Borax Pentahydrate Research Articles

Boronic ester bonds hydrogel with temperature and pH responsiveness for controlled release fertilizer

The growth of plants can be severely restricted by insufficient water and fertilizers in pure soil. There exists a significant demand for developing a hydrogel to enhance water retention and enable control release fertilizer. In this study, we synthesized the boronic ester bonds hydrogel with temperature and pH responsiveness using sodium alginate, borax pentahydrate and carboxymethyl chitosan (CMCS) via a one-pot method. Urea was loaded in the hydrogel as a model fertilizer. The dual responsive hydrogel exhibited a rapid release behavior of fertilizer due to the dissociation of boronic ester bonds at 40 °C and pH 5.5. The incorporation of CMCS improved the non-covalent interaction within the hydrogel, accompanied by a reduction in the pore size and swelling ratio to 74 μm and 11.3 g/g, respectively. The hydrogel exhibited desirable water retention capacity in soil with a weight loss of only 41.9 % at day 15, while the degradation rate of hydrogel was 49.0 %. Additionally, the hydrogel displayed good antibacterial activity against both Rhizobium and Bacillus cereus strains while being non-toxic to plants. The dual responsive hydrogel holds promising applications in agriculture, forestry, and horticulture.

Determination of the properties of medium-density fiberboards produced using urea-formaldehyde resins modified with boron compounds

Effects of adding different boron compounds to the urea-formaldehyde resin were evaluated relative to the physical, mechanical, and other properties of medium-density fiberboard (MDF). While the chemical addition of boric acid to the urea-formaldehyde resin increased the modulus of rupture and modulus of elasticity values of MDF boards, the physical and chemical additions of other boron compounds decreased those values. While there were no significant decreases in internal bond values, the chemical addition of boric acid and borax decahydrate to urea-formaldehyde resin increased the internal bond values of MDF boards. It was observed that in both types of addition, borax pentahydrate reduced the formaldehyde emission values of MDF boards the most and also reduced the burnt area by up to 30%. When the type of addition of boron compounds to urea-formaldehyde was compared, the addition of boron compounds at the resin formation stage showed better results in the properties of MDF boards than physical addition.

Improving cotton yield and fiber quality in different tropical soils with boron fertilization

AbstractCotton (Gossypium hirsutum L.) is responsive to boron (B) fertilization when there is low soil availability, but the best source and rate to be used and whether this response is dependent on soil texture are still unknown. This study aimed to adjust boron fertilization for cotton as a function of the production environment and B source used. Two field experiments were conducted in the 2020/2021 season in Chapadão do Sul, MS (clayey soil—adequate B content) and Dracena, SP (sandy soil—low B content), Brazil. Treatments consisted of B sources (ulexite [low solubility], borax pentahydrate [BP] [intermediate solubility], and boric acid [BA] [high solubility]), and B rates (0, 1, 2, 4, and 6 kg ha−1) applied to the soil at 25 days after plant emergence. In sandy soil with low B content, application of 2 (high and medium solubility sources) and 4 kg B ha−1 (low solubility source) improved fiber yield between 10% (210 kg ha−1 fiber) and 28% (555 kg ha−1), respectively, as well as micronaire index, strength, elongation, uniformity, and short fibers. Application of B greater than 4 kg ha−1 via soluble sources reduced (between 9% (175 kg ha−1)—BP and 14% (257 kg ha−1)—BA) fiber yield only in sandy soil. When B content in the soil is adequate, B fertilization did not improve yield, but increased fiber strength (4%—1.1 g tex−1) and reduced the short fiber index (16%) by applying 1 kg B ha−1, regardless of the source used. The highest fiber yields were obtained with leaf B contents between 12 and 17 mg kg−1 (sandy soil) and 25 and 27 mg kg−1 (clayey soil). We recommend applying 2 kg B ha−1 (solubility sources) and 4 kg B ha−1 (low solubility source) in sandy soils with low B content to improve yield and fiber quality, and 1 kg B ha−1 in clayey soil with adequate B content to improve fiber quality and replace B amounts removed through harvesting.

