Mixture Of PVA Research Articles

Additive Manufacturing of an Extended-Release Tablet of Tacrolimus.

An extended-release tablet of tacrolimus as once-daily dosing was fabricated using 3D printing technology. It was developed by combining two 3D-printing methods in parallel. Indeed, an optimized mixture of PVA, sorbitol, and magnesium stearate as a shell compartment was printed through a hot-melt extrusion (HME) nozzle while an HPMC gel mixture of the drug in the core compartment was printed by a pressure-assisted micro-syringe (PAM). A 3D-printed tablet with an infill of 90% was selected as an optimized formula upon the desired dissolution profile, releasing 86% of the drug at 12 h, similar to the commercial one. The weight variation, friability, hardness, assay, and content uniformity determination met USP requirements. A microbial evaluation showed that the 3D-printed tablet does not support microbial growth. SEM analysis showed smooth surfaces with multiple deposited layers. No peak interference appeared based on FTIR analysis. No decomposition of the polymer and drug was observed in the printing temperature, and no change in tacrolimus crystallinity was detected based on TGA and DSC analyses, respectively. The novel, sTable 3D-printed tablet, fabricated using controllable additive manufacturing, can quickly provide tailored dosing with specific kinetic release for personalized medicine at the point-of-care.

Gel Polymer-Based Composite Solid-State Electrolyte for Long-Cycle-Life Rechargeable Zinc–Air Batteries

Developing high-performance, safe, and flexible solid-state electrolytes (SSEs) for rechargeable solid-state zinc–air batteries (ZABs) is becoming increasingly crucial but remains fraught with tremendous challenges. Herein, a novel multinetwork cross-linked composite gel electrolyte (PVAA-Cellulose) was constructed by introducing poly(acrylic acid) (PAA) and ultrafine cellulose to the poly(vinyl alcohol) (PVA) gel electrolyte. By virtue of the extensive porous network and hydrogen bonding, the PVAA-Cellulose SSEs achieve optimal water retention, thermal stability, and high ionic conductivity of 123 mS cm–1 compared with PVAA (mixture of PVA and PAA). The investigation of the effects of different SSEs on zinc anodes after ZAB cycling reveals that PVAA-Cellulose SSE can effectively inhibit dendrite growth and oxidation byproduct generation on zinc anodes, which contributes to the long-term cycling stability of ZABs. As a result, solid-state ZABs assembled with PVAA-Cellulose SSEs possess a high power density of 74 mW cm–2, a specific capacity of 724 mAh gZn–1, and a long cycle stability of 54 h as well as the outstanding flexibility exhibited by the flexible ZAB devices.

Watered-Based Graphene Dispersion Stabilized by a Graft Co-Polymer for Electrically Conductive Screen Printing

Graphene conductive inks have attracted significant attention in recent years due to their high conductivity, corrosion resistance, and environmentally friendly nature. However, the dispersion of graphene in aqueous solution is still challenging. In this work, we synthesized an amphiphilic graft copolymer, polyvinyl alcohol-g-polyaniline (PVA-g-PANI), and studied the graphene dispersion prepared with the graft copolymer by high-speed shear dispersion. The amphiphilic graft copolymer can be used as a stabilizer and adhesive agent in graphene dispersion. Given the steric hindrance of the graft copolymer, the stability of graphene dispersion is improved by decreasing the probability of π-π stacking. PVA-g-PANI has a better stability on graphene dispersion than carboxymethylcellulose sodium (CMC-Na) and a mixture of PVA and PANI. The graft copolymer has only a slight effect on the conductivity of graphene dispersion due to the existence of conductive PANI, which is beneficial for preparing the graphene dispersion with good conductivity and adhesion. Graphene dispersion is well-adapted to screen printing and is very stable with regard to the sheet resistance bending cycle.

