Chemically functionalized SiO2 to improve mechanical properties of oil-impregnated monomer casting nylon

ABSTRACT: Toluene-2,4-diisocyanate and dodecanol were used to chemically functionalize nanosilica (TDID-SiO₂). Composites of TDID-SiO₂ and oil-impregnated monomer casting nylon (OMC nylon) were prepared by an in situ anionic ring-opening polymerization. The dispersion of the TDID-SiO₂ in oil was studied along with the mechanical and friction properties of the composites. The results show that the dispersion of the TDID-SiO₂ in oil was significantly enhanced. Specifically, some TDID-SiO₂ was wrapped in oil droplets, and the size of the oil droplets increased from 2.3 to 3.3 μm for 0–0.125 wt % of the TDID-SiO₂ nanoparticles, which was confirmed by scanning electron microscopy. The composites exhibited excellent mechanical properties when 0.10 wt % TDID-SiO₂ was integrated into OMC nylon. The tensile strength, elastic modulus, notched impact strength, flexural strength, and flexural modulus increased by 6.9%, 7.1%, 33.2%, 15%, and 77.5%, respectively, compared to OMC nylon without TDID-SiO₂ nanoparticles. The friction coefficient was effectively controlled and the abrasion quantity was reduced. Thermogravimetric analysis showed that the thermal decomposition temperature was also improved. The improved mechanical and frictional properties of TDID-SiO₂/OMC nylon composite will enhance its application in wear-resistant products in heavy industry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46994.     

Friction and wear behavior of C-based composites in situ reinforced with W2B5

The C-W₂B₅ composites with W₂B₅ content of 30 vol.% and 40 vol.% were fabricated by reaction hot pressing sintering. The mechanical properties and friction and wear behavior of the composites were investigated. For comparison, the friction and wear behavior of graphite was also studied. It was found that the presence of W₂B₅ grain resulted in notable improvements in mechanical properties and wear resistance of the composites compared to graphite in spite of a little higher friction coefficient. A graphite-rich mechanically mixed layer (MML) was formed on the worn surface of the composites, which facilitated the low friction coefficient. Fracture and removal of the MML depending on the fracture toughness of the composites and Hertzian stress levels were considered to be the main wear mechanism.     

Anionic nylon 6/TiO2 composite materials: Effects of TiO2 filler on the thermal and mechanical behavior of the composites

The nylon 6‐based composite materials containing untreated and surface‐treated TiO₂ particles with 3‐aminopropyltriethoxysilane (APTEOS), as coupling agent were prepared by in situ anionic polymerization of ε‐caprolactam in the presence TiO₂ as a filler using the rotational molding technique. The thermal behavior and mechanical properties of the neat nylon 6 and its composites were investigated using various techniques such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), a tensile and flexural test and impact strength. Experimental results revealed that both untreated and surface‐modified TiO₂ had distinct influence on the melting temperature (T_m), crystallization temperature (T_c), and degree of crystallinity (α_DSC), thermal stability, storage modulus (E′), and loss factor (tan δ), and mechanical properties of nylon 6 matrix. Dynamical mechanical analysis indicated that addition of TiO₂ particles into nylon 6 matrix increased both the storage modulus and the glass transition temperature. The corresponding values of nylon 6 composites with modified filler were higher than that of nylon 6 composite with untreated TiO₂ particles. Tensile and flexural characteristics of the nylon 6 composites were found to increase while the elongation at break and impact strength with increase in TiO₂ concentration relative to neat nylon 6. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

MECHANICAL AND THERMAL PROPERTIES OF NANO-AL2O3/NYLON 6 COMPOSITES

Nano-Al₂O₃-reinforced monomer casting nylon (NA/MCN) composites were prepared by using in situ polymerization. The average molecular weight of the matrix nylon was measured using gel permeation chromatography. The thermal-mechanical properties of the NA/MCN composites were characterized by thermo-dynamic mechanical analysis, and the results were compared with micro-Al₂O₃-reinforced nylon (MA/MCN) composites. A tensile property test was conducted to investigate the mechanical properties of neat nylon and composites. Experimental results showed that the average molecular weight of the matrix nylon filled with nano-alumina had little change and was higher than that with micro-alumina. The glass transition temperature (T_g) and storage moduli of NA/MCN composites were higher than that of neat nylon. During the experiment, it was also found that the tensile strength increased up to 52% when 3 wt.% of nano-Al₂O₃ particles were added. The thermal and tensile properties of NA/MCN composites were better than those of the MA/MCN composites when the same weight percentage of Al₂O₃ particles was used.     

