Abstract:In this work, novel nanocomposite beads based on polyvinyl alcohol (PVA) coated polyacrylonitrile (PAN) with encapsulation of TiO 2 nanoparticles (PPT) were developed successfully via a novel green synthetic method and its methylene blue (MB) removal ability by adsorption was also investigated. As-prepared nanocomposite beads were characterized by different techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analys… Show more
“…PVA shows 3000-3700 cm −1 (O-H stretch), 2850-3000 cm −1 (CH 2 stretch) (C-H), 1736 cm −1 (C=O stretch), 1416 cm −1 (CH 2 bending), 1090-1150 cm −1 (C-O stretch) peaks. 50–54 Even with the highest rGO and GO ratio of 1%, these peaks were similar to PVA, so no visible difference could be achieved. This is because that rGO does not contain peaks and GO’s peaks overlap with peaks of PVA.Figure 3.FT-IR analysis of neat PVA, 1% GO/PVA and 1% rGO/PVA composites.…”
Petroleum-based polymers have a wide range of uses in the packaging industry, including films, food packaging, rigid containers, foamed containers, medical products, etc. This study focuses on improving the properties of polyvinyl alcohol (PVA) based material systems, one of the most popular water-soluble biopolymers, to reduce the waste of petroleum-based plastics, which are widely used. Polyvinyl alcohol (PVA) nanocomposite films containing low concentrations (0.05–1%) of graphene oxide (GO) and reduced graphene oxide (rGO) were produced via the solution casting method. When electrical properties of nanocomposite films were evaluated, the addition of 1 wt% GO and rGO resulted in a 36% and 45% decrease in the volumetric resistance of the films as well as a decrease in surface resistance of 24.5% and 34.9%, respectively. The maximum tensile strength of 1% GO and rGO-reinforced PVA nanocomposites was found to be ∼59 MPa and ∼68 MPa with an increase of 20% and 38% compared to neat PVA films, respectively. The average Young’s modulus of 1% GO and rGO-reinforced PVA nanocomposites also increased from 2561 MPa to 3515 MPa and 4219 MPa with an increase of 37% and 65%, respectively. As a result, the electrical conductivity, Young’s modulus, maximum tensile strength, thermal properties, and optical absorption of nanocomposite films increased by adding GO and rGO to PVA. The results show that the produced nanocomposite film may be a promising material for packaging applications.
“…PVA shows 3000-3700 cm −1 (O-H stretch), 2850-3000 cm −1 (CH 2 stretch) (C-H), 1736 cm −1 (C=O stretch), 1416 cm −1 (CH 2 bending), 1090-1150 cm −1 (C-O stretch) peaks. 50–54 Even with the highest rGO and GO ratio of 1%, these peaks were similar to PVA, so no visible difference could be achieved. This is because that rGO does not contain peaks and GO’s peaks overlap with peaks of PVA.Figure 3.FT-IR analysis of neat PVA, 1% GO/PVA and 1% rGO/PVA composites.…”
Petroleum-based polymers have a wide range of uses in the packaging industry, including films, food packaging, rigid containers, foamed containers, medical products, etc. This study focuses on improving the properties of polyvinyl alcohol (PVA) based material systems, one of the most popular water-soluble biopolymers, to reduce the waste of petroleum-based plastics, which are widely used. Polyvinyl alcohol (PVA) nanocomposite films containing low concentrations (0.05–1%) of graphene oxide (GO) and reduced graphene oxide (rGO) were produced via the solution casting method. When electrical properties of nanocomposite films were evaluated, the addition of 1 wt% GO and rGO resulted in a 36% and 45% decrease in the volumetric resistance of the films as well as a decrease in surface resistance of 24.5% and 34.9%, respectively. The maximum tensile strength of 1% GO and rGO-reinforced PVA nanocomposites was found to be ∼59 MPa and ∼68 MPa with an increase of 20% and 38% compared to neat PVA films, respectively. The average Young’s modulus of 1% GO and rGO-reinforced PVA nanocomposites also increased from 2561 MPa to 3515 MPa and 4219 MPa with an increase of 37% and 65%, respectively. As a result, the electrical conductivity, Young’s modulus, maximum tensile strength, thermal properties, and optical absorption of nanocomposite films increased by adding GO and rGO to PVA. The results show that the produced nanocomposite film may be a promising material for packaging applications.