Effect of bentonite clay particles on the behavior of foam stabilized by SDS–PVA complexes

In recent years, there has been increased interest in studies on the stabilization of liquid foams with solid particles. In such three-phase foams it is possible to completely stop the process of syneresis, reduce coalescence and diffusion of gas. The presence of particles can significantly increase the time of the foam lifetime. Such Pickering foams are also of interest as an environmentally friendly and cost-effective alternative to surfactants and high molecular weight foaming agents. This work is focused on investigating the foam stability containing SDS–PVA composite foaming agents with bentonite clay particles. Foam stability was characterized via the time of foam drainage. The stability of foams of SDS–PVA mixtures in absence and presence of bentonite particles was determined. The stability of foams is higher in presence of the bentonite particles.

Printed Low-Cost PEDOT:PSS/PVA Polymer Composite for Radiation Sterilization Monitoring.

During the γ-radiation sterilization process, the levels of radiation exposure to a medical device must be carefully monitored to achieve the required sterilization without causing deleterious effects on its intended physical and chemical properties. To address this issue, here we have demonstrated the development of an all-printed disposable low-cost sensor that exploits the change in electrical impedance of a semi-interpenetrating polymer network (SIPN) composed of poly(vinyl alcohol) (PVA) and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) as a functional polymer composite for radiation sterilization monitoring applications. Specifically, the PEDOT:PSS acts as the electrically conductive medium, while the PVA provides the ductility and stability of the printed sensors. During irradiation exposure, chain scission and cross-linking events occur concurrently in the PEDOT:PSS and PVA polymer chains, respectively. The concurrent scissoring of the PEDOT polymer and cross-linking of the PVA polymer network leads to the formation of a stable SIPN with reduced electrical conductivity, which was verified through FTIR, Raman, and TGA analysis. Systematic studies of different ratios of PEDOT:PSS and PVA mixtures were tested to identify the optimal ratio that provided the highest radiation sensitivity and stability performance. The results showed that PEDOT:PSS/PVA composites with 10 wt % PVA produced sensors with relative impedance changes of 30% after 25 kGy and up to 370% after 53 kGy (which are two of the most commonly used radiation exposure levels for sterilization applications). This composition showed high electrical impedance stability with less than ±5% change over 18 days after irradiation exposure. These findings demonstrate the feasibility of utilizing a printing technology for scalable manufacturing of low-cost, flexible radiation sensors for more effective monitoring of radiation sterilization processes.

Facile Fabrication of Magnetic Poly(Vinyl Alcohol)/Activated Carbon Composite Gel for Adsorptive Removal of Dyes

Activated carbon (AC) has been widely utilized for the adsorption of pollutants from water. However, it is difficult to recycle the AC after adsorption. In this paper, we report a facile one-pot approach to fabricate magnetic poly(vinyl alcohol)/AC composite gel (mPVA/AC CG) by dropwise addition of an aqueous mixture of PVA, AC and iron ions into the ammonia solution. The obtained mPVA/AC CG after freeze-drying shows porous microstructure and favorable magnetic properties. The utilization of mPVA/AC CG for adsorptive removal of methylene blue (MB) and methyl orange (MO) dyes from water was investigated. The mPVA/AC CG not only exhibited good adsorption performance for both MB and MO dyes but also could be readily recycled using a magnet after adsorption. The adsorption process was well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. Considering the simple fabrication process, good adsorption performance and favorable magnetic separation capability, this work provides a viable strategy for combining the features of AC and magnetic gel for fabrication of applicable magnetic adsorbent.

The effect of composition on mechanical properties of biodegradable plastic based on chitosan/cassava starch/PVA/crude glycerol: Optimization of the composition using Box Behnken Design