Selective separation and recovery of boron from spent Nd-Fe-B magnets leaching solution

The accumulation of boron during the recovery of rare earth elements (REEs) from spent Neodymium-Iron-Boron (Nd-Fe-B) magnets affects the extraction of REEs and causes environmental pollution through the boron-containing wastewater. Given that boron is a globally scarce strategic resource, this study proposes a method for the selective separation and recovery of boron from spent Nd-Fe-B magnets leaching solution. The synergistic extraction of boron adopting 2-ethylhexanol (EHA) and 2-ethyl-1,3-hexanediol (EHD), and the extraction mechanism were investigated. Under optimized conditions (30 % EHA-20 % EHD-50 % sulfonated kerosene, 1:1O/A phase ratio, pH 3.3, 10 min), the two-stage countercurrent extraction achieved a remarkable 99.9 % extraction efficiency with minimal loss of REEs. Slope analysis, Raman, FT-IR, and NMR combined with DFT were used to elucidate the extraction mechanism. Specifically, some of the boric acid molecules complexed with the OH groups of EHD to form stable six-membered ring complexes, while another part bound with both EHA and EHD to form linear complexes containing six-membered rings. Employing 0.4 mol/L NaOH as the stripping agent, the two-stage countercurrent stripping process achieved a stripping efficiency of 99.8 %. Subsequently, borax pentahydrate products exceeding 99 % purity were obtained via evaporative crystallization from the stripping solution. Notably, the raffinate contained only ∼ 5 mg/L of boron, which could be further reduced below the discharge standard via the REEs recovery process, allowing for safe emission. This work offers a novel approach for the selective separation and recovery of boron from spent Nd-Fe-B magnets, eliminating its adverse effects on REEs extraction and the environment, while simultaneously recovering a valuable resource.

The Impact of Incorporating Five Different Boron Materials into a Dental Composite on Its Mechanical Properties

The aim of this study is to comparatively investigate changes in mechanical properties by adding five different types of boron derivatives to a microhybrid dental composite structure. In this study, which evaluated upper and lower surface microhardness (VHN), roughness (Ra), and color stability (∆E), a total of 126 discs were used (n = 7; per each subgroup). All boron derivatives were added to the dental composite structure in equal proportions in a dark room to create experimental composites (5% w/w). To enable comparison, a default composite without the addition of any boron derivative served as the negative control group. Before measurements, all samples were incubated at 37 °C for 24 h. For surface microhardness, roughness, and color stability, all experimental groups were statistically significant within themselves (p < 0.001). The group with borax pentahydrate exhibited the highest VHN value on the upper surface, while the lowest value was observed in the group with etifert. It was found that all experimental groups showed a decrease in lower surface microhardness compared to the control group (p < 0.001). Although the eticol-ceramic-added group had the lowest roughness values, this group also exhibited significantly higher ∆E values compared to the other groups. Surface roughness showed a negative correlation with ∆E and upper surface microhardness values for all experimental groups (respectively p = 0.038; r = −0.185/p = 0.006; r = −0.245). To sum up, the addition of boron derivatives to composites, except for etifert, increased upper surface microhardness values; however, except for eticol-ceramic, surface roughness values also increased. Nevertheless, the addition of boron derivatives, except for eticol-ceramic, ensures color stabilization.

