Influence Of Polyvinylpyrrolidone Research Articles

Micro and nanostructured carbon-phenolic ablators modified by PVP addition

Carbon-phenolic ablators can efficiently protect space vehicles from the extreme temperatures typical of the reentry phase in a planet’s atmosphere. Their performances are attributed to the low thermal conductivity and to the decomposition of the phenolic resin. These phenomena are strongly influenced by the materials microstructure. In the present work, standard and polyvinylpyrrolidone (PVP)-modified carbon-phenolic ablators were manufactured and characterized: the influence of PVP on the final microstructure and chemistry of the ablators was studied through SEM-EDS, X-ray Microscopy (XRM) analysis and FTIR technique; the mechanical properties were evaluated through compression tests on virgin and charred samples while ablative performance of the ablators were evaluated with an oxyacetylene flame exposure test. Weak bonds between phenolic resin chains and PVP were observed. The microstructure of the ablators, both before and after the exposure to the oxyacetylene flame, is strongly influenced by the PVP addition, furthermore the addition of 10 and 20 %wt of PVP can guarantee a reduction of about 30 % of the back temperature during the oxyacetylene flame test with respect to the standard carbon-phenolic ablator. Compression tests on the manufactured ablators enlighten also an improvement in the mechanical properties for PVP-enriched ablators, in particular considering their charred state.

Influence of PVP on the properties of solvothermally synthesized famatinite nanoparticles: Structural, morphological and optical insights

Famatinite (Cu3SbS4) nanoparticles were synthesized through a solvothermal approach using various polyvinylpyrrolidone (PVP) ratios as a capping agent with a binary solvent of ethylene glycol and water in equal parts. Incremental additions of PVP, ranging from 0 to 1.5 g, exerted significant influence on the material's characteristics. Through comprehensive analysis involving X-ray diffraction, Raman spectroscopy, Scanning electron microscopy (SEM) with Energy dispersive spectrometer (EDS), and UV diffuse reflectance spectroscopy, critical insights were obtained. XRD analysis confirmed the tetragonal crystal structure and revealed reduced crystallite sizes due to the incorporation of PVP. Raman spectroscopy validated the presence of pure famatinite phase with 0.5 g and 1.0 g PVP. SEM analysis uniformly depicted a spherical morphology in all samples, emphasizing PVP's role in mitigating nanoparticle agglomeration. UV diffuse reflectance spectroscopy disclosed direct bandgaps falling within the 0.88 – 0.97 eV range. The collective findings highlighted the substantial impact of PVP in the binary solvent on the structural, morphological, and optical properties of Cu3SbS4 nanoparticles. These results underscore the potential application of these tailored nanoparticles as promising candidates for advanced photovoltaic absorber materials.

Capping Agents Enable Well-Dispersed and Colloidally Stable Metallic Magnesium Nanoparticles.

Mg nanoparticles are an emerging plasmonic material due to Mg's abundance and ability to sustain size- and shape-dependent localized surface plasmon resonances across a broad range of wavelengths from the ultraviolet to the near infrared. However, Mg nanoparticles are colloidally unstable due to their tendency to aggregate and sediment. Nanoparticle aggregation can be inhibited by the addition of capping agents that impart surface charges or steric repulsion. Here, we report that the common capping agents poly(vinyl) pyrrolidone (PVP), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS) interact differently and have varied effects on the aggregation and colloidal stability of Mg nanoparticles. Nanoparticles synthesized in the presence of PVP showed improvements in colloidal stability and reduced aggregation, as observed by electron microscopy and optical spectroscopy. The binding of PVP was confirmed through infrared and X-ray photoelectron spectroscopy. The influence of PVP on the reduction of di-n-butyl magnesium was evaluated through analysis of particle size distribution and Mg yield as a function of reaction time, reducing agent, and temperature. Furthermore, the presence of PVP drastically changes the growth pattern of metallic Mg structures obtained from the reduction of the Grignard reagents butylmagnesium chloride and phenylmagnesium chloride by lithium naphthalenide: large polycrystalline aggregates and well-separated faceted nanoparticles grow without and with PVP, respectively. This study provides new synthetic routes that generate colloidally stable and well-dispersed Mg nanoparticles for plasmonic and other applications.

