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

Application of FeAl-LDH@SiO2 for Phosphate Removal from Water

In present study FEAL-LDH@SIO2 were Used for removing phosphate from aqueous solutions. FeAl-LDH with molar ratio Fe/Al = 3/1 was synthesized by co- precipitation from aqueous solutions in the present of SIO2 PARTICLES. Silica obtained from rice husks were used as a substrate for the deposition of LDH particles. The prepared material was characterized by scanning electron microscope (FE-SEM), X-ray diffraction (XRD), N2 adsorption/desorption isotherms (BET method) and Fourier transform infrared spectroscopy (FTIR). XRD analysis showed that Fe-Al had formed LDH structure. SEM analysis revealed deposition of LDH particles on SIO2 SUBSTRATE. The adsorption characteristics for phosphate uptake of the obtained material were performed. Adsorption experiments were carried out as a function of LDHs dosage with three different mass ratios of LDH/silica = 1/1, 2/1, and 3/1 and different phosphate concentration AT INITIAL PH 4. Phosphate concentrations were determined using spectrophotometer. The results showed that the maximum sorption capacities of phosphates calculated based on Langmuir equation was 52.68 mg g-1.The book of abstract available at: [http://conf.univerzitetpim.com/wp-content/uploads/2022/06/Book-of-Abstracts_2022-1.pdf

Environmental and Community Stability of a Mountain Destination: An Analysis of Residents’ Perception

This study aims to explore the use of the social-ecological system (SES) in tourism of a mountain area. Authors examined residents’ perceptions of tourism impacts on four SES aspects: ecosystems, local knowledge, people and technology and property rights institutions. The aim is to find area that will be a “common ground” for community and area that can be a source of conflict and will require additional work to solve the differences. Second objective was to examine residents’ perception towards future local development tourism policies (winter tourism, seasonality and environment and culture) and how those policies can affect natural, socio-economic and cultural aspects of mountain area. Residents’ perceptions of sustainable tourism development potential, perceivedtourismimpacts,analysisofcommunityattachmentandemploymentsectorofstakeholder were involved in this study. The authors applied the Q-methodology, as one SES-allied approach, in a small mountain community of Kopaonik, the Republic of Serbia. The results revealed that residents’ agreement/disagreement is connected with two aspects: ecosystem and property rights andthatecosystemcanbesignificantlyinfluencedbyallthreedevelopmentpolicies. Findingssuggest that development of future natural conservation plans and new cultural attractions can have positive effects on all parts of social-ecological system. Some practical implications of those findings for tourism planning and development are also discussed

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

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

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

Structural, optical and mechanical characterization of PMMA- MXene composites functionalized with MEMO silane

Processing and characterization of PMMA-MXene composites were investigated. γ-Methacryloxypropyltrimethoxy (MEMO) silane was used to modify the surface of MXenes and improve the compatibility between MXenes and the polymer. The FTIR analysis revealed the formation of a chemical bond between MXene and MEMO silane, while the XPS analysis confirmed the presence of silicon in the functionalized MXene. PMMA composites with non-functionalized and functionalized MXene were prepared using a solution casting method. Tensile tests showed that, compared to neat PMMA, Young’s modulus increased in both composites by 22.1 and 27.6%, respectively. As a result of coupling between the PMMA matrix and the surface-modified MXenes, the tensile strength also increased by about 37%. In addition, optical spectroscopy showed higher absorption for the composite with surface-modified MXenes and short-lived fluorescence with emission intensity sensitive to the crumpling of functionalized MXene nanosheets

Improved technology for production of PE and PP regranulates

Management of waste polymers (polyethylene - PE and polypropylene - PP) represents one of the major obstacles in the field of environmental protection, which demands a most efficient and eco-friendly technological solution. Due to the high use of various plastic materials, the amount of landfilled or dissipated plastic waste is continuously growing. Therefore, this paper examines the possibilities of recycling these polymers, alongside obtaining granules of similar or advanced physico-mechanical characteristics to the commercially available ones. The applied technology consists of several consecutive processes (collecting, grinding, washing and extruding) where the obtained materials can later be incorporated into widely applicable products, such as foils, bin liners, bags, among others. In this way, high-quality products with great market potential are obtained, which will consequently contribute to lower extraction and less depletion of natural resources. Thus major problems may be solved optimally, consolidating the efficiency of improved eco-friendly technologies which is in line with environmental protection and sustainable waste management

Recycled Poly(ethylene Terephthalate) Based-Plasticizer for PVC Regranulates Production

Due to the increasing use and widespread of plastics, poly (ethylene terephthalate) (PET) and poly (vinyl chloride) (PVC) are becoming one of the major threats to the environment. The aim of this paper is obtaining plasticizers from recycled PET, and hot/cold mixing thereof with PVC to produce new materials. Plasticizer was obtained from PET using ethylene glycol (EG) in the presence of catalyst FASCAT 4100, followed by treatment with maleic anhydride and finally 2-ethylhexanol (2-EtHex). The obtained glycolysate and plasticizer, individually or mixtures thereof, were used for the production of polygranulates based on waste PVC in order to obtain an expanded mass of homogenized PVC with glycolysate/plasticizer. The abovementioned procedures and test results for the regranulates and products indicate that the proposed technology offers a solution to the problem of waste PET and PVC through transesterification in order to obtain plasticizer based on PET and EG, called 2-EtHex/MA/РG/PET/EG/MA/2-EtHex used in the processing of PVC waste and in regranulate. The obtained regranulates are further processed by injection molding or extrusion into commercial products such as slippers, footwear, boots, garden hoses, mats, floor mats, etc

Green Plasticizer for Poly(vinyl chloride) Re-Granulate Production: Case Study of Sustainability Concept Implementation

The increase in waste polymer recycling has helped in promoting sustainability, and together with the use of renewable raw materials, it has become a widespread concept with positive effects on both the economy and ecology. Accordingly, the aim of this study was the synthesis of “green” plasticizers, marked as LA/PG/PET/EG/LA, formed from waste poly(ethylene terephthalate) (PET) and bio-based platform chemicals propylene glycol (PG) and levulinic acid (LA). The structure of the obtained plasticizers was complex, as confirmed by results from nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) analysis. The LA/PG/PET/EG/LA plasticizers and waste poly(vinyl chloride) (PVC) were used in an optimized technology for PVC re-granulate production. The hardness of the PVC-based material with “green” plasticizers, in comparison to commercial plasticizer dioctyl terephthalate (DOTP), increased by 11.3%, while migration decreased. An improved material homogeneity and wettability of the fibers by the matrix were observed using SEM analysis of the material’s fracture surface, with a higher efficiency of intermolecular interactions leading to better mechanical performances of the newly designed materials. Thus, LA/PG/PET/EG/LA are unique materials with good compounding and plasticizing potential for PVC, as revealed by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In that manner, the use of bio-renewable resources and recycled polymers will contribute to diminishing waste polymer generation, contributing to a lower carbon footprint