“…The Fe-O stretching band originating from Fe 3 O 4 is observed at 420-500 cm −1 for the tetragonal sites and at 700 cm −1 for the octahedral sites. Furthermore, stretching bands characteristic of PVA were detected at 857 cm −1 (CC stretching) 19 , 1047-1147 cm −1 (C-O) 20 , 1350 cm −1 (=C-O-C), and 2966 cm −1 (CH 2 asymmetric stretching) 21 . The stretching bands characteristic of (C 6 H 7 O 6 Na) n were detected in the range 1473-1560 cm −1 (COO symmetric and asymmetric) 22 and at 1708 cm −1 (C=O) 23 .…”
New Fe 3 O 4 /polyvinyl alcohol (PVA)/sodium alginate (C 6 H 7 O 6 Na) n nanohybrid ferrogels for antibacterial applications were fabricated. The crystal and molecular structures along with optical and magnetic properties of the prepared samples were characterized. The antibacterial activity of the ferrogels against Bacillus subtilis and Escherichia coli was investigated using the agar dilution method. X-ray diffraction analysis showed that the Fe 3 O 4 /PVA comprised a PVA amorphous phase and a spinel-structured Fe 3 O 4 crystalline phase. The Fe 3 O 4 /PVA crystallite size was 7.5-9.9 nm and the scanning electron micrographs showed that the Fe 3 O 4 /PVA agglomerated. The ferrogels were superparamagnetic with saturation magnetizations from 14.8 × 10 −3 to 82.1 × 10 −3 emu/g. The absorption of the ferrogels showed a bathochromic effect, accompanied by an increase in the bandgap from 2.09 to 2.18 eV with increasing Fe 3 O 4 content in the ferrogels. The ferrogels demonstrated new potency as antibacterial agents against B. subtilis and E. coli, where their antibacterial performance increased with increasing Fe 3 O 4 content.
“…In the spectrum of the control, the sharp peak at 3640 cm –1 was assigned to Ca(OH) 2 , which formed during the cement hydration reaction [ 76 ]. However, this sharp peak did not appear in the other spectra, indicating that the cement hydration reaction was inhibited or that the CH was consumed [ 77 ]. This result is consistent with the absence of the diffraction peak at 18° from the XRD patterns.…”
During geothermal energy development, the bottom high-temperature fluid continuously exchanges heat with the upper low-temperature wellbore and the stratum during its rising process. Thermal insulation cement (TIC) can increase the outlet temperature, thus effectively reducing the heat loss of the geothermal fluid and improving energy efficiency. In this study, vitrified microbubbles (VMB) were screened out by conducting an orthogonal test of compressive strength (CS) and thermal conductivity (TC) on three inorganic thermal insulation materials (VMB, expanded perlite (EP), and fly-ash cenosphere (FAC)). Fumed silica (FS) was introduced into the cement with VMBs, as its significant decreasing effect on the TC. Moreover, a cement reinforcing agent (RA) and calcium hydroxide [CH] were added to further improve the CS of TIC at 90 °C. The fresh properties, CS, TC, hydration products, pore-size distribution, and the microstructure of the cement were investigated. As a result, a TIC with a TC of 0.1905 W/(m·K) and CS of 5.85 MPa was developed. The main conclusions are as follows: (1) Increasing the mass fraction of the thermal insulation material (TIM) is an effective method to reduce TC. (2) The CH content was reduced, but the C–S–H gel increased as FS content increased due to the pozzolanic reaction of the FS. (3) As the C–S–H gel is the main product of both the hydration and pozzolanic reactions, the matrix of the cement containing 60% FS and VMBs was mainly composed of gel. (4) The 10% RA improved the cement fluidity and increased the CS of TIC from 3.5 MPa to 5.85 MPa by promoting hydration.
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