Synthetic plastic waste is one of the most concerning problems on our earth today. For that reason, many researchers are currently developing biodegradable plastics as a substitute for synthetic plastics for food packaging purposes. However, biodegradable plastics have poor mechanical properties because of their characterteristics as biopolymers, such as brittle and fragile. Chitosan has often been used as an additive in starch or PVA mixtures because of its biodegradability. Meanwhile, PVA itself is widely used in polymer blends because it can increase the flexibility and tensile strength of biodegradable plastic. The aim of this study is to develop a biodegradable plastic based on chitosan, cassava starch, and PVA with the addition of crude glycerol as a plasticizer. Observation of the effect of chitosan, starch, and PVA content on the mechanical properties of chitosan/cassava starch/PVA biodegradable plastics were carried out using Design-Expert Version 10.0.1 with Response Surface Methodology-Box Behnken Design. The composition of chitosan, starch, and PVA was varied from the range of 1–3 g, 1–5 g, and 1–5 g respectively. The optimization results suggest that biodegradable plastic with the composition of 3 g chitosan, 1 g starch, and 5 g PVA has the highest tensile strength and elongation values. The optimum biodegradable plastic showed that it was degraded by 50.45% of its weight after being buried in the soil for 30 days. Furthermore, the optimum biodegradable plastic can be investigated for its characteristics in further research.

Optimization of Additional Composition Variations ZnO Nanoparticles on The Characteristics of Porous Hydroxypatite as Bone Filler

Research on the synthesis and characterization of porous hydroxyapatite with the addition of ZnO nanoparticles has been carried out through a combination of foam immersion and injection methods. This research was conducted to optimize the previous research by increasing the variation of ZnO composition and adding the injection method to the research process. The materials used in this research include hydroxyapatite nanoparticles, ZnO nanoparticles, Aquades, PVA and polyurethane foam. Manufacturing is done by immersing polyurethane foam into a slurry. Slurry is a mixture of PVA and hydroxyapatite solutions with variations in the addition of ZnO nanoparticles (8 wt%, 10 wt%, 12 wt%, and 14 wt%). Then inject the remaining slurry into the foam. After that the sample was dried and heated at a temperature of 650ºC to remove foam and PVA, then the sample was sintered at a temperature of 1200ºC for 3 hours. Based on SEM analysis, porosity test, and compressive strength test, the best results were shown by sample IV because it had a pore diameter of 142.9 – 371.4 m with a porosity of 69.983%, a compressive strength value of 1.8653 MPa and non-toxic. The best results have not met the standard for bone filler application. In further research, improvements need to be made by using other additives such as ZrO2, so that it can improve the mechanical properties of porous hydroxyapatite to meet standard bone filler applications.

Partially hydrolyzed polyvinyl alcohol for fusion-based pharmaceutical formulation processes: Evaluation of suitable plasticizers.

The present study evaluates the effect of several pharmaceutical plasticizers on the thermo-physical and physicochemical properties of partially hydrolyzed poly(vinyl alcohol) (PVA) used in fusion-based pharmaceutical formulation processes. Specifically, the effect of mannitol (MAN), sorbitol (SOR), sucrose (SUC), anhydrous citric acid (CA), triethyl citrate (TEC) and low-molecular weight polyethylene glycol (PEG400) on PVA's melting properties, physical state and thermal degradation was evaluated via differential scanning calorimetry (DSC), powder X-ray diffractometry (pXRD) and thermo-gravimetric analysis (TGA). Results showed that the use of MAN, SOR, SUC and PEG400 led to the reduction of PVA's melting onset temperature, while MAN, SUC, CA and SOR were amorphously dispersed within PVA's matrix, and the addition of SUC and CA resulted in significant reduction of PVA's crystallinity. TGA results showed the formation of thermally highly unstable PVA mixtures in the cases of CA and TEC (degradation started from ~150°C and ~125°C, respectively), while significant molecular interactions were identified by FTIR in the cases of PVA-MAN, PVA-SOR and PVA-SUC. Hot-stage polarized microscopy (HSM) revealed PVA's melt miscibility only with MAN and SOR, while melt flow index (MFI) measurements showed that the use of MAN, SOR and PEG400 resulted in a significant improvement of PVA's melt flow properties. Finally, MD simulations were in close agreement with the experimental observations, indicating that they can be considered as a promising tool for the theoretical modelling of such systems.