TAVŞAN OMURGASINDA ANTERİOR BODY KAFES BORON UYGULAMASININ KEMİK FÜZYONUNA VE FÜZYON KALİTESİNDE ETKİSİ

OBJECTIVE: Our aim in this study was to demonstrate the effectiveness of hydroxyapatite (HA) and Boron compounds in operations using an Anterior Lumbar Interbody Fusion (ALIF). MATERIAL AND METHODS: In the study, 18 male rabbits of New Zealand breed weighing 2.5-3 kg were used. The animals who were hospitalized on the left side underwent flank incision after surgical cleaning. Lumbar 5-6 distance was reached from the lumbar retroperitoneal region. Following anterior discectomy; ALIF was performed using PEEK (polyethylene ether ketone) cage (Group I) in the control group, PEEK cage and 50 mg/kg boron (borax pentahydrate) (Group II) in the boron group, PEEK cage and 50 mg/kg powder ProOsteon (Group III) in the HA group. The ALIF operation has been applied to all groups. Six weeks later, the animals underwent a computed tomography (CT) scan. Then the lower and upper vertebrae of the sacrificed animals at the distance at which discectomy was performed and the cage was placed were removed, separated for pathology. After being microscopically detected with buffered 10% formaldehyde overnight, the sections prepared from the sample tissues that were routinely followed were stained with hematoxin-eosin and examined histopathologically with light microscopy. RESULTS: While the osteoclast score was 1 in 83.3% of the boron group, it was 2 in 16.6%. In the same group, the osteoblast score was found to be 1 in 50% and 2 in 50%. The osteoclast score of the HA group was 1 in 50%, 2 in 50%, while the osteoblast score was found in 50%, 1 in 2, 2 in 16.6%, and 3 in 33.4%. Higher osteoblast and osteoclast scores were observed in HA group compared to Boron and control groups. It was observed that the boron group had higher osteoblast and osteoclast scores than the control group and lower than the HA group. CONCLUSIONS: Boron and Hydroxyapatite have been shown to form stones of the same size. Although morphologically not as much as boron, hydroxyapatite, histopathological examination showed that it formed a better amount of fusion compared to the control group. The osteoblastic activity was most common in the hydroxyapatite group.

The effect of various boron compounds on the antimicrobial activity of hardened mortars

• Six different boron compounds (5% by mass to cement) were used to prepare cement mortars. • Dicalcium hexaborate pentahydrate (COL) and borax pentahydrate (BPH) were compatible with cement mortars. • COL and BPH addition decreased the flexural and compressive strength values within acceptable limits. • COL and BPH addition inhibited C. albicans and A. niger growth by at least 99%. This study has examined the effect of boron compounds on the mechanical and antimicrobial properties of hardened mortars. The antimicrobial activity of six different boron minerals and compounds was tested against six microorganisms, including Gram-positive and Gram-negative bacteria, yeast, and fungus. Cement mortars containing 5% (w/w) boron mineral addition by weight of cement were exposed to flexural and compression tests on the 7th, 28th and 90th days. At the end of the 90th day, the hardened mortar specimen prepared with 5% dicalcium hexaborate pentahydrate (COL) or 5% borax pentahydrate (BPH) decreased the compressive strength 7.41 % and 31.5 %, and flexural strength 13.5 % and 32 %, respectively. Although, there are decrements in both compressive and flexural strength, values remain within the acceptable limits specified in the material code. The antimicrobial activity of these specimens was evaluated with surface antimicrobial activity tests. The hardened mortar specimen containing boron compounds showed antimicrobial activity against C. albica ns and A. niger . It can be concluded that from these results, using 5 % COL and 5 % BPH as an additive or replacement to the mortar, is an alternative way to create antimicrobial surfaces within environments that have complained of mold problems and biodegradation, such as in reinforced concrete structures or in conventional buildings that need to be free of pathogenic microorganisms.

Bakteriyel selüloz ve boraks katkılı atık gazete kağıtlarının termal ve optik özelliklerinin incelenmesi

Bu çalışmada geri dönüştürülmüş atık gazete kağıtlarından üretilmiş kağıtlara katkı maddesi olarak bakteriyel selüloz (BS) ilavesinin ve kağıdın yanma özelliğini geciktirmek amacıyla boraks pentahidrat (Na2B4O7.5H2O) uygulamasının, üretilen kağıtların termal ve optik özellikleri üzerine etkileri araştırılmıştır. Boraks uygulaması için daldırma yöntemi seçilmiş olup karşılaştırma yapabilmek için üretim esnasında boraks ilavesi de çalışılmıştır. Kağıtların yanma karakteristikleri ve kinetiğini belirlemek için termal özellikleri belirlenmiştir. Optik özellikleri için parlaklık, sarılık ve renk değerleri (L*,a*,b*) belirlenmiştir. TGA verileri değerlendirildiğinde daldırma yöntemi ile boraks uygulaması sonucu dönüm noktası sıcaklığının 377,53 °C’den 335,55 °C’ye düştüğü, sadece BS katkısı ile 379,53 °C’ye bir miktar artış gösterdiği tespit edilmiştir. BS katkılı kağıtların daldırma yöntemi ile boraks uygulaması sonucunda dönüm noktası sıcaklığının 334,24 °C’ye düştüğü ve %44,03 oranı ile diğer örneklere göre en yüksek 590 °C deki kalıntı miktarı verdiği belirlenmiştir. Sonuç olarak daldırma yöntemi ile boraks uygulaması yapılan BS katkılı kağıtların termal dayanımlarının diğerlerine göre daha iyi olduğu, BS ve boraksın kağıdın yanması sırasında kalori oluşumunu azalttığı dolayısı ile yanmayı hızlı bir şekilde sonlandırdığı, optik özellikler açısından BS katkısının ve boraks uygulamasının kağıdın parlaklık değerini azalttığı, sarılık değerini arttırdığı belirlenmiştir.