The Influence of Polyvinylpyrrolidone as a Polymer Modifier on the Morphology and Properties of Copolyamide

The Influence of Polyvinylpyrrolidone as a Polymer Modifier on the Morphology and Properties of Copolyamide

One-Pot Synthesis of Pt High Index Facets Catalysts for Electrocatalytic Oxidation of Ethanol.

Direct ethanol fuel cell (DEFC) has attracted wide attention due to its wide range of fuel sources, cleanliness, and high efficiency. However, the problems of low catalytic efficiency and poor catalyst stability still exist in DEFC catalysts, which restrict its rapid development. With chloroplatinic acid (H2PtCl6·6H2O) as the precursor, Polyvinylpyrrolidone (PVP) plays the role of surfactant, stabilizer, and reducing agent in the experiment. Glycine is the surface control agent and co-reducing agent. Pt high-index facets nanocatalyst was prepared with the one-pot hydrothermal method by adjusting the amount of PVP and glycine. X-Ray Diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM) were used to characterize the micro-structure of the nanocatalyst, and the influence of PVP and glycine on the synthesis of high-index facets catalyst was studied. The electrocatalytic performance of the catalyst was tested with an electrochemical workstation, and it was found that the performance of the prepared catalyst was better than that of the commercial catalyst. When the mass ratio of PVP and Pt was 50:1 and the molar ratio of glycine and Pt was 24:1, Pt nanocatalysts with {310}, {520} and {830} high exponential facets were prepared. The electrochemical test results showed that the peak current density of ethanol oxidation was 2.194 m2/g, and the steady-state current density was 0.241 mA/cm2, which was 5.7 times higher than that of commercial catalyst. The results of this paper show that due to the defects such as steps and kinks on the surface of the high-index facets, the active sites are increased, thus showing excellent electrocatalytic performance. This study provides a theoretical basis for the development and commercial application of high index facets nanocatalysts.

Influence of polyvinylpyrrolidone as stabilizing agent on Pt nanoparticles in Pt/H-BEA catalyzed hydroconversion of n-hexadecane

Colloidal Pt particles prepared using polyvinylpyrrolidone (PVP) as a capping agent were loaded on acidic Beta zeolite, with the aim of obtaining bifunctional catalysts with controllable dispersion for the hydroconversion of n-hexadecane (n-C16). Among the different approaches to remove PVP, reduction was the most effective whilst maintaining the initial Pt particle size after deposition on the zeolite. The presence of small amounts of nitrogen- and carbon-containing products from PVP decomposition affected the acidity stronger than the Pt metal function. Therefore, it was not possible to establish the effect of Pt particle size on the performance of the Pt/Beta zeolites in n-C16 hydroconversion and the performance trends were dominated by the acidity differences. Small Pt particles on zeolite obtained by using high PVP/Pt ratios during the colloidal synthesis step presented lower Brønsted acidity than catalysts containing larger Pt particles. The resulting variations in Pt/H+ ratios led to a transition of observed ideal cracking behavior for weakly acidic catalysts (small Pt particles, larger amount of PVP residuals) to overcracking behavior for catalysts with stronger acidity. We find that the Pt/H+ ratio and the number of acid-catalyzed steps extrapolated to zero conversion are better indicators of ideal cracking behavior than the isomers yield.

The Influence of Polyvinylpyrrolidone on the Structure and Optical Properties of ZnO–MgO Nanocomposites Synthesized by the Polymer–Salt Method

The Influence of Polyvinylpyrrolidone on the Structure and Optical Properties of ZnO–MgO Nanocomposites Synthesized by the Polymer–Salt Method

Stable Coloured Micrometric Films from Highly Concentrated Nano-Silver Sols: The Role of the Stabilizing Agents.

