type of fiber or fabric, and the finishing method also changes accordingly. For chemical fibers, the method of blending spinning is mainly used. By adding nano-antibacterial particles in the spinning solution, the polymer is ejected from the spinneret to make antibacterial fibers. This processing method is characterized by good antibacterial durability. The preparation of antimite finishing agent is mainly the dispersion of nanopowder. The selection of the best dispersant is mainly determined by measuring the change of the volume sedimentation rate of TiO2 after 5 days under different dosage and pH value of each dispersant. Then, the particle size of nano-TiO2 and Ag in different dispersing conditions was tested by TEM, and finally, the best dispersing agent and dispersing process were determined. The optimum of nano-antimite and antibacterial finishing agent is as follows: the dispersing agent is TW-80, the amount of anhydrous ethanol in dispersing medium is 5 times that of powder, the amount of dispersing agent is 1.5 times that of powder, the pH value is 7, and the stirring time is not less than 30 min. In the preparation of nano-antimite and antibacterial finishing agent, nanomaterials were used. The weight of nano-TiO2 powder was 20 grams and that of Ag was 20 grams. The dispersion medium (absolute ethanol) was 100 mL of dispersant. The amount of TW-80 was 30 g, the amount of citric acid was 60 g, the emulsion was very stable, and there was only a small amount of precipitation after being static for 5 days. Considering the characteristics of silk knitted fabric, this experiment uses the exhaustion method in the finishing process to finish the silk knitted fabric. After 50 times of washing, the antibacterial rate of Staphylococcus aureus and Escherichia coli reached 95.13% and 87.44%, respectively. This study provides guidance for the application of nanomaterials in the antibacterial field of sports clothing.

Improving the Storage of Some Food Categories to Reduce the Irretrievable Losses of a Retailer: Methodology Analysis

Retailers conventionally store perishable foods in refrigerated display cases to keep them at specific temperatures; air conditioning dries the air in the room, which in turn causes these foods to lose moisture. Water as a dispersing medium and a solvent affects the consistency, structure, and appearance of foods in storage. However, excessive moistness will also jeopardize the quality of foods by providing fungi and bacteria with good conditions for growth. Conventional food storage technology does not involve humidity control; as a result, food appearance and quality degrades, and the intensive food drying results in excessive shrink-related costs to the retailer. To minimize the negative impact of such overdrying of perishable foods on the retailer’s economy, storage facilities must provide optimal temperature and humidity. In this research, the author monitor and compare the write-offs labeled as ‘defective’ and the irretrievable shrink-related losses to identify and analyze the effectiveness of humidity control-enabled refrigeration units when used to store some foods categories in refrigerated display cases.

Preparation and Property of Waterborne Polyurethane/Cellulose Nanofiber Nanocomposite Films

Waterborne polyurethane (WPU) is a new type of polyurethane system, which using water instead of organic solvent as dispersing medium. Because of its non-toxicity and environmental safety, WPU is considered as the development direction of coatings and adhesives. However, the mechanical properties of WPU are worse than that of solvent-based polyurethane, therefore, the modification of WPU has received increasingly attention. Meanwhile numerous evidences demonstrate the excellent properties of cellulose nanofibers (CNFs) such as high aspect ratio, low weight and outstanding mechanical strength. Therefore, there is a high expectation for CNFs to be introduced into WPU as reinforcing filler. In this work, a series of CNFs/WPU nanocomposite films were prepared by solution blending. The structure, morphology, thermal behavior and mechanical properties were investigated. SEM results showed that CNFs were evenly dispersed in the WPU matrix. Tensile tests indicated that the modulus and tensile strength of CNFs/WPU nanocomposite films were improved compared with the neat film. While the break elongation of the nanocomposite films decreased with the increase of CNFs content. The synergistic interaction between CNFs and WPU matrix plays an important role in the enhancement of mechanical properties.

Influence of nanomodifiers on the properties of carbon composites

The properties of carbon composites depend on the interaction at the “filler-matrix” phase boundary. One of the most effective ways to increase interphase adhesion is the introduction of modifying nanoadditives into the matrix. By reinforcing the matrix, the mechanical properties of the carbon composite can be improved.We conducted the analysis of various nanomodifiers of the nanocarbon family, which includes fullerenes, nanotubes, graphenes, and nanodiamonds. Unique characteristics combined with moderate cost price and commercial availability distinguish well nanodiamonds from other nanoparticles. The paper demonstrates the feasibility of modifying the HUNTSMAN epoxy binder with nanodiamonds having a small and uniform size, a spherical particle shape, and an accessible outer surface. We present the technology of introducing nanodiamonds into an epoxy binder and manufacturing of carbon composites on its basis. Nanodiamonds were introduced into the light-flow solvent tetrahydrofuran under the influence of ultrasound providing a good dispersing medium. To determine the optimal content of nanomodifiers, allowing to increase interfacial adhesion, a multi-component epoxy binder HUNTSMAN based on Araldite LY556 resin, Aradur 917 hardener, and Accelerator DY 070 accelerator was investigated with nanodiamonds content of 0.26, 0.52, 2.6, 5.2, and 10.4 wt. %. We found that the introduction of nanodiamonds in an amount of 2.6 wt. % allows us to increase the hardness of materials up to 50 %. We show that introducing a minimum amount of nanomodifiers, containing up to 0.26 wt. %, into the epoxy binder gives a maximum increase in the strength characteristics of nanomodified carbon composites up to 18 %. The work was carried out under the Horizon-2020 grant agreement.