Effects of Foliar and Soil Boron Fertilization on Yield, Leaf Physiological Traits and Fruit Attributes in Rainfed Almond Orchards

Boron (B) fertilizers are recognized as essential for ensuring yield and fruit quality. However, the importance of soil and foliar B fertilization in almond orchards under rainfed conditions is presently unclear. To address this literature gap, in the present study, the impact of soil and foliar application of B on leaf gas exchange, leaf photosynthetic pigments, yield, and fruit quality in almonds was investigated across three consecutive growing seasons. Boron fertilizer was applied to the soil at four rates (0, 1, 2, and 3 kg ha−1) in the presence or absence of foliar application (0.36 g L−1) of the same micronutrient. Borax pentahydrate was used as the B source. When compared to foliar B fertilization, the soil application of B positively affected the gas exchange parameters, mainly the net CO2 assimilation rate, stomatal conductance, and transpiration rate (percentage of gain between 15% and 80%), but did not influence the chlorophyll content. The almond yield and fruit characteristics were also enhanced (about 25–72%) in response to lower soil B fertilization rates. In the 3 kg ha−1 dose, B had an adverse effect on the yield and resulted in lighter fruits. On the other hand, foliar B fertilization did not benefit any of the evaluated parameters. Overall, these results suggest that, under the studied conditions, almond orchards do not respond to higher B rates in soil or foliar B fertilization.

Life Cycle Assessment of Boron Industry from Mining to Refined Products

Although there are a lot of studies in literature related to the life cycle assessment (LCA) of mining, there are only a few studies done on the boron mining industry. This paper presents an LCA of the boron mining industry including the extraction, beneficiation, and refinement processes. The main purpose is to identify and compare the environmental impacts associated with the production of 1 ton of refined products (boric acid, borax pentahydrate, borax decahydrate, and sodium perborate) starting from an open pit mine located in Turkey. The life cycle inventory (LCI) was obtained from the data collected from the related literature sources and the company’s reports. This cradle-to-gate analysis has been carried out using the commercial software called SimaPro employing the International Reference Life Cycle Data System (ILCD) 2011 Midpoint+ Life Cycle Impact Assessment (LCIA) method. The results showed that the environmental impact of the refinement process is critical compared to the mining and beneficiations processes. Sulphuric acid, steam, hydrogen peroxide, and sodium perborate which are used in refined boron production cause most of the impact and emission into the environment. Among the refined boron products investigated, the impact of sodium perborate is quite high.

Use of colemanite and borax penta-hydrate in soda lime silicate glass melting - A strategy to reduce energy consumption and improve glass properties

In view of recent energy crisis and environmental considerations, reductions of melting temperature and CO2 emissions during the production of commercial soda lime silicate (SLS) glass at industrial scale are major intentions. Here we show that this goal can be achieved by using carbonate-free borate minerals such as colemanite (Ca2B6O11·5H2O) and borax penta-hydrate (BPH, Na2B4O7·5H2O) as alternative sources for CaO and Na2O, respectively. The SLS glass melting temperature has decreased successively by the incorporation of B2O3 with substitution of equivalent wt% SiO2 resulting from gradual utilization of colemanite and BPH. Hot Stage Microscopy (HSM) revealed that the melting temperature was decreased from 1650 °C, for the parent commercial SLS glass, to 1528 °C on use of colemanite and further down to 1072 °C on utilization of both colemanite and appropriate quantity of BPH up to which the properties of the pristine glass can be retained. Thus, energy consumption equivalent to reduction in melting temperature could be minimized during the glass production. Another important environmental benefit achieved by using carbonate free minerals is significant reduction (12%) of CO2 emissions during thermal decomposition in glass melting which could minimize greenhouse gas to the atmosphere at a great extent. Further, the addition of colemanite improved micro-hardness, elastic modulus and thermal properties of the pristine glass through polymerization of glass network structure. In contrast to the use of BPH as a source of more than 8 wt% Na2O deteriorated glass properties with the formation of non-bridging oxygens into the glass network.