Oil‐impregnated monomer casting nylon composites reinforced by graphene oxide and Lanthanum(III) chloride

Oil‐impregnated monomer casting (OMC) nylon composites reinforced by graphene oxide and Lanthanum(III) chloride (LaCl₃) were prepared by anionic ring‐opening polymerization in the presence of sodium hydroxide catalyst and toluene‐2, 4‐diisocyanate cocatalyst. The cross‐linked GO was formed by the coordination and electrostatic interactions between La³⁺ and the carboxyl on the edge of GO, which resulted in an obvious reinforcement for the OMC nylon composites. The effects of different rare earth contents on mechanical and tribological properties of the composites were carried out. The results showed that the composites exhibited excellent comprehensive properties when 0.01 wt% GO and 0.007 wt% LaCl₃ were incorporated in OMC nylon. The elastic modulus, flexural strength, flexural modulus, compressive strength, notched impact strength, and elongation‐at‐break for the OMC nylon/GO/LaCl₃ composites increased by 6.1, 9.9, 18.2, 7.2, 40.8, and 24.4%, respectively, and the tensile strength was slightly improved. In addition, the abrasion quantity was reduced. POLYM. ENG. SCI., 59:982–988, 2019. © 2019 Society of Plastics Engineers     

Hydrothermal mass production of MgBO2(OH) nanowhiskers and subsequent thermal conversion to Mg2B2O5 nanorods for biaxially oriented polypropylene resins reinforcement

Mass production of one-dimensional (1D) nanomaterials has emerged as one of the most significant challenges in powder technology. In this contribution, MgBO₂(OH) nanowhiskers were hydrothermally produced at a kilogram scale in a 150 L stainless steel autoclave at 200 °C for 12.0 h by using MgCl₂·6H₂O, H₃BO₃ and NaOH as the raw materials. The subsequent thermal conversion of the MgBO₂(OH) nanowhiskers at 700 °C for 6 h led to 3.75 kg of high crystallinity monoclinic Mg₂B₂O₅ nanorods, with a length of 0.47-1.3 µm, a diameter of 55-160 nm, and an aspect ratio of 3-15. After the nanorods have been surface modified with the silane coupling agent KH-550, the reinforcing and toughening effects of the Mg₂B₂O₅ nanorods on the biaxially oriented polypropylene resins (BOPP-D1) were evaluated. The filling of the Mg₂B₂O₅ nanorods into the resins resulted in the increase in the tensile strength, the impact strength, and the melt flow index of the BOPP-D1 composites. The appropriate ratio of coupling agent to fillers (Mg₂B₂O₅ nanorods) and the ratio of fillers to resins were determined within the range of 0.6-1.2 wt.% and 8-15 wt.%, respectively. The optimal ratio of fillers to resins was ca. 10 wt.%. The present mass production of MgBO₂(OH) nanowhiskers and Mg₂B₂O₅ nanorods is believed to be helpful for enlarging and propelling the applications of the 1D magnesium borate nanostructures in the near future.     

The synthesis and microwave dielectric properties of Mg3B2O6 and Mg2B2O5 ceramics

Single-phase Mg₃B₂O₆ and Mg₂B₂O₅ ceramics were synthesized and then structurally and dielectrically characterized. The highest Qxf value of 230,900 GHz was obtained for a Mg₃B₂O₆ ceramic with a density of 97% and 1000-μm grains. Considerably lower Qxf values (10,000–32,000 GHz) were determined for the Mg₂B₂O₅ ceramic. Mg₃B₂O₆ and Mg₂B₂O₅ exhibited permittivities (?) of 7.2 and 6.2–7.0, respectively. Both ceramics showed negative temperature coefficients of resonant frequency (τ_f) of ?18 to ?45 ppm/°C.     