커플링제 첨가가 PVA와 무기입자 혼합함침 처리에 미치는 영향

커플링제 첨가가 PVA와 무기입자 혼합함침 처리에 미치는 영향

Quaternized graphene oxide modified PVA-QPEI membranes with excellent selectivity for alkali recovery through electrodialysis

Composite anion exchanges membranes are prepared by incorporating quaternized graphene oxide (QGO) within poly(vinyl alcohol) (PVA) or the mixture of PVA and quaternized polyethyleneimine (QPEI), followed by cross-linking with formaldehyde. The PVA-QGO series of membranes have low ion exchange capacities (IECs) of 0.10–0.37mmol/g and low water uptakes (WR) of 16.1%–22.0%, leading to high area resistances (>60Ωcm2). The PVA-QPEI-QGO series of membranes show much lower area resistances of 2.47–6.04Ωcm2, which is ascribed to the improved IECs (0.86–1.37mmol/g) and WR (46.8%–71.4%). Both series of membranes show higher alkali resistance than commercial membrane AMV. Their weight losses are in the range of 0.5%–8.9% after immersion in 60°C 2mol/L NaOH alkaline solution for 32 days, while the value of AMV membrane is 19.2%. When utilized for electrodialysis (ED) application to recover NaOH from NaOH/Na2WO4 mixture, the prepared membranes exhibit high selectivity, as evidenced by the low leakage ratio of Na2WO4. The leakage ratio of the optimized composite membrane to WO42− is only 5.1%, while the leakage ratio of AMV membrane is up to 61.4%. To explore this reason, the composite membranes are selected for the ED separation of monovalent ions. The separation efficiency (S) of the optimized membrane is 83.9%, which is similar to the value of commercial anion selective membrane NEOSEPTA® ACS (88.7%), confirming further the selectivity of the composite membranes.

Magnetic polymer microcapsules: One-step template/surfactant-free preparation and Pt decoration for catalytic reduction of aromatic nitro compounds

Rapid and scalable preparation of polymer-based magnetic microcapsules (MMCs) without employing any templates and surfactants is still a challenge. Herein, we present a one-step template/surfactant-free strategy for fast and large-scale fabrication of poly(vinyl alcohol) (PVA)-based MMCs. The MMCs are formed from simultaneous creation of magnetic Fe3O4 nanoparticles and crosslinking of PVA chains, which is achieved by simple addition of ammonia solution into the preformed water-in-oil (W/O) emulsion comprising castor oil, aqueous mixture of PVA and iron salts. The size and shell thickness of MMCs could be readily controlled by fine tuning the process parameters. Furthermore, this approach allows for incorporation of additional functional nanoparticles into the PVA shell of MMCs, as demonstrated by the fabrication of Pt nanoparticles decorated MMCs (Pt-MMCs) in this study. The Pt-MMCs displayed favorable catalytic activity for reduction of aromatic nitro compounds (e.g., 4-nitrophenol and 4-nitroaniline), and could be conveniently recycled using magnet and reused for > ten times without obvious decline of catalytic activity. This work thus opens a new pathway for facile fabrication of property-tailored MMCs to meet the requirements of various applications.

Experimental Investigation on Compressive Toughness of the PVA-Steel Hybrid Fiber Reinforced Cementitious Composites

In order to achieve the whole process control of crack formation of engineered cementitious composites (ECC) under loading and improve the mechanical properties of ECC, PVA-steel hybrid fiber reinforced cementitious composites (HyFRCC) was proposed by mixing steel fibers with traditional ECC. And the key parameters to affect the HyFRCC performance are PVA fiber content, steel fiber content and aspect ratio of steel fiber. In order to investigate the mechanical properties of PVA-steel HyFRCC such as the compressive toughness, 15 PVA-steel HyFRCC specimens with different volume fraction of steel fiber and PVA fiber, together with 1 non-fibrous cementitious composites specimen and 3 ECC specimens with PVA fiber only for comparison were designed and uniaxial compression tests were conducted. Furthermore, the effect of fiber content, fiber type and fiber geometrical characteristic on the compressive toughness of HyFRCC were analyzed. The results show that PVA fiber content, steel fiber content and aspect ratio of steel fiber have little impact on the uniaxial compressive strength of the PVA-steel HyFRCC, while the peak strain, compressive toughness and the post-peak ductility of PVA-steel HyFRCC are improved significantly due to fiber hybridization. The formation of large scale cracks of ECC specimens after post-peak loading is restrained effectively with the addition of steel fiber. The mixture of PVA and steel fiber has a remarkable effect on the improvement of ECC compression toughness and crack control. It indicates that the energy dissipation and damage control capacity of the structural component with PVA-steel HyFRCC under seismic loading will be enhanced.