The synthesis of highly concentrated aqueous silver nanoparticles (NPs), exploiting different types of polymeric stabilizing agents, has been extensively investigated, especially for the stabilization of spherical yellow nanoparticles. In this context, here, a successful and easy wet chemical method was adopted to synthesize concentrated primary colored (yellow, red, blue and green) sols. The influence of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) in affecting the final stability was finely investigating via UV/Vis spectroscopy, dynamic light scattering, TEM and colorimetric analysis. The next step consisted on the deposition of obtained sols onto a crown-treated polyethylene terephthalate (PET) support to obtain transparent colored micrometric homogeneous films. The fabricated PVP-based Ag films were revealed to be outstandingly UV-stable, contrarily to PVA-based films, probably due to the degradation of the polymer itself. Indeed, after UV aging tests, the PVA macromolecules could be broken and chemically modified (demonstrated by FT-IR analyses). This resulted in there being insufficient macromolecules to efficiently cover the surface of the nanoparticles, meaning that the nanoparticles tended to aggregate with each other, destabilizing the system itself. Hence, the obtained colored films described herein could represent a promising tool for different applications, from color shifting to optoelectronic devices.

Influence of Polyvinyl Pyrrolidone (PVP) on Vanadium-based Compound Composite Performances for Aqueous Zinc-Ion Batteries

Influence of Polyvinyl Pyrrolidone (PVP) on Vanadium-based Compound Composite Performances for Aqueous Zinc-Ion Batteries

An innovative strategy for improving the performance of forward osmosis membrane: stripe-like Turing structure constructed by introducing hydrophilic polyvinylpyrrolidone

Improving the performance of forward osmosis (FO) membranes has always been moving forward. Here we fabricate the novel Turing structures in the active layer (AL) of thin film composite (TFC) membrane through effectively introducing the polyvinylpyrrolidone (PVP) macromolecule with hydrophilicity both in the support layer (SL) and AL. The addition of PVP facilitates the formation of sponge-like pores in the SL and stripe-like Turing structures in the AL. The influence of PVP on the morphology and performance of the membranes was investigated by SEM, AFM, XPS, NMR, FTIR. Compared with the water flux (Jw) of the original composite membrane (approximately 25 L m−2 h−1), TFC-PVP (3:1) membrane with Turing structure achieved better performance (approximately 75 L m−2 h−1), and the reverse solute flux/water flux (Js/Jw) value was as low as 0.02 g/L. This study demonstrated that the Turing structures have a favorable effect on the performance of FO membrane and a promisingly practical application in water treatment.

Effect of surfactants on morphology, structure and photoluminescence properties of Eu-doped ZnO microsphere

The influence of polyvinylpyrrolidone (PVP) and monoethanolamine (MEA) as surfactants on photoluminescence (PL) of Eu-doped ZnO (ZnO:Eu) has been studied. X-ray diffraction (XRD) results show that there are more Eu3+ ions to replace Zn2+ ions into ZnO lattice for ZnO:Eu in the presence of surfactant MEA. From the spectral analysis for ZnO:Eu with different surfactants by Gaussian deconvolution, it can be seen that the use of MEA as a surfactant affects the energy transfer from ZnO host to Eu3+ ions and leads to three new emission peaks, including UV emission (389 nm), violet emission (411 nm) and green emission (506 nm).

Polyvinylpyrrolidone (PVP) hydrogel coating for cylindrical polyurethane scaffolds

The presented study describes a method for the preparation and modification of cylindrical polyurethane structures with polyvinylpyrrolidone (PVP) hydrogel coating. The modified polyurethane scaffolds were fabricated using the phase-inversion technique and intended to be used as a vascular prosthesis. The proposed modification method involves a two-step Fenton-type reaction. Physicochemical analysis (Fourier transform infrared spectroscopy, scanning electron microscopy) confirmed the presence of the hydrogel coating. The influence of PVP and polymerization initiator (cumene hydroperoxide) concentrations on hydrogel’s properties were examined. The higher concentrations of reagent were used, the thicker coating was obtained. After modification, the material’s surface becomes more hydrophilic in comparison to pristine polyurethane. Cytotoxicity assay (MTT test) confirmed that PVP-coating is not toxic. The introduction of hydrogel coating resulted in a significant decrease in the fibrinogen adsorbed to the material’s surface as compared to a non-modified polymer. Platelet adhesion assay demonstrated almost no platelet adhesion to the modified surfaces.