Mechanical and thermal behavior of polycarbonate composites reinforced with aluminum borate whiskers

Inorganic aluminum borate (Al₁₈B₄O₃₃) whisker was employed in this study to reinforce polycarbonate (PC). The composites were prepared in a single-screw extruder, followed by injection molding. The whiskers were pretreated with tetrabutyl orthotitanate prior to compounding. The tensile, dynamic mechanical, impact, and thermal properties of the composites were studied. Tensile results showed that the modulus of PC–Al₁₈B₄O₃₃ composites increased markedly with increasing whisker content. However, the tensile stress of the composite decreased slightly with the addition of 5 wt % whisker; thereafter, it increased slowly with increasing whisker content. Differential thermal analysis and thermogravimetric measurements showed that the glass transition temperature (T_g) and 5% weight loss temperature (T_−5%) of the composite shift rapidly to lower temperature regimes with the addition of Al₁₈B₄O₃₃ whiskers up to 10 wt %. Thereafter, the T_g and T_−5% of PC–Al₁₈B₄O₃₃ composites tended to decrease slowly with increasing whisker content. The mechanical and thermal properties of PC–Al₁₈B₄O₃₃ composites were compared with those of PC–potassium titanate (K₂Ti₆O₁₃) whisker composites. The reinforcing effect of Al₁₈B₄O₃₃ and K₂Ti₆O₁₃ whiskers on PC was discussed and contrasted. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2247–2253, 1999     

Friction and wear characteristics of ceramic particle filled polytetrafluoroethylene composites under oil-lubricated conditions

Five kinds of polytetrafluoroethylene (PTFE)-based composites were prepared: PTFE, PTFE + 30 vol % SiC, PTFE + 30 vol % Si₃N₄, PTFE + 30 vol % BN, and PTFE + 30 vol % B₂O₃. The friction and wear properties of these ceramic particle filled PTFE composites sliding against GCr15 bearing steel under both dry and liquid paraffin lubricated conditions were studied by using an MHK-500 ring-block wear tester. The worn surfaces and the transfer films formed on the surface of the GCr15 bearing steel of these PTFE composites were investigated by using a scanning electron microscope (SEM)and an optical microscope, respectively. The experimental results show that the ceramic particles of SiC, Si₃N₄, BN, and B₂O₃ can greatly reduce the wear of the PTFE composites; the wear-reducing action of Si₃N₄ is the most effective, that of SiC is the next most effective, then the BN, and that of B₂O₃ is the worst. We found that B₂O₃ reduces the friction coefficient of the PTFE composite but SiC, Si₃N₄, and BN increase the friction coefficients of the PTFE composites. However, the friction and wear properties of the ceramic particle filled PTFE composites can be greatly improved by lubrication with liquid paraffin, and the friction coefficients of the PTFE composites can be decreased by 1 order of magnitude. Under lubrication of liquid paraffin the friction coefficients of these ceramic particle filled PTFE composites decrease with an increase of load, but the wear of the PTFE composites increases with a load increase. The variations of the friction coefficients with load for these ceramic particle filled PTFE composites under lubrication of liquid paraffin can be properly described by the relationship between the friction coefficient (μ) and the simplified Sommerfeld variable N/P as given here. The investigations of the frictional surfaces show that the ceramic particles SiC, Si₃N₄, BN, and B₂O₃ enhance the adhesion of the transfer films of the PTFE composites to the surface of GCr15 bearing steel, so they greatly reduce the wear of the PTFE composites. However, the transfer of the PTFE composites onto the surface of the GCr15 bearing steel can be greatly reduced by lubrication with liquid paraffin, but the transfer still takes place. Meanwhile, the interactions between the liquid paraffin and the PTFE composites, especially the absorption of liquid paraffin into the surface layers of the PTFE composites, create some cracks on the worn surfaces of the ceramic particle filled PTFE composites; the creation and development of these cracks reduces the load-supporting capacity of the PTFE composites. This leads to the deterioration of the friction and wear properties of the PTFE composites under higher loads in liquid paraffin lubrication. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2611–2619, 1999     

Effect of in situ surface‐modified nano‐SiO2 on the thermal and mechanical properties and crystallization behavior of nylon 1010

