Acrylic Dental Composites for Dentures and Adhesives Mechanical Propreties Modified Using Alumina, Silica and Composite LDH@silica Particles

An overview of advanced composite materials based on thermoplastic polymers for use in dentistry as basic materials for dentures and other industrial applications has been made. These advanced composite materials are reinforced using various oxide fillers. Alumina based particles were prepared from aluminium chloride hydroxide as starting material by sol-gel technique. One series of particles was doped with ferrous oxide. Both series of particles were calcinated at three different temperatures: 700 °C, 800 °C and 900 °C. It was investigated whether and how the calcination temperature of particles affects the microhardness and mechanical properties of composites. Another type of filler used were silica particles obtained from rice husk, as well as silica particles to which, double hydroxide particles were deposited as surface modifiers. The prepared particles were used in amounts of 1, 3 and 5 wt. % as reinforcing agents. Characterization of the synthesized particles was performed by X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy with EDS. The development and synthesis of two acrylate matrices are presented. One of the matrices used is polymethylmethacrylate (PMMA) which has been thermally polymerized and used for denture materials. The mechanical properties of PMMA composites, such as hardness, impact resistance, tensile test and toughness of the material, were investigated. Photopolymerizable acrylates such as Bis-GMA (bisphenol A glycidyl methacrylate)/TEGDMA (triethylene glycol dimethacrylate) were used for the second type of matrix. This matrix was used to test the adhesion between a composite film with given particles as reinforcements on a metal surface. Three different methods were used to test adhesion: determination of film hardness and quantitative assessment of bond strength according to Chen Gao model; wetting angle between composite and substrate determination; and cavitation testing. The mechanical properties of composite materials are improved by increasing the reinforcement content. It is proved that the adhesion is improved with addition of the fillers

Comparison of Quantitative and Qualitative EDXRF Analysis for Provenance Study of Archaeological Ceramics

The most common scientific analysis of archaeological ceramics aims to determine the raw material source and/or production technology. Scientists and archaeologists widely use XRF-based techniques as a tool in a provenance study. After conducting XRF analysis, the results are often analyzed using multivariate analysis in addition to interpretation and conclusions. Various multivariate techniques have already been applied in archaeological ceramics provenance studies to reveal different raw material sources, identify imported pieces, or determine different production recipes. This study aims to evaluate the results of multivariate analysis in the provenance study of ceramics that belong to three cultures that settled in the same area during various prehistoric periods. Portable energy-dispersive X-ray fluorescence spectrometry (pEDXRF) was used to determine the elemental composition of the ceramic material. The ceramic material was prepared in two different ways. The ceramic body material was ground into powder, homogenized, and then pressed into tablets. After that, the same fragments are polished in suitable places. Quantitative and qualitative analyses were performed on the tablets and polished pieces. The results were subjected to both unsupervised and supervised multivariate analysis. Based on the results, it was concluded that qualitative analysis of the well-prepared shards’ surface using EDXRF spectrometry could be utilized in provenance studies, even when the ceramic assemblages were made of similar raw materials

Microhardness measurement optimization in green derived silica/polyester composites using response surface methodology

Polymer composites based on unsaturated polyester resin (UPR) and reinforced with particles based on unmodified/modified plant provenance biosilica particles were synthesized and characterized. An unsaturated polyester resin was obtained from waste poly (ethylene terephthalate (PET). Biosilaca particles are made from rice husk biomass. The surface of the produced silica particles was modified using three different silanes: 3-trimethoxysilylpropyl methacrylate (MEMO), trimethoxyvinylsilane (TMEVS), and 3-aminopropyltrimethoxysilane (APTMS). The microhardness test method was used to investigate the mechanical properties of synthesized composite material with variations in dwell times and applied loads. Optimization of composite microhardness value prediction in function of synthesized parameters (type of modification of silica particles) and measurement parameters (applied loads and dwell times) was done using the method of response surface methodology (RSM) regression analysis. The maximal microhardness values (0.459 GPa) were obtained of type modification of silica particles with vinyl with 80% confidence for 120 experimental variables. This method can be used to choose the optimal dwell time and load for comparison of measurements between different composite materials and to enable the choice of the material in terms of optimization of the quality of reinforcement and quality of interphase determined by surface modification

The Use of Image Analysis for Determination of Surface Deterioration Level of Improved Alumina Based Materials Subjected to Cavitation

Alumina based specimens having different content of alumina based fibers were investigated for possible application as cavitation resistant material. Cavitation damages of the alumina based specimens were tested by the modified vibratory cavitation set up. Erosion rates were measured based on the method developed for metallic samples, mass loss was measured during the experiment. Surface erosion was determined during the experiment simultaneously to mass loss measurements. Image Pro Plus Program was applied for surface analysis during testing. Results indicate that investigated material exhibit excellent mechanical properties and very good resistance to cavitation erosion

Lasersko čišćenje tekstilnih eksponata sa korodiranim metalnim nitima - optimzacije parametara procesa