Borax Pentahydrate and Disodium Pentaborate Decahydrate Are Candidates as Anti-leukemic Drug Components by Inducing Apoptosis and Changing Bax/Bcl-2 Ratio in HL-60 Cell Line

Acute myeloid leukemia (AML) is the most common form of acute leukemia and has the lowest 5-year survival rates. Current treatment strategies do not meet the expectations also. Therefore, there is a need to improve therapeutic approaches still. Boron, which is a natural trace element in human diet, is gaining attention with its important roles in cellular processes for the development of new anti-cancer drug candidates. For instance, bortezomib, a dipeptidyl boronic acid, has encouraging results in the treatment of multiple myeloma and mantle cell lymphoma. However, severe toxic effects and resistance development are the limitations to its application for AML treatment. Hence, the development of alternative boron-derived anti-AML agents is unmet need. Therefore, we aimed to evaluate anti-leukemic effect of two promising boron compounds, borax pentahydrate (BP) and disodium pentaborate decahydrate (DPD), and comparison of each other in terms of the capacity to trigger apoptosis on acute promyelocytic leukemia cells (HL-60). Cell viability was assessed by MTT assay. Apoptotic effects of the boron compounds on HL-60 cells were evaluated by annexin V/propidium iodide dyes and caspase 3/7 activity assay by flow cytometry. In addition, Bax/Bcl-2 and cleaved PARP levels were detected by western blotting. Although BP showed greater apoptosis-inducing capacity, we observed that both DPD (6mM) and BP (24mM) treatment showed anti-leukemic effect by triggering apoptotic pathway through increasing Bax/Bcl-2 ratio for the first time. Our study suggests that BP and DPD are the promising candidates for anti-AML drug development research, which may be confirmed by further wide-spectrum studies.

The use of borax pentahydrate of inorganic filler in medium density fiberboard production

The aim of the study was the use of the inorganic borax pentahydrate mineral in medium density fiberboard production instead of biomass fiber and to specify the performance which physical, mechanical, combustion of produced boards. Chips used in manufacture were subjected to cooking for 4,5 minutes in Asplund defibrator at the vapor pressure of 7,6 kg/cm2 pressure and 190 oC temperature. 1,6 % paraffin according to based on oven-dried wood fibers was added to cooked chips before the fiber processing in segments of defibrillator section. 1 % ammonium sulphate according to based on oven-dried wood fibers were added to fiber in the bowline. Borax pentahydrate was prepared in a separate tank in order to use the production of medium density fiberboard medium density fiberboard. Borax pentahydrate inorganic mineral was mixed with urea-formaldehyde resin. Urea-formaldehyde glue was prepared as three different solutions including the borax pentahydrate as 3 % (20 kg), 6 % (40 kg) and 9 % (60 kg) respectively. Borax pentahydrate mixed fibers were dried to 12 % moisture. Mat was formed before prepress. Daily multi-press was manufactured 188 °C temperature and 32 kg/cm² pressure and 270 second pressing time. Manufactured boards size were 2100x4900x18 (mm). According to this work result, 3 % and 6 % rate borax pentahydrate added medium density fiberboard boards were measured more good physical and mechanical test results compare to control boards. 9 % borax pentahydrate added medium density fiberboard boards were shown incredibly superior performance at fire resistance

Experimental investigation of effects of single and mixed alternative fuels (gasoline, CNG, LPG, acetone, naphthalene, and boron derivatives) on a commercial i-DSI engine