Nylon 1010 composites filled with two types of surface‐modified SiO₂ nanoparticles (RNS and DNS) were prepared by melt blending. The mechanical properties of the composites were evaluated. The influences of the surface‐modified nano‐SiO₂ on the thermal stability, crystallization behavior, and microstructure of nylon 1010 were investigated by thermogravimetric analysis, differential scanning calorimetry (DSC), X‐ray diffraction, and transmission electron microscopy. And the interfacial interactions between the fillers and polymer matrix were examined using a Fourier transformation infrared spectrometer. It was found that the addition of the surface‐modified nano‐SiO₂ had distinct influences on the thermal stability, mechanical properties, and crystallization behavior of nylon 1010. RNS and DNS as the fillers had different effects on the mechanical properties of nylon 1010. The composites filled with RNS at a mass fraction of 1–5% showed increased break elongation, Young's modulus, and impact strength but almost unchanged or even slightly lowered tensile strength than the unfilled matrix. The DNS‐filled nylon 1010 composites had obviously decreased tensile strength, whereas the incorporation of DNS also contributed to the increase in the Young's modulus of nylon 1010, but less effective than RNS. Moreover, the nylon 1010 composites had better thermal stability than the neat polymer matrix, and the composites filled with RNS were more thermally stable than those filled with DNS. The difference in the crystallinity of neat nylon 1010 and its composites filled with RNS and DNS was subtle, although the surface‐modified nano‐SiO₂ could induce or/and stabilize the γ‐crystalline formation of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparative study of B4C,Mg2B2O5, and ZrB2 powder additions on the mechanical properties,oxidation, and slag corrosion resistance of MgO–C refractories

Boron-containing additives are used to improve the oxidation resistance of carbon-containing refractories; however, their effects on the mechanical properties and slag corrosion resistance of the refractories have rarely been studied. In this work, B₄C, Mg₂B₂O₅, and ZrB₂ powders were incorporated into low-carbon MgO–C refractories to study their effects on the mechanical properties, oxidation resistance, and slag corrosion resistance of the refractories. The relationships between these properties and the microstructure and phase evolution were also studied. The results show that the flexural strengths of the MgO–C refractories at high temperatures are closely related to the apparent porosity and formation of an Mg₃B₂O₆ phase. The oxidation resistances are greatly improved after the introduction of boron-containing additives into the MgO–C refractories in terms of both thermodynamical aspects and the filling of voids and pores. The most effective antioxidant is B₄C, followed by the ZrB₂ and Mg₂B₂O₅ powders. The mechanisms through which the vanadium-containing slag attacks the MgO–C refractories mainly include the dissolution of magnesia to form melting phases, penetration through pores, and redox reaction with carbon.     

Effect of magnesium source on the fabrication of kotoite Mg3B2O6 ceramic

The effect of magnesium source on the fabrication of kotoite, Mg₃B₂O₆, ceramic has been investigated by high temperature solid‐state reaction route based on the calcination of different magnesium sources, containing magnesium oxide, magnesium carbonate, magnesium sulfate, and magnesium nitrate with boric acid. The X‐ray powder diffraction results showed that single‐phase kotoite, Mg₃B₂O₆, was synthesized using MgNO₃.6H₂O and 5 wt.% excess of H₃BO₃ powders as starting materials at 900°C for 48 hours. Mg₃B₂O₆ obtained, is well crystallized, in orhorhombic crystal structure with lattice parameters of a = 5.399(9), b = 8.424(6), and c = 4.506(5) Å. Jana2006 refinement of this product shows excellent fit of the experimental data with software data, GOF= 1.33. The crystallite size of the product was calculated as 40.50 nm using Debye‐Scherrer's equation. The existence of BO₃ triangles were detected by FTIR measurements of Mg₃B₂O₆. The thermal properties were studied in the temperature range of 20°C to 1400°C by TG/DTA. The results showed that thermal stability of Mg₃B₂O₆ is detected about 1380°C. Scanning electron microscopy was employed for observation of microstructure. The microstucture of obtained ceramic samples strongly depended on the magnesium source on the fabrication of Mg₃B₂O₆ ceramic.     