Electrospun of poly(vinyl alcohol) nanofiber as carrier of Garcinia mangostana L. pericarp extract

The extract of Garcinia mangostana pericarp (GP) contains xanthones that possesses diverse therapeutic effects. Nevertheless, it has poor solubility in water and poor absorption. Incorporation of GP extracts in nano-delivery system is a promising way to increase GP extracts solubility and absorption. The objective of this study is to prepare poly(vinyl alcohol) (PVA) mats GP nanofiber by electrospinning method. The nanofibers that contained GP extracts were synthesized in a mixture of PVA using single nozzle electrospinning method. The electrospinning parameters used have 13 kV potential with the nozzle-collector distance of 13 cm and flow rate 10 μl/minute. Scanning electron microscopic (SEM) was evaluated. From the SEM analysis, the average diameter of the fibers was on the nanoscale size. Hence in this study, the PVA nanofiber and PVA/GP nanofiber mats were successfully prepared using the electrospinning method. In addition, applying high voltage in the electrospinning process did not destroy the chemical structure of GP extracts indicated by retained antibacterial activity in vitro. These GP nanofiber mats may provide the good alternative for drug delivery system.

Hydrogels of chitosan as bioadsorbents of Cr (VI) in aqueous systems

Rapid and scalable preparation of polymer-based magnetic microcapsules (MMCs) without employing any templates and surfactants is still a challenge. Herein, we present a one-step template/surfactant-free strategy for fast and large-scale fabrication of poly(vinyl alcohol) (PVA)-based MMCs. The MMCs are formed from simultaneous creation of magnetic Fe3O4 nanoparticles and crosslinking of PVA chains, which is achieved by simple addition of ammonia solution into the preformed water-in-oil (W/O) emulsion comprising castor oil, aqueous mixture of PVA and iron salts. The size and shell thickness of MMCs could be readily controlled by fine tuning the process parameters. Furthermore, this approach allows for incorporation of additional functional nanoparticles into the PVA shell of MMCs, as demonstrated by the fabrication of Pt nanoparticles decorated MMCs (Pt-MMCs) in this study. The Pt-MMCs displayed favorable catalytic activity for reduction of aromatic nitro compounds (e.g., 4-nitrophenol and 4-nitroaniline), and could be conveniently recycled using magnet and reused for > ten times without obvious decline of catalytic activity. This work thus opens a new pathway for facile fabrication of property-tailored MMCs to meet the requirements of various applications.

Silicon dioxide/poly(vinyl alcohol) composite hydrogels with high mechanical properties and low swellability

ABSTRACTPoly(vinyl alcohol) (PVA) hydrogels with tissue‐like viscoelasticity, excellent biocompatibility, and hydrophilicity have been considered as promising cartilage replacement materials. However, the low mechanical properties of pure PVA hydrogels limit their applications for bearing complicated loads. Herein, we report silicon dioxide (SiO2)/PVA composite hydrogels fabricated by fabricated cyclically freezing/thawing the aqueous mixture of PVA and methyltrimethoxysilane (MTMS). MTMS hydrolyzes and forms SiO2 particles in situ to reinforce PVA hydrogel. Meanwhile, silanol group condenses with hydroxyl groups of PVA and chemically bonds with PVA. The resulting SiO2/PVA hydrogels exhibit much better mechanical properties than bare PVA hydrogel. In addition, the composite hydrogels keep very low swellable property. This prepared composite hydrogels are promising in a variety of biomedical applications such as artificial articular cartilage, drug delivery, and biosensors. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46895.

