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A new, sustainable polypropylene terephthalate (PPT) coating was synthesized from recycled polyethylene terephthalate (PET) and applied onto a hydraulic concrete substrate to improve its durability. For the first step, PET bottle wastes were ground and depolymerized by glycolysis using propylene glycol (PG) in a vessel-type reactor (20–180 °C) to synthesize bis(2-hydroxypropyl)-terephthalate (BHPT), which was applied as a coating to one to three layers of hydraulic concrete substrate using the brushing technique and polymerized (150 °C for 15 h) to obtain PPT. PET, BHPT, and PPT were characterized by FT-IR, PET, and PPT using TGA, and the PPT coatings by SEM (thickness), ASTM-D3359-17 (adhesion), and water contact angle (wettability). The durability of hydraulic concrete coated with PPT was studied using resist chloride ion penetration (ASTM-C1202-17), carbonation depth at 28 days (RILEM-CPC-18), and the absorption water ratio (ASTM-C1585-20). The results demonstrated that the BHPT and PPT were synthetized (FT-IR), and PPT had a similar thermal behavior to PET (TGA); the PPT coatings had good adhesion to the substrate, with thicknesses of micrometric units. PPT coatings presented hydrophilic hydrophilic behavior like PET coatings, and the durability of hydraulic concrete coated with PPT (2–3 layers) improved (migration of chloride ions decreased, carbonation depth was negligible, and the absorption water ratio decreased). [ABSTRACT FROM AUTHOR]

Tungsten trioxide (WO3) is a versatile n-type semiconductor with outstanding chromogenic properties highly used to fabricate sensors and electrochromic devices. We present a comprehensive experimental study related to piezoresponse with piezoelectric coefficient d33 = 35 pmV−1 on WO3 thin films ~200 nm deposited using RF-sputtering onto alumina (Al2O3) substrate with post-deposit annealing treatment of 400 °C in a 3% H2/N2-forming gas environment. X-ray diffraction (XRD) confirms a mixture of orthorhombic and tetragonal phases of WO3 with domains with different polarization orientations and hysteresis behavior as observed by piezoresponse force microscopy (PFM). Furthermore, using atom probe tomography (APT), the microstructure reveals the formation of N2-filled nanovoids that acts as strain centers producing a local deformation of the WO3 lattice into a non-centrosymmetric structure, which is related to piezoresponse observations. [ABSTRACT FROM AUTHOR]

Hybrid coatings of SiO2 and recycled unsaturated polyester resin (R-UPR) from recycled polyethylene-terephthalate (PET) were prepared by the sol-gel process on glass substrates. First, SiO2 was synthesized by the sol-gel process using a tetraethyl orthosilicate (TEOS) solution. Next, bis(2-hydroxypropyl-terephthalate) (BHPT) was synthesized from mechanical and chemical recycling (glycolysis) of post-consumer PET bottles in propylene glycol (PG) using ZnA as catalyst, in a Vessel-type reactor (20–200 °C); maleic anhydride (MA) was added and, following the same procedure, the unsaturated polyester (UP) was synthetized, which was cooled to room temperature. Next, styrene (St) and benzoyl-peroxide (PBO)-initiator were added to obtain R–UPR. TEOS (T) and three hybrid solutions were synthesized, with molar ratios of 0:1:0 (T), 1:2:0.25 (H1), 1:1:0.25 (H2), and 1:0:0.25 (H3) for R–UPR:TEOS:3-trimethoxy-(silyl)-propyl-methacrylate (TMSPM), respectively, with which TC, HC1, HC2, and HC3 coatings were elaborated using the immersion technique and polymerized (120 °C for 24 h). The solutions were characterized by FT–IR and TGA, and the coatings by SEM, nanoindentation, AFM, adhesion, and contact angle. The results showed that SiO2 enhanced mechanical (hardness and Young's modulus) and thermal properties of the R-UPR. The coatings adhered perfectly to the substrate, with thicknesses of micrometer units and a flat surface; in addition, hydrophilicity decreased as SiO2 decreased. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (nZVI) has proved to be an effective tool in applied environmental nanotechnology, where the decreased particle diameter provides a drastic change in the properties and efficiency of nanomaterials used in water purification. However, the agglomeration and colloidal instability represent a problematic and a remarkable reduction in nZVI reactivity. In view of that, this study reports a simple and cost-effective new strategy for ultra-small (< 7.5%) distributed functionalized nZVI-EG (1-9 nm), with high colloidal stability and reduction capacity. These were obtained without inert conditions, using a simple, economical synthesis methodology employing two stabilization mechanisms based on the use of non-aqueous solvent (methanol) and ethylene glycol (EG) as a stabilizer. The information from UV-Vis absorption spectroscopy and Fourier transform infrared spectroscopy suggests iron ion coordination by interaction with methanol molecules. Subsequently, after nZVI formation, particle-surface modification occurs by the addition of the EG. Size distribution analysis shows an average diameter of 4.23 nm and the predominance (> 90%) of particles with sizes < 6.10 nm. Evaluation of the stability of functionalized nZVI by sedimentation test and a dynamic light-scattering technique, demonstrated very high colloidal stability. The ultra-small particles displayed a rapid and high nitrate removal capacity from water. [ABSTRACT FROM AUTHOR]