Three-phase borate solid solution with low sintering temperature,high-quality factor,and low dielectric constant

The sintering and microwave dielectric properties of a ceramic material based on the mixing of Mg₃B₂O₆ and Zn₃B₂O₆ have been widely studied using first-principles calculations and experimental solid-state reactions. Characterization methods include the Network Analyzer, X-ray, Raman diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and differential-thermal and thermo-mechanical analyzer. The increasing amount of Mg²⁺ results in the appearance of Mg₂B₂O₅ and ZnO, and the mutual substitution (Mg²⁺ and Zn²⁺) phenomenon has emerged in Zn₃B₂O₆ and Mg₂B₂O₅. The mechanisms have been explained with the help of DFT calculations. The bond parameters and electron distributions of the ZnO₄ tetrahedron and MgO₆ octahedron have been modified due to substitution. The sintering, substitution, and phase formation properties have been analyzed quantitatively through the energy parameters. The best dielectric properties were obtained for x = 0.20 sintered at 950°C, ε_r = 6.47, Q × f = 89 600 GHz (15.2 GHz), τ_f = −48.6 ppm/°C, relative density = 96.7%. The mixing of Zn₃B₂O₆ and Mg₃B₂O₆ ceramics is a feasible method to obtain a ceramic with low sintering temperature and excellent dielectric properties.     

The crystallization,thermal and mechanical properties of nano‐Sb2O3 filled poly(butylene terephthalate)

Nano‐Sb₂O₃ particles were modified by a combination modifier of cetyltrimethyl ammonium bromide (CTAB) and KH‐560 via the mechanochemical method based on high‐energy ball milling. Then, the testing specimens of the nano‐Sb₂O₃/PBT composites of differing compositions were prepared by melting blending technology. The crystallization, thermal, and mechanical properties of composites were characterized by X‐ray diffraction, differential scanning calorimetry, thermogravimetric analyzer, and mechanical performance test. The tensile and impact fracture surfaces of composites were determined by scanning electron microscopy. Besides, the influence of the Sb₂O₃ nanoparticles surface modification on crystallinity, mechanical properties of the composites, and the interfacial adhesion between nano‐Sb₂O₃ and PBT was systematically investigated. The results indicate that the main crystalline characteristics of PBT matrix remain unchanged in the nanocomposites. However, the addition of nano‐Sb₂O₃ particles plays a heterogeneous nucleation and can effectively improve the crystallization of PBT matrix. In addition, the compound modification of the nano‐Sb₂O₃ can effectively enhance mechanical properties of the composites and interfacial interaction between nano‐Sb₂O₃ and PBT. The enhanced fracture properties in the nanocomposites were caused by the assisted void formation at the edge of the nano‐Sb₂O₃ particle. When the nano‐Sb₂O₃ mass fraction is 3%, the composites show excellent comprehensive performance. The interfacial adhesion parameter B and the half‐debonding angle θ of composites were assessed to quantitatively characterize the interfacial adhesion strength between nano‐Sb₂O₃ and PBT. Finally, the reinforcement and toughening mechanisms were described. J. VINYL ADDIT. TECHNOL., 26:268–281, 2020. © 2019 Society of Plastics Engineers     

Improved Mg3B2O6: Its’ variation in crystallite size,vibration mode,band structure,sintering, and dielectric properties

Cobalt-substituted Mg₃B₂O₆ ceramic has been explored through the solid-state reaction method and the density functional theory. The advantage of cobalt substitution is that it increases the crystallite size, enhances the order degree, modifies the band structure properties, densifies the microstructure, lowers the intrinsic densification temperature and improves the dielectric properties of Mg₃B₂O₆ ceramic without sintering aids. The sintering and dielectric performance of Mg₃B₂O₆ ceramic have been ameliorated, and two phases are formed (Mg₃B₂O₆ and Mg₂B₂O₅). The top values for the substituted sample are 97.1% for relative density, 6.83 for dielectric constant, 81,200 GHz (15 GHz) for quality factor and −56.1 ppm/°C for τ_f when 5% cobalt (mole ratio) is substituted. The optimised densification temperature is 1200 °C.     

Low-loss and temperature stable (1-x)Ba3P2O8-xMg2B2O5 composite ceramics with low sintering temperature

