Polyvinyl Alcohol Concentration Research Articles

Durability and Mechanical Properties of Nano-SiO2 and Polyvinyl Alcohol Fiber-Reinforced Cementitious Composites Subjected to Saline Freeze–Thaw Cycles

To investigate the effects of nano-SiO2 (NS) and polyvinyl alcohol (PVA) fibers on the durability and mechanical properties of cementitious composites subjected to saline freeze–thaw cycling, a series of PVA fiber-reinforced cementitious composite (PFRCC) specimens were prepared using various fiber contents, and a series of NS and PVA fiber-reinforced cementitious composite (NPFRCC) specimens were prepared using various combinations of NS and fiber contents. Durability and fracture toughness tests were subsequently conducted on the specimens after different numbers of saline freeze–thaw cycles. The results indicate that the degradation of material properties can be divided into slow and accelerated damage stages before/after 50 freeze–thaw cycles. The durability and fracture toughness of the specimen series tended to increase, then decrease with increasing NS and PVA contents, suggesting optimum levels. When the PVA fiber content was 0.5%, PFRCC specimens had the best durability after saline freeze–thaw cycles; when the NS and PVA fiber contents were 1.0% and 0.5%, respectively, NPFRCC specimens had the best durability and fracture properties, and the initiation toughness, destabilization toughness, and fracture energy after 100 saline freeze–thaw cycles were 120.69%, 160.02%, and 451.31%, respectively. The results of this study may guide future exploration of the durability and mechanical properties of concrete subjected to freeze–thaw action.

Ionic thermoelectricity of salt-free PVA-hydrogel

As polyvinyl alcohol (PVA) hydrogels have shown a high potential as an ionic thermoelectric generator, this paper aims to study the thermoelectric (TE) power of salt-free PVA hydrogel. Ionic thermoelectric performance, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) are measured at different relative humidities. Findings show that salt-free PVA hydrogels can achieve a relatively high Seebeck (9.26 mV K−1) using only surrounding moisture. Hydrogels with low PVA content have a more stable TE output than hydrogels with high PVA content in high relative humidity conditions. Embedded Ni-foam-CNT electrodes stabilize performance, reduce noise, and provide superior capacitance, resistance, and thermoelectric performance over direct drop-casting of CNT on hydrogels. Recommended operating relative humidity (RH) ranges between 40 % and 60 %, while recommended PVA content ranges from 10 % to 15 % mass ratio of PVA in water. The results pave the way for using PVA hydrogels as thermoelectric devices in biocompatible applications.

The Effect of Polyvinyl Alcohol Addition on the Optical Properties and Oxygen Detection Performance of Titanium Dioxide and Methylene Blue Nanocomposite Colorimetric Indicators.

In this study, we investigated the impact of polyvinyl alcohol (PVA) incorporation on the optical properties and oxygen detection performance of a titanium dioxide/methylene blue (TiO2/MB) nanocomposite colorimetric indicator for packaging applications. The nanocomposite was synthesized via mechanical milling of TiO2 nanoparticles with MB and citric acid. PVA, at varying concentrations (0, 3, 9, and 14 wt%), was introduced during the wet milling process to produce a homogeneous composite film. Spin coating was employed to fabricate TiO2/MB nanocomposite films for oxygen detection evaluation. The influence of PVA loading on the films' chemical functionalities and surface morphologies was assessed using Fourier-transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FE-SEM). The indicator's activation process, involving a color change between bleached and colored states, and its recovery time were monitored via optical imaging and UV-VIS-NIR spectrophotometry. The results revealed that a PVA content of 9 wt% yielded well-defined films with enhanced stability of the TiO2/MB nanocomposite's oxygen detection performance.

Characterization of polyvinyl alcohol and vitex negundo blended bio nanofilm for wound healing scaffold