In situ coagulation of yttria‐stabilized zirconia ceramic with enhancement of green body via polyvinyl pyrrolidone crosslink

ABSTRACTIn situ coagulation for yttria‐stabilized zirconia (YSZ) suspension via polyvinyl pyrrolidone (PVP) crosslink is reported. PVP is used to prepare sterically stabilized YSZ suspension. Influence of PVP on the dispersion of YSZ suspension was investigated. It indicates that well disperse YSZ suspension with 0.3 wt % PVP can be prepared. Dimethyl sulfate (DMS) was added at 40 °C to coagulate the suspension after degassing. Influence of DMS content and coagulation temperature on coagulation process and properties of green bodies were investigated. It indicates that sufficiently high viscosity to coagulate the suspension is achieved with the addition of 1 vol % DMS at 60~80 °C. The coagulation mechanism is proposed that the YSZ suspension is destabilized by the self‐crosslink of PVP. Coagulated samples with the highest wet compressive strength of 6.34 MPa could be demolded without deformation by treating 50 vol % YSZ suspension at 60 °C. Dense YSZ ceramics with relative density above 99.1% and flexural strength of 920 ± 90 MPa had been prepared by this method sintered at 1450 °C for 3 h. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48889.

Change of thermophysical properties of polyamides under the influence of polyvinylpyrrolidone

Change of thermophysical properties of polyamides under the influence of polyvinylpyrrolidone

Performance analysis of Polyvinylpyrrolidone

PurposeThe purpose of this paper is to focus on the performance analysis of Polyvinylpyrrolidone (PVP) – Chitosan composite dye transfer inhibitor (DTI) for household laundry. The developed composite DTI is tested against different commercial dyes and detergent powders normally used in the household laundry for its performance.Design/methodology/approachThe DTI article is tested for its performance against five commercial dyes and five commercial detergent compositions. The dye re-deposition behaviour of the control fabric was measured in terms of the colour difference (ΔE) values. The influence of PVP on the washing efficiency of detergent was evaluated against tea, coffee and juice stains.FindingsThe results showed that there is an excellent performance of the developed product noted in terms of DTI performance against reactive, basic and sulfur dyes. The DTI product showed a significantly (p<0.05) less performance against acid and direct dyes. There is no significant differences noted in the stain removal efficiency of the detergent in the presence of PVP in the wash liquor (p>0.05).Originality/valueThe usage of DTI polymer in the household laundry has no significant influence on the detergents performance in terms of stain removing efficiency. The DTI polymer’s function in the wash liquor depends up on the type of polymer used, as they are sensitive to the type of detergent compositions used and the type of dyes bleeds in the wash liquor.

Synthesis, structural, thermal, optical and dielectric properties of chitosan biopolymer; influence of PVP and α-Fe2O3 Nanorods

The present work reports the influence of Polyvinylpyrrolidone (PVP) and hematite (α-Fe2O3) nanorods (NRs) on the physicochemical properties of chitosan (Cs), as an approach to broaden its medical and technological applications. Hematite NRs of 11.4 nm diameter and 87.9 nm crystallite size were prepared by a free-template chemical method. Cs, PVP/Cs and blend loaded with hematite NRs were prepared by solution casting. Significant changes in the films’ surface were clarified using the scanning electron microscope (SEM). Fourier transformation infrared spectroscopy (FT-IR) confirmed the interaction between the NRs and the NH2 and OH functional groups of Cs. DSC measurements showed one endothermic peak assigned to the water elimination, and an exothermic one, in the range 268–287 °C, attributed to the decomposition of saccharine structure in Cs. The swelling properties of the films were sensitive to the pH of the solution. PVP/Cs film showed ~ 85% transmittance in the visible region and its optical band gap narrowed from 5.4 eV to 4.05 eV after loading with 2.0 wt.% hematite. The influence of NRs content on the optical constants of the films is discussed. The dielectric properties depend on the film’ structure. The large Polaron tunneling (LPT) model is the best suitable mechanism for the electric conduction. Due to their high thermal stability and decomposition temperature, transmittance and high conductivity, the prepared films are a candidate for the packaging industry, for use in some medical applications such as treating some chronic wounds, and optical windows and fibers.