This paper presents the results of the laser cleaning effects on textile samples with corroded metallic threads. In many museum collections, there are textile exhibits like uniforms, national costumes, flags and home textile, embroidered with metallic threads. Corrosion of metal threads is one of the most common problems that damage embroidered items. In the practice, the application of conventional cleaning methods rarely gives the expected results, and the implementation of laser technology was the next step for corrosion products cleaning. The Nd:YAG laser was used to clean the corrosion of embroidered items from a museum study collection. The effects on the laser irradiated zones were investigated by optical and SEM microscopy and the EDX analysis. The laser irradiation process parameters of the metal threads corrosionU radu su prikazani rezultati čišćenja korozije na tekstilnim eksponatima sa metalnim nitima pomoću lasera. U mnogim muzejskim zbirkama nalaze se eksponati kao što su uniforme, narodne nošnje, zastave i kućni tekstil, ukrašeni vezom metalnim nitima. Korozija metalnih niti je jedan od najvećih problema, koji oštećuje vezene eksponate. U praksi, veoma često, klasične metode ne daju očekivane rezultate i primena lasera je sledeći korak čišćenja korozionih produkata. Nd- YAG laser je korišćen za čišćenje korozije vezenih eksponata iz muzejske, studijske zbirke. Efekti u zonama ozračenim laserom su ispitivani optičkim mikroskopom, SEMom i EDX analizom. Određeni su izabrani parametri za uspešno i bezbedno čišćenje korozije na metalnim nitima.В этой статье приведены результаты очистки коррозии на экспонатах из текстиля с металлическими нитями с помощью лазера. Во многих музейных коллекциях представлены экспонаты, такие как формы, народные костюмы, флаги и домашний текстиль, вышитые металлической нитью. Коррозия металлических нитей является одной из самых больших проблем, которая повреждает вышитые экспонаты. На практике, очень часто, классические методы не дают ожидаемых результатов и применение лазера является следующим шагом очистки следов коррозии. Nd-YAG лазер используется для очистки коррозии вышитых экспонатов из музейных исследовательских коллекций. Эффекты в областях облученных лазером были исследованы с помощью оптического микроскопа, SEM и EDX анализом. Некоторые параметры определяются и выбираются так, чтобы успешно и безопасно очистить металлические нити от коррозии.Dans ce papier on a présenté les résultats du nettoyage de corrosion chez les objets exposés en textile aux fils métalliques réalisé au moyen du laser. Dans plusieurs collections de musée on trouve les objets tels que uniformes, costumes nationaux, drapeaux et textile de maison qui sont ornés de broderie faite en fils de métal. La corrosion des fils en métal est un des plus grands problèmes car elle endommage les objets exposés brodés. En pratique les méthodes classiques ne donnent pas souvent les résultats espérés et l’utilisation du laser est le pas suivant dans le nettoyage des produits de corrosion. Le laser Nd-YAG a été utilisé pour le nettoyage de corrosion sur les objets brodés appartenant à la collection d’étude de musée. Dans les zones irradiées par laser les effets ont été étudiés au moyen du microscope optique et en utilisant les analyses SEM et EDX. On a déterminé les paramètres choisis pour le nettoyage en sécurité et avec succès de la corrosion chez les fils en métal

Mechanical Properties of Composite Material Reinforced With Silica Particles Obtained from Biomass Modified With Double-Layered Hydroxides

Silica particles were produced form rice husk and used as reinforcement in the polymer matrix. The obtained silica particles' surfaces were modified with layered double hydroxides, which enabled better reinforcement in the PMMA matrix. Coprecipitation was used to synthetize Fe Al layered double hydroxides (LDH) with a Fe:Al cation content of 3:1 and an FeAl-LDH: silica ratio of 1:1. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with EDS were used to characterize the synthesized particles. The prepared particle amounts in the PMMA matrix were 1, 3, and 5 wt. %. The purpose of this study was to see if the obtained SiO2 particles, as well as their modification with FeAl-LDH, had any effect on the mechanical properties of polymer composite materials. The mechanical characterization of obtained composites was done using Vickers microindentation tests and impact testing. The Vickers micro-hardness test showed that the addition of reinforcement increases the hardness of the composite. When compared to the matrix, the toughness of the composite material with a higher content of particles (5 wt. %) in the energy absorbed in this impact test was three times higher.The book of abstract available at: [http://conf.univerzitetpim.com/wp-content/uploads/2022/06/Book-of-Abstracts_2022-1.pdf