Investigation of the concentration- and temperature-dependent motion of colloidal nanoparticles

Laser speckle imaging is used to study the influence of concentration and temperature on the motion of suspended gold nanoshells. Long-range interparticle interaction and viscosity of the dispersing medium sizeably affect the diffusion velocity.

Characterization and determination of thermal and radioluminescence properties of low-density polyethylene (LDPE)-(nanozeolite + Y2O3) composite

Nanotechnology has become one of the most popular areas of interdisciplinary research. In the vast majority of nanotechnology applications, polymer-based matrices were used as the dispersing medium of nanoparticles. The combination of polymer–zeolite nanocomposite has the potential to come out with the advantages of polymers and zeolites while coping with the deficiencies of both materials. In this study, the synthesis and properties of low-density polyethylene (LDPE) composites with nanozeolite + Y2O3 are investigated. Polyethylene nanocomposite fibers containing nanozeolite + Y2O3 at 5% by mass using a melt extrusion method were composed in a laboratory type twin screw extruder. The thermal properties of the composite fibers were determined by analysis of both thermal gravimetric and differential thermal spectra. Their structural properties were enlightened by scanning electron microscopy, Fourier transform infrared, and ultraviolet absorption. According to the results of X-ray diffraction tests, the samples contain crystals in semicrystalline and α form. The mechanical properties of LDPE matrices increased with the addition of nanoparticles. In addition, radioluminescence properties of the polymer were also improved after composing with nanozeolite and Y2O3.

The Effect of Cellulose Nanocrystal Coatings on the Glass Fiber–Epoxy Interphase

This study focuses on understanding the effect of cellulose nanocrystals (CNCs) on glass fiber/epoxy interfacial interactions. The glass fibers (GF) were coated with solutions containing cellulose nanomaterial. The parameters that were investigated were the CNC surface chemistry, concentration, and dispersing medium, i.e., aqueous solution only versus emulsions. To determine the effect of the CNC coatings on the interfacial adhesion, specimens of a single GF in an epoxy matrix were prepared for GF coating by varying the coating formulations. The interfacial shear stress (IFSS) was determined by the single fiber fragmentation test (SFFT). Following the SFFT, the samples were investigated by cross-polarized microscopy in order to understand the fracture modes which are related to the nature of the interphase. According to the SFFT data and photoelastic fracture patterns, both the emulsion and aqueous coatings containing cellulose nanocrystals functionalized with methyl(triphenyl) phosphonium (CNCPh) improve the IFSS in comparison to coated GFs without CNCs.

Nano-lignocellulose from recycled fibres in coatings from aqueous and ethanolic media: effect of residual lignin on wetting and offset printing quality

Nano-lignocellulose (NLC) and lignin-free nanocellulose (nano-holocellulose, NHC) were used in paper coating to investigate their effect on coating layer quality and offset printing. The NLC was produced by microfluidisation of unbleached secondary fibres while the reference NHC was obtained from the same fibre source after lignin removal (OHEPH bleaching), following the same mechanical process. TEMPO-mediated oxidation of the fibres prior to microfluidisation was applied to increase the electrostatic charge and hydrophilicity of the nanofibrils. The coatings, displaying given surface morphology and energy, were applied on Kraft, printing-grade papers at three grammage levels. The structure of the coated and uncoated (reference) papers were accessed (SEM and AFM) and IGT printing was carried out to determine the print density, print gloss, rub-off resistance, surface energy, roughness, ink transfer, dry pick resistance, water interference and set-off. The results highlight the important effect of residual lignin or type of nanocellulose on the coating layer and the development of offset printing properties. It was observed that roughness was a key factor leading to a deterioration of the print properties, predominantly affecting the NLC coating. Considering the lower hydrophilicity of NLC, an alternative dispersion with water-alcohol mixtures is proposed. By using this dispersing medium, tailorable surface coverage, surface smoothness, ink acceptance and improved printability was achieved. We show that under these conditions and compared to NHC, NLC is equally effective as a coating layer.