ABSTRACT A commercial i-DSI (Intelligent-Dual Sequential Ignition) engine is tested to investigate performance and emissions for single fuels and alternative fuels mixed into gasoline. The novelty of the study is the first time testing of the unconventional mixture of boron derivatives and quantification and comparison of real engine characteristics for 11 different fuels for the same commercial engine. Tested single fuels are gasoline (G100), CNG (CNG100), and LPG (LPG100). While the engine runs with gasoline, gaseous fuels are injected into the intake line at a mass rate of 10% CNG (CNG10) and 5% LPG (LPG5). The engine is also tested by adding 25–50% acetone (A25-A50) and 50% naphthalene (N50) into gasoline. Tests are also performed by mixing boron derivatives of borax-pentahydrate (BP), anhydrous-borax (AB), and boric-acid (BA) into gasoline. Tested fuels worsen engine performance compared to gasoline, except for brake specific fuel consumption (BSFC). There is a positive change in emissions for tested fuels compared to gasoline, except that NOx increases 4–5 times for CNG and LPG. One of the important findings is that, for boron-gasoline mixtures, the torque reduces by 4.0% for BP, 4.4% for AB, and 4.4% for BA. The volumetric efficiency decreases by 6.3% for BP, 7.3% for AB, and 8.5% for BA. The BSFC decreases 5.8% for BP, increases 0.4% for AB and decreases 15.2% for BA. Boron derivatives dissolved in gasoline diversely affect combustion and give some advantage in particular for BA and BP in terms of BSFC. In addition, boron-gasoline reduces the formation of HC and NOx.

Investigation of the therapy potential of borax pentahydrate in glioblastoma multiforme cell line

Recent studies with natural and synthetic boron compounds suggest that these compounds may be effective in the prevention and treatment of cancer. In this context, a synthetic boron compound, Borax pentahydrate (BPH), is aimed to be tested for cytotoxic effect on the glioblastoma multiforme (GBM) model U-87MG cell line representing fourth stage brain cancer in terms of induction of apoptosis and autophagy. Changes in apoptosis and autophagy rates of the research group treated with the specified IC50 dose of BPH were determined by fluorescence-based microcapillary cytometry kit (Muse® Annexin V & Cell Death and Muse® Autophagy LC3-antibody based kit). The data obtained were evaluated using GraphPad Prism 5 statistical program. The IC50 value of BPH in the U-87MG cell line was determined to be 2454μM for cytotoxicity. On the other hand, apoptosis rate was determined as increased 12.79 folds in the BPH treated group compared to the control group, while elevation of autophagy rate is determined as 1.2 folds. In the light of these data, while the cytotoxic effect of BPH on U-87MG cells, which is a model for GBM, is designated, it is understood that cell death pattern occurs through apoptosis instead of autophagy. In addition to these, it is thought that with the support of other new studies BPH may be an alternative agent that can be used in the treatment of GBM.

Effect of boron containing additives on asphalt performance and sustainability perspective

Recycling and sustainability concepts have recently come into prominence in pavement engineering as in other fields due to global warming. Pavement engineers conduct detailed studies on the production of asphalt concrete with recycled materials and apply their studies in work-site environment. This study aims to use boron wastes which formed in Eskisehir and surrounding provinces that hold nearly 70% of the world's boron reserves to the service of road construction industry. Furthermore, this research examines the performance characteristics and usability of asphalt concrete specimens prepared by adding respectively materials such as Crushed Boron Waste (CBW), Borax pentahydrate (BP) and Anhydrous Borax (BA) into the passed through 1.18 mm size aggregates. Asphalt concrete specimens are applied Marshall Design tests and creep tests. Test results prove that these three materials comply with the specifications. However, usage of CBW is considered to be more suitable in terms of long service life, financial, environmental and sustainability aspects. Boron waste additives will remove the environmental pollution caused by waste storages and provide significant profit in regard to sustainable life.

Effect of chicken feather and boron compounds as filler on mechanical and flame retardancy properties of polymer composite materials.

Sustainable utilisation of solid waste has been influenced by the increasing population of the world. Benefits of using solid waste based on natural fibre in polymer material are biodegradability and cost effectiveness. In poultry farms, chicken poultry, one of the slaughterhouse wastes is confronted with 30 106 kg of waste per year in Turkey. The evaluation of this waste, which is quite rich in keratin, is extremely important both for the solution of the waste problem and for maintaining a clean environment, bringing this valuable material to the economy. These fibres are stable, durable and biodegradable because they have a crystalline structure. However, this valuable waste will have a positive effect when used together with boron minerals, which both increase the mechanical properties, flame retardancy and biodegradation of composite material. In this study, it is the aim to manufacture superior polyester-based composite materials reinforced with three kinds of boron minerals, such as boron oxide, borax pentahydrate, borax decahydrate and fibres recycled from waste chicken feathers. The effect of different filling ratios of filling materials on the mechanical and physical properties of composite materials was examined. Flame retardancy properties of the composites with best mechanical results were investigated. After pouring by means of the pre-casting process, the water absorption and swelling thickness of final products, as well as density, bending strength, flexural modulus, limiting oxygen index, thermogravimetric analysis and scanning electron microscope analysis, was performed. Mixing prescriptions and conditions with the best properties were determined.