Surface hydrophobization of handmade paper

U ovom radu su predstavljene mogućnosti povećanja hidrofobnosti površine papira nanošenjem slojeva hidrofobnog materijala na njegovu površinu. Ispitane su dve različite tehnike nanošenja stearinske kiseline, šelaka i cink-hidroksida na površinu papira. Hidrofobnost je ispitana modifikovanom metodom po Kobu, merenjem ugla kvašenja i vremena zadržavanja kapi. Prisustvo sredstava za hidrofobizaciju potvrđeno je FTIR spektroskopijom. Utvrđeno je da se, primenjenim metodama nanošenja, mnogo bolji rezultati dobijaju sa stearinskom kiselinom nego sa šelakom.The paper shows the possibilities of increasing the hydrophobicity of the paper surface by applying layers of hydrophobic material to the surface. Various application techniques and the following substances were tested: stearic acid, shellac and zinc-hydroxide. Hydrophobicity was tested using the modified Cobb method, measuring the contact angle and drop retention time. The presence of hydrophobizing agents was confirmed by FTIR spectroscopy. It was found that the methods of applying the hydrophobizing agent, used in this work, give much better results with stearic acid, compared to shellac. This manuscript presents novel possibilities of increasing paper surface hydrophobicity by applying layers of hydrophobic material to the surface. Various layer application techniques were examined, as well as substances including: stearic acid, shellac and zinc-hydroxide. Hydrophobicity was tested using the modified Cobb method, measuring the contact angle and drop retention time. The presence of hydrophobizing agents was confirmed by FTIR spectroscopy. Based on the results achieved, it can be concluded that the methods of applying the hydrophobizing agent, used in this work, give much better results with stearic acid, compared to shellac

Surface hydrophobization of handmade paper

U ovom radu su predstavljene mogućnosti povećanja hidrofobnosti površine papira nanošenjem slojeva hidrofobnog materijala na njegovu površinu. Ispitane su dve različite tehnike nanošenja stearinske kiseline, šelaka i cink-hidroksida na površinu papira. Hidrofobnost je ispitana modifikovanom metodom po Kobu, merenjem ugla kvašenja i vremena zadržavanja kapi. Prisustvo sredstava za hidrofobizaciju potvrđeno je FTIR spektroskopijom. Utvrđeno je da se, primenjenim metodama nanošenja, mnogo bolji rezultati dobijaju sa stearinskom kiselinom nego sa šelakom.The paper shows the possibilities of increasing the hydrophobicity of the paper surface by applying layers of hydrophobic material to the surface. Various application techniques and the following substances were tested: stearic acid, shellac and zinc-hydroxide. Hydrophobicity was tested using the modified Cobb method, measuring the contact angle and drop retention time. The presence of hydrophobizing agents was confirmed by FTIR spectroscopy. It was found that the methods of applying the hydrophobizing agent, used in this work, give much better results with stearic acid, compared to shellac. This manuscript presents novel possibilities of increasing paper surface hydrophobicity by applying layers of hydrophobic material to the surface. Various layer application techniques were examined, as well as substances including: stearic acid, shellac and zinc-hydroxide. Hydrophobicity was tested using the modified Cobb method, measuring the contact angle and drop retention time. The presence of hydrophobizing agents was confirmed by FTIR spectroscopy. Based on the results achieved, it can be concluded that the methods of applying the hydrophobizing agent, used in this work, give much better results with stearic acid, compared to shellac

Using magnesium ferrite catalyst for degradation of acid violet 109 from aqueous solution by heterogeneous Fenton process

Organic pollutants and their residues formed after various technological processes can be found all around us (in soil, watercourses, and air). The textile wastewaters contain many hazardous substances which have carcinogenic and mutagenic effects on living organisms. The study divides into two parts; the first part is dedicated to the synthesis and characterization of catalysts, and the second part describes the decolorization of AV 109 solution by the heterogeneous Fenton process using magnesium ferrite as a catalyst. The catalysts are synthesized by the sol-gel technique and sintered at different temperatures (500, 600, and 700 °C). Scanning Electron Microscopy reveals the morphological structure of the ferrite-based catalysts, and the size and form of the used catalysts can describe using some shape factors. Elemental analysis of the supported catalyst surfaces revealed by Scanning Energy Dispersive Spectroscopy. The effect of dye's, hydrogen peroxide's and catalyst's concentrations, pH value, and type of catalyst, on dye removal by the Fenton process was studied. The change of AV 109 concentration during the decolorization was followed using the UV-Visible spectrophotometer

Adsorption of anthraquinone dye acid violet 09 from aqueous solution using synthesized alumina-iron oxide doped particles

One of the promising methods for wastewater treatment is adsorption. This study investigated the adsorption of anthraquinone dye Acid violet 109 from water solution using the alumina- iron oxide doped particles prepared by sol-gel method and sintered at 800 °C. The adsorbent morphology and distribution of diameter of the particles were revealed by Scanning Electron Microscopy and Energy Dispersive Spectroscopy. In the second part, the effect of initial dye's and adsorbent's concentrations and pH value on dye adsorption was studied. Also, the kinetic study of dye adsorption covers the pseudo-second-order and intra-particle diffusion. The change of AV 109 concentration during the adsorption was followed using the UV-Visible spectrophotometer. The adsorption kinetics is in accordance with the pseudo-second-order kinetics model. After 60 minutes of treatment, at the initial dye's concentration of treatment, at the initial dye's concentration of 50 mg dm–3 using the alumina-iron doped particles adsorption efficiency was 51.3% and the value of adsorption capacity is 2.64 mg g –1. The adsorption rate was 0.122 g mg–1 min–1