Pure and Mn‐doped barium titanate nanofibers were synthesized by the electrospinning method. The morphology, microstructure and crystal structure of as‐spun and annealed composite nanofibers were characterized by scanning electron microscopy and transmission electron microscopy. After annealing at 850°C, we obtain nanofibers a few μm long, formed by nanoparticles of irregular shape with sizes around 100 nm. X‐ray diffraction and Raman spectroscopy show that a partial phase transition from tetragonal to hexagonal takes place for BaTi0.90Mn0.10O3. Vibrational phonon modes were calculated for BaTiO3 within the density functional theory (DFT) framework. Ferroelectricity has been probed on pure and Mn‐doped BaTiO3 nanofibers, by means of piezoresponse force microscopy in an atomic force microscope, confirming the polar domain switching behavior of the fibers. The measured piezoelectric coefficient d33 were 31 and 22 pm/V for BaTiO3 and BaTi0.90Mn0.10O3. Magnetic properties of the samples were probed in a superconducting quantum interference device. Diamagnetic and paramagnetic behaviors were found in pure and Mn‐doped samples, respectively. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to identify the link between alloy microstructures and the nanomechanical properties of different orthodontic archwires containing nickel-titanium (NiTi) by sensing sliced areas. Previous studies have focused on analyzing and contrasting physical properties such as microhardness, elasticity modulus, and resistance; therefore, the trend is to consider microstructural characteristics in detail., Methods: Thirty archwire samples from 3 different commercial brands, American Orthodontics (AO), 3M Unitek (3M), and Borgatta, were analyzed through scanning electron microscopy and energy-dispersive x-ray spectroscopy, transmission electron microscopy, atomic force microscopy, Berkovich nanoindentation, and microtensile microscopy to determine their chemical-crystallographic characteristics and nanomechanical and bending characteristics., Results: The identified formulations of AO and 3M had averages of 20 wt%, for Ni and 15.4 wt% for Ti, with lower concentrations for Borgatta. Alloys of Ni and Ti were distributed in different concentrates in the matrix of the archwires. The nanomechanical properties showed high values of the elastic modulus (82.8 ± 3.6 GPa) and hardness (6.4 ± 1.2 GPa) and a minor deformation degree of 0.38% for the AO wires, although the bending strength exhibited the highest values for 3M. No corrosion was observed with a prolonged hydrolytic attack on the surface of any of the wires (0.0-0.5 National Bureau of Standards units)., Conclusions: The highest nanomechanical properties and bending characteristics were observed for wires with higher NiTi precipitate contents, which were distributed differently in the alloy overall in the matrix. The nanoindentations sensed in different areas evidenced different mechanical properties for NiTi depending on its concentrations of Ti and enucleations., (Copyright © 2024 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)