The Effect of Fiberboard Modification on Adhesion Strength to Polyvinyl Chloride (PVC) Sheets or Eastern Beech (Fagus orientalis L.) Veneers

The adhesion strength was evaluated for polyvinyl chloride (PVC) and Eastern beech (Fagus orientalis L.) veneers glued onto specially produced fiberboards using urea-formaldehyde (UF), polyvinyl acetate (PVAc), and polyurethane (PU) adhesives. Inorganic fillers including rock salt (NaCl), calcite (CaCO3), borax pentahydrate (Na2B44O7•5H2O), or talc (3MgO•4SiO2•H2O) were incorporated into the fiberboards at levels of 3%, 6%, and 9%. The adhesion strength of the samples was determined in accordance to Turkish Standard TS EN 311 (2005). Scanning electron microscopy (SEM) was employed to determine the structural morphology at the bonding interface of the veneers and the modified fiberboards. The results of this study indicated that veneer adhesion strength was reduced by the addition of inorganic fillers to the fiberboard. The highest adhesion strength was obtained with Eastern beech veneer that was glued using UF adhesive on the control samples without inorganic fillers. It was concluded that UF and PVAc adhesives are not suitable for bonding PVC veneers onto fiberboard surfaces.

Niobium carbide coatings produced on tool steels via thermo-reactive diffusion

Objective: In this work, niobium carbide (NbC) coatings were deposited on substrates of the tool steels AISI H13 and AISI D2 using thermo-reactive deposition/diffusion (TRD) in order to analyze their behavior against corrosion in a saline environment. Materials and methods: The niobium carbides were obtained using salt baths composed of borax pentahydrate, aluminum and ferroniobium. This mixture was heated at 1050 °C for 4 hours. The chemical composition was determined by X-ray fluorescence (XRF). The coatings were morphologically characterized using scanning electron microscopy (SEM), the crystal structure was analyzed using X-ray diffraction (XRD), and the electrochemical behavior was studied using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Results and discussion: The XRF analysis indicated that the coatings contained 87.476 wt% Nb and 51.943 wt% Nb for the D2-substrate and the H13-substrate, respectively. The SEM images revealed that the morphology of the surface of the coatings was homogeneous. The XRD analysis established that the coatings were polycrystalline, and the electrochemical tests established that the corrosion resistance increased slightly in the covered substrates with respect to the uncoated steels, with the best results being obtained in the layers of niobium carbide deposited on AISI D2 steel. Conclusions: The analysis of corrosion resistance revealed that the coatings prepared on D2 steel have a higher corrosion resistance because they have fewer surface imperfections, which causes the coating to exhibit a dielectric behavior.

Pine Cone and Boron Compounds Effect as Reinforcement on Mechanical and Flammability Properties of Polyester Composites

AbstractNatural fibers are known to be environmentally friendly, and they can be used as an alternative to glass and carbon fibers because of their low cost. Pine cone fibers are a good choice for use in composite manufacturing because they mainly consist of cellulose, hemicelluloses, and lignin macromolecules which provide a hydrophilic character.The potential pine cone forest reserve of Turkey is 54,000 ha. Boron compounds such as borax, boric acid. and zinc borate are generally used for their flame-retardant effect. In this study, three kinds of boron compounds, boron oxide, borax pentahydrate and borax decahydrate, were used to provide better mechanical properties and better incombustibility. The synergistic effects of both waste pine cone and boron compounds were sampled for the manufacture of polyester composites by using a casting process. The composites produced with different fiber contents were characterized by some mechanical properties (bending strength, flexural modulus, izod impact); physical analyses (water absorption, swelling thickness, open porosity, bulk density); flame retardancy (LOI); and TGA, SEM-EDS, and FT-IR analyses. According to mechanical test results, boron oxide showed better bending strength and flexural modulus compared to the other boron compounds. The LOI of composites with a boron compound was higher than the composites with only pine cone reinforcement.