Synthesis and Characterization by Ellipsometry of Cationic Membranes for Fuel Cells

In this study, cationic membranes based on poly (vinyl alcohol) (PVA) were synthesized, crosslinked with citric acid (carboxylic group) and 4-sulpho-phthalic acid (sulphonic group) for application as proton-conducting membranes of H3O+. The membranes were prepared from the mixture of PVA with the crosslinking agents (CA), previously dissolved and separated with the mixture of these. The CAs proportions used were 10%, 30% and 50%, based on the weight of PVA, and they were crosslinked at the temperatures of 120oC and 140oC. The films were characterized by thermal stability using TGA, spectroscopy ellipsometry (relative refractive index and real part of dielectric constant), swelling degree (water absorption) and conductivity, using electrochemical impedance spectroscopy (EIS). A variation in the refractive index as a function of CA concentration was observed. This fact was corroborated with the results of dielectric constant, because the higher concentration of hydrophilic group added to the film, higher the values of dielectric constant. The membranes which showed lowest swelling degree values were crosslinked with 4-sulpho-phthalic acid (sulphonic group), for example, the PVA membrane crosslinked with 50% of 4-sulpho-phtalic acid, at 140oC, showed 6.4% of water absorption, while the membrane PVA crosslinked with the same content of CA, but of citric acid, and temperature, presented 15.8%. The conductivity of some membranes, under the assay condition evaluated, was the same order of magnitude as the commercial membranes, Nafion®. The synthesized membranes have been showing potential application as cationic polymer membranes for the transport of H3O+.

Accelerated full-thickness wound healing via sustained bFGF delivery based on a PVA/chitosan/gelatin hydrogel incorporating PCL microspheres

Herein, a hybrid hydrogel/microsphere system is introduced for accelerated wound healing by sustained release of basic fibroblast growth factor (bFGF). The hydrogel is composed of a mixture of PVA, gelatin and chitosan. The double-emulsion-solvent-evaporation method was utilized to obtain microspheres composed of PCL, as the organic phase, and PVA, as the aqueous phase. Subsequently, various in-vitro and in-vivo assays were performed to characterize the system. BSA was used to optimize the release mechanism, and encapsulation efficiency in microspheres, where a combination of 3% (w/v) PCL and 1% (w/v) PVA was found to be the optimum microsphere sample. Incorporation of microspheres within the hydrogel substrate also led to a zero-order release kinetics. Results from SEM images, also represented an average porosity of 54%, and average mean pore size of 35 ± 7 μm for the hydrogel system, and the diameter of 5 ± 2 μm for the microspheres. Moreover, in vivo study including wound healing process, and histological analysis regarding re-epithelization, angiogenesis, inflammation, fibroblast genesis and collagen formation were performed using Hematoxyline-Eosin (H&E) staining, Periodic Acid–Schiff (PAS) staining and Masson’s Trichrome staining. In-vivo results represented that sustained delivery of bFGF promoted by biocompatibility of PVA/chitosan/gelatin hydrogel, significantly contribute to accelerated wound healing.

Effect of amine structure on CO2 capture by polymeric membranes

Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO2 separation properties over H2. However, the CO2 permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO2 determining agent in the current CO2 capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO2 separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO2 permeability coefficient of MEA containing membrane was 604 barrer with CO2 selectivity of 58.5 over H2, which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO2-selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO2 separation performance.

Fabricating graphene-titanium composites by laser sintering PVA bonding graphene titanium coating: Microstructure and mechanical properties

Abstract Graphene reinforced titanium (Ti-Gr) nanocomposite was prepared by laser sintering of the mixture of PVA bonding graphene sheets and titanium powders. During laser sintering process, the survival and uniform dispersion of graphene have been demonstrated, which embedded in Ti matrix, and formed Ti-Gr nanocomposites. Microstructures and components of the nanocomposites were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Raman spectroscopy. The survival of graphene sheets in nanocomposite is due to rapid heating/cooling in laser sintering process. Hardness measurements showed that the laser sintered Ti-Gr nanocomposites achieved more than 2-fold Vickers Hardness value of barely sintered Ti.