Improvement of the photovoltaic performance of Cu2ZnSn(SxSe1−x)4 solar cells by adding polymer in the precursor solution

Kesterite Cu2ZnSn(SxSe1−x)4 (CZTSSe) thin films and related solar cells were successfully fabricated by a facile sol-gel method and selenization process. The influence of Polyvinylpyrrolidone (PVP) additive on the properties of the CZTSSe films and the power conversion efficiency (PCE) of the solar cells were investigated. The results reveal that the qualities of CZTSSe films can be manipulated by incorporating a small amount of PVP. With addition of 1 wt% of PVP, the smoothness and grain size of the CZTSSe films were greatly improved. The contact at the CZTSSe/Mo interface was also improved. As a result, the optimized PCE of solar cells improved from 2.24% to 4.34% after the addition of 1 wt% PVP due to the decrease of recombination at the interfaces. These results suggest that polymer addition in the precursor solution is a promising method for obtaining high quality of CZTSSe films and high-performance solar cells.

KINETICS OF GAS HYDRATES FORMATION AND GROWTH BASED ON MODIFIED ICE

The results of the studies of influence of polyvinylpyrrolidone on the kinetics of formation and the growth of Freon-12 gas hydrate are presented. Based on the P-V-T measurements the degree of conversion of ice into gas hydrate at various concentrations of polyvinylpyrrolidone was calculated. The fact of preservation of inhi-biting properties of polyvinylpyrrolidone in formation of a gas hydrate based on frozen aqueous solutions has been established. The studied polymer shows promoting properties, which leads to an increase in rate of the growth of Freon-12 hydrate based on modified ice.

Influence of polyvinylpyrrolidone, microcrystalline cellulose and colloidal silicon dioxide on technological characteristics of a high-dose Petiveria alliacea tablet

Purpose: Petiveria alliacea L. (Phytolaccaceae) is a perennial shrub used by its immunomodulatory, anticancerogenic and anti-inflammatory properties. This study determined the influence of polyvinylpyrrolidone (PVP), colloidal silicon dioxide (CSD) and microcrystalline cellulose (MC) on the technological characteristic of a high-dose P. alliacea tablet prepared by the wet granulation method.Methodology: The botanical and pharmacognostic analysis of the plant material was firstly performed, followed by a 23 factorial design considering three factors at two levels: (a) the binder (PVP) incorporated in formulation at 10% and 15% (w/w); (b) the compacting agent (CSD) added at 10% and 15% (w/w) and; (c) the diluent (MC) included at 7.33% and 12.46% (w/w). The analysis of pharmaceutical performance and the accelerated and long-term stability of the best prototype were also completed.Result and discussion: The binder, compacting agent and the interaction binder/diluent had a significant impact on breaking force of high-dose P. alliacea tablet. The optimum formula was found to contain 15% (w/w) of CSD, 7.33% (w/w) of MC and 10% (w/w) of PVP. At these conditions, the tablet shows a breaking force of 77.96 N, a friability of 0.39%, a total phenol content of 1.30 mg/tablet and a maximum disintegration time of 6 min.Conclusions: The use of adequate amounts of PVP, MC and CSD as per the factorial design allowed the preparation of a tablet suitable for administration, despite the inappropriate flow and compressibility properties of the P. alliacea powder.

Removal of bovine serum albumin from wastewater using fouling resistant ultrafiltration membranes based on the blends of cellulose acetate, and PVP-TiO2 nanoparticles

Fouling resistant ultrafiltration membranes based on the blends of polyvinylpyrrolidone (PVP), TiO2 nanoparticles and cellulose acetate, CA-PVP-TiO2 (CATP), for removal of bovine serum albumin (BSA) were prepared by using phase inversion process. The influences of PVP and TiO2 on the preparation of phase inverted cellulose acetate (CA) ultrafiltration membrane were explored in terms of morphology study, equilibrium water content (EWC), hydraulic resistance, permeability performance, hydrophilicity, and thermal stability. After the introduction of PVP and TiO2 to the ternary (polymer-solvent-non-solvent) system, the formations of finger-like structures and macro-voids were reduced significantly. An improvement in porosity, average pore size, and hydrophilic nature of the CA membranes were detected after the introduction of PVP and TiO2 into the polymer matrix. The interaction between TiO2 and CA was confirmed and the degradation temperature of the CA membrane was significantly improved. BSA protein removal efficiency, anti-fouling performance, and recycling potential of the UF membranes were investigated. The CATP membrane (10.5 wt % CA: 4 wt % PVP: 2 wt % TiO2) has displayed high BSA removal efficiency and flux recovery ratios (NFR) with enhanced anti-fouling performances for the three fouling/rinsing cycles.