In this study, the Ba₃P₂O₈ and Mg₂B₂O₅ were fabricated by the solid-state reaction method separately, and the (1-x)Ba₃P₂O₈-xMg₂B₂O₅ (x = 0.2–0.4) low-temperature co-fired ceramic (LTCC) materials were obtained in the sintering temperature range of 880–960 °C. The phase compositions, microstructures, elemental compositions, and microwave dielectric properties of the (1-x)Ba₃P₂O₈-xMg₂B₂O₅ composite ceramics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and TE_01δ mode dielectric resonator method, respectively. The results revealed that the Mg₂B₂O₅ phase and Ba₃P₂O₈ phase could coexist well in the (1-x)Ba₃P₂O₈-xMg₂B₂O₅ composite ceramics without formation of any new phases. The abnormal grain growth of Ba₃P₂O₈ grains was inhibited by the addition of Mg₂B₂O₅. In addition, through composition of Ba₃P₂O₈ and Mg₂B₂O₅, the temperature coefficient of resonant frequency (τ_f) and quality factor (Q×f) were effectively optimized, and the sintering temperature was reduced to 880–960 °C. The optimal performance of 0.8Ba₃P₂O₈-0.2Mg₂B₂O₅ composite ceramic was achieved at a sintering temperature of 920 °C, τ_{f =} ?1.9 ppm/°C, Q×f = 61,250 GHz, and a low permittivity ε_r = 10.7. The chemical compatibility test demonstrated that the composite ceramic could coexist well with silver, which indicated that the 0.8Ba₃P₂O₈-0.2Mg₂B₂O₅ composite ceramic is a candidate LTCC material with wide application prospects.     

Partial cation substitution of tunable blue-cyan-emitting Ba2B2O5:Ce3+ for near-UV white LEDs

In this study, Sr²⁺, Ca²⁺, Zn²⁺, and Mg²⁺ ions act to tune the emission band to the blue-cyan region in Ba_xSr_yB₂O₅:Ce³⁺ (BSBO), Ba_xCa_zB₂O₅:Ce³⁺ (BCBO), Ba_xZn_uB₂O₅:Ce³⁺ (BZBO), and Ba_xMg_vB₂O₅:Ce³⁺ (BMBO) phosphors. A red shift occurs with the increase of Sr²⁺, Ca²⁺, Zn²⁺, and Mg²⁺ concentration, and a blue shift occurs when the concentrations of Sr²⁺, Ca²⁺, Zn²⁺, and Mg²⁺ exceed the critical value. The emission color can be tuned from deep blue (0.15, 0.12) to cyan (0.16, 0.27) upon 365 nm UV lamp excitation due to the crystal field splitting and centroid shifts. The excitation band shift to long wavelength by introducing ions, so that the synthesized phosphor can be better matched with the n-UV chip. The emission intensity slowly decreases with the temperature increasing. Therefore, the BMBO:Ce³⁺, BZBO:Ce³⁺, BCBO:Ce³⁺, and BSBO:Ce³⁺ phosphors with relatively good thermal stability were synthesized, which could have potential applications in the n-UV white LEDs.     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

Synthesis and characterization of single-phase magnesium borate nanorod via solution reaction cum sintering process

Magnesium borates (MB) nanorods are widely used as reinforcing materials due to high mechanical strength and resilience to heat and corrosion. However, difficulties in synthesis of single-phase MB continue to reduce the mechanical properties of composites. Herein, a single-phase Magnesium borate (Mg₂B₂O₅) in the form of nanorod has been synthesized using an optimized molar ratio of magnesia (MgO) and boric acid (H₃BO₃) by combining solution reaction and sintering process. Phase and microstructural changes of as synthesized magnesium borate (MB) crystals during the reaction sintering process in between 700 °C and 1200 °C has been closely examined with the help of various characterization techniques. Phases of magnesium borate starts appearing on thermal treatment above 700 °C. Phase transformation of magnesium borate from monoclinic to orthorhombic followed by triclinic was also observed during the thermal treatment. The optimum temperature to obtain pure triclinic Mg₂B₂O₅ phase was found to be in between 1100°C and 1200 °C.     

Extraction of titanium dioxide (TiO2) from ilmenite and titaniferous slag

Solutions of ilmenite (FeTiO₃) and a titaniferous slag, in fused Li₂O. 2B₂O₃ and Li₂O. 4B₂O₃, yield on cooling compounds tentatively identified as LiFe₂.₅Ti₃O₉ and Li₂Fe₃Ti₂.₅O₉ respectively. Both compounds are orthorhombic, and have the pseudobrookite structure. The ilmenite solutions yield, in addition, rutile (TiO₂). The yield of rutile increases from about 1 to 24% (w/w) of the products, when the solvent is changed from Li₂O. 2B₂O₃ to Li₂O. 4B₂O₃. Substitution of K₂O. 4B₂O₃ for the latter solvent decreases the yield of rutile to c. 10%. The yield of rutile is approximately in inverse proportion to the Lux—Flood basicity of the borate solvent.