Application of Activated Carbon Adsorbents Prepared from Prickly Pear Fruit Seeds and a Conductive Polymer Matrix to Remove Congo Red from Aqueous Solutions

The present work was aimed to evaluate the adsorption properties of activated carbons based on prickly pear seeds (PPS) and conductive polymer matrix based on polyaniline (PANI) for the removal of anionic Congo red (CR) dye from aqueous solutions. The adsorbent was prepared by polymerization of aniline in the presence of activated PPS by phosphoric acid and sodium hydroxide. The samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and the Brunauer–Emmett–Teller (BET) methods. The adsorption kinetics were studied using UV-visible (UV/Vis) spectroscopy. The characterization data suggest that the adsorption of the Congo red dye is enhanced because PANI chain molecules, which are especially accountable for removal through π—π interaction and H-bonding with the CR, are adsorbed/tethered onto the acid-activated PPS (PPSH), and thus surmount the mass transfer limitation by being best exposed to the CR-adsorbed molecule. The adsorption kinetics follows the pseudo-second order process. The correlation coefficients (R2) for Langmuir, Freundlich and Tempkin showed that the adsorption values obey Freundlich and Tempkin isotherm models. Moreover, the isotherm was most accurately described by the Freundlich model, and the maximum removal percentage was calculated to be 91.14% under optimized conditions of pH 6.6, 1 g/L of adsorbent dosage, and an initial CR dye concentration of 20 mg·L−1. Importantly, the hybrid adsorbent exhibited the highest adsorption capacity (80.15%) after five cycles of the adsorption–desorption process. Thermodynamic parameters, such as entropy changes, enthalpy changes and Gibbs free energy, were also evaluated. These results indicated that the PANI matrix can generally be better utilized for the removal of Congo red dye when appropriately dispersed on the surface of suitable support materials. These results provide a new direction to promote the separable adsorbents with increasing performance for adsorption of dye impurities from wastewater.

Reinforcement of Protective Coatings Based on Powder Paints with Alumina Nanofibers

The paper deals with the production and study of nanocomposite powder paints based on alumina nanofibers. For nanodispersed fillers, the nature of the surface states on the filler particles is important. The problem of introducing nanomaterials into a polymer matrix cannot provide an effective solution without matching the surface states of the nanomaterial filler and the polymer matrix for the resulting composite materials. The consistency of the surface states of the nanomaterial filler and the polymer matrix determines the quality of transfer of the necessary properties to the resulting polymer composite. In order to increase the affinity of alumina nanofibers with a matrix of powder paint, the nanofibers were treated with 3-glycidyloxypropyltrimethoxysilane (GLYMO) in toluene. It is shown in the work that the addition of alumina nanofibers leads to a hardening of the coating, an increase in its elasticity, and an increase in corrosion resistance. Finishing of alumina nanofibers in a solution of silane in toluene leads to its functionalization, which is sufficient for the distribution of nanofibers in the polymer matrix of the paint and improvement of its operational properties.

Development and Mechanical Testing of Carbon Fiber Reinforced Polymer Matrix Composites for Micro Wind Turbine Applications

In this century, composites have been discovered to be the most promising and discriminating material accessible. Composites reinforced with synthetic or natural fibres are becoming more popular as demand for light weight, high strength materials for specialized applications grows are on the rise in the market. In the current work Carbon fiber Reinforced Polymer Matrix Composite material is developed aiming wind turbine blade applications. This research demonstrates the successful development of a carbon fibre reinforced Epoxy matrix composite that can be utilized to make micro wind turbine blades and is very cost effective thanks to the utilization of a simple hand lay-up approach. The peak elongation varies from 12.248 mm to 14.417 mm, and the tensile strength varies from 939.472 N/mm2 to 960.910 N/mm2. It was observed that the Compressive Strength varies from 8.992 N/mm2 to 46.895 N/ mm2 and peak elongation varies from 1.808 mm to 3.462 mm. In three-point bending test, the peak load was found to be 509.96 N. Due to the presence of carbon fibre reinforcement, the bending strength of polyester resin has been greatly increased.

Options to Improve the Mechanical Properties of Protein-Based Materials

While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.

РОЗРОБЛЕННЯ ПРОГРАМНОГО ЗАБЕЗПЕЧЕННЯ ДЛЯ ОЦІНЮВАННЯ ОДНОРІДНОСТІ РОЗПОДІЛУ НАПОВНЮВАЧА В ПОЛІМЕРНІЙ МАТРИЦІ

Purpose. Creation of software for evaluating the uniformity of distribution of the filler in a polyethylene matrix.Methodology. Software development was carried out using the Python programming language and libraries: PIL, Numpy, Matplotlib, Xlsxwriter. The suitability of the developed software for use was determined by verifying it. During this verification, polyethylene compositions filled with colloidal graphite in the form of compressed films were evaluated. To obtain these compositions, we chose P6006AD grade polyethylene and C-1 colloidal graphite. Samples of polyethylene compositions were obtained in two stages: 1) obtaining a strand by extrusion; 2) additional mixing of the composition on a disc mixer and pressing the obtained compositions into a film.Findings. The software has been developed to assess the uniformity of the distribution of the filler in the polyethylene matrix. The data were established on the dependence of the coefficient of heterogeneity of polyethylene compositions on the content of colloidal graphite with use of the developed software. The increase in the content of the filler leads to a decrease in its heterogeneity. It is shown that this effect can be explained by the structuring of the filler in the polyethylene matrix. Despite the formation of aggregates in polyethylene compositions, a significant amount of small colloidal particles of graphite is located between the aggregate space. This leads to a certain leveling of the concentration in the film and reduces its inhomogeneity.Scientific novelty. The influence of the content of colloidal graphite on the homogeneity of polyethylene compositions is determined. It is shown that with an increase in the graphite content from 0 to 20% vol. the coefficient of heterogeneity of the composition decreases from 5.3% to 3.9%, which is due to the structuring of the filler in the polyethylene matrix.Practical value. Software that makes it possible to evaluate the uniformity of the distribution of filler particles in a polymer matrix, and can be used to study the quality of mixing of polymer composite materials has been developed.

Preparation and Properties of Thermoplastic Polyurethane Composites Filled with Powdered Buckwheat Husks

Bio-based fillers for the polymer composites are still interesting from the scientific and industrial point of view, due to their low cost and renewable nature. In this work partially green composites were obtained by the mixing of thermoplastic poly(ester-urethane) with the unmodified and modified (by acetylation) grinded buckwheat husks. Obtained biocomposites were characterized in the terms of their chemical structure (FTIR), microstructure (SEM), thermal stability (TGA), thermomechanical properties (DMTA), and selected mechanical properties. The results showed that introduction of grinded buckwheat husks (even if the amount is 60 wt%) permit retaining high values of tensile strength (around 8–10 MPa), but the increasing amount of applied filler is connected with the decreasing of elongation at break. It can result from good interaction between the polymer matrix and the bio-based filler (confirmed by high values of polymer matrix-filler interaction parameter determined from Pukánszky’s model for the tensile strength of composites). The applied chemical treatment results in changing of mechanical properties of filler and composites. Obtained results confirmed the possibility of using powdered buckwheat husks as filler for thermoplastic polyurethane.