Polyvinyl alcohol blended nanofilms have shown great promise as a material for wound healing applications because of their biocompatibility, biodegradability, and antibacterial characteristics. This article has typically utilized electrospinning to create a scaffold for wound healing meanwhile investigating the characteristics of the polyvinyl alcohol (PVA) and vitex negundo (VN) blend nanofilm. The PVA concentrations were kept at 10% Weight/Volume (W/V), which was then mixed with VN solution at various volumetric ratios and electrospun into nanofilms. Field Emission Scanning Electron Microscopy (FESEM) was used to determine and analyze the nanofiber diameter. The plant extract concentration and the viscosity of the electrospinning solution influenced the fiber diameter to grow from 120.32 nanometers (nm) to 171.11 nanometers (nm). Fourier Transform Infrared Spectroscopy (FTIR) verifies the interaction between plant extract and PVA and records a new peak between 1731 and 1750 cm−1, which represents the production of the ester group. The swellability of the developed sample was studied which is negligibly reduced when the plant extract was added. In comparison to both Gram-positive and Gram-negative bacteria, the pure plant extract and composite nanofibrous web demonstrated greater antibacterial activity. PVA-blended nanofilms can promote cell migration, proliferation, and differentiation, hence promoting wound healing by creating a moist environment.

Effects of PVA and yerba mate extract on extruded films of carboxymethyl cassava starch/PVA blends for antioxidant and mechanically resistant food packaging

Global concerns over environmental damage caused by non-biodegradable single-use packaging have sparked interest in developing biomaterials. The food packaging industry is a major contributor to non-degradable plastic waste. This study investigates the impact of incorporating different concentrations of polyvinyl alcohol (PVA) and yerba mate extract as a natural antioxidant into carboxymethyl cassava starch films to possibly use as active degradable packaging to enhance food shelf life. Films with starch and PVA blends (SP) at different ratios (SP radios of 100:0, 90:10, 80:20 and 70:30) with and without yerba mate extract (Y) were successfully produced through extrusion and thermoforming. The incorporation of up to 20 wt% PVA improved starch extrusion processing and enhanced film transparency. PVA played a crucial role in improving the hydrophobicity, tensile strength and flexibility of the starch films but led to a slight deceleration in their degradation in compost. In contrast, yerba mate extract contributed to better compost degradation of the blend films. Additionally, it provided antioxidant activity, particularly in hydrophilic and lipophilic food simulants, suggesting its potential to extend the shelf life of food products. Starch-PVA blend films with yerba mate extract emerged as a promising alternative for mechanically resistant and active food packaging.

Stability and release mechanism of double emulsification (W1/O/W2) for biodegradable pH-responsive polyhydroxybutyrate/cellulose acetate phthalate microbeads loaded with the water-soluble bioactive compound niacinamide

Microbeads of biodegradable polyhydroxybutyrate (PHB) offer environmental benefits and economic competitiveness. The aim of this study was to encapsulate a water-soluble bioactive compound, niacinamide (NIA), in a pH-responsive natural matrix composed of PHB and cellulose acetate phthalate (CAP) by double emulsification (W1/O/W2) to improve the encapsulation efficiency (%EE) and loading capacity (%LC). PHB was produced in-house by Escherichia coli JM109 pUC19-23119phaCABA-04 without the inducing agent isopropyl β-D-1-thiogalactopyranoside (IPTG). The influences of PHB and polyvinyl alcohol (PVA) concentrations, stirring rate, PHB/CAP ratio and initial NIA concentration on the properties of NIA-loaded pH-responsive microbeads were studied. The NIA-loaded pH-responsive PHB/CAP microbeads exhibited a spherical core-shell structure. The average size of the NIA-loaded pH-responsive microbeads was 1243.3 ± 11.5 μm. The EE and LC were 33.3 ± 0.5 % and 28.5 ± 0.4 %, respectively. The release profiles of NIA showed pH-responsive properties, as 94.2 ± 3.5 % of NIA was released at pH 5.5, whereas 99.3 ± 2.4 % of NIA was released at pH 7.0. The NIA-loaded pH-responsive PHB/CAP microbeads were stable for >90 days at 4 °C under darkness, with NIA remaining at 73.65 ± 1.86 %. A cytotoxicity assay in PSVK1 cells confirmed that the NIA-loaded pH-responsive PHB/CAP microbeads were nontoxic at concentrations lower than 31.3 μg/mL, in accordance with ISO 10993-5.

Formulation of Salam (Syzygium polyanthum (wight) walp) Leaves Ethanolic Extract Matrix Patch and Its Evaluation

The total flavonoid content in salam leaves has an anti-inflammatory activity at a dose of 2.1% w/w. For topical anti-inflammatory, a matrix patch has a delivery mechanism that drugs pass through in the skin in a controlled for an extended period. Polymers were the patch's main component to control the drug release. Polyvinyl alcohol (PVA) and alpha-cellulose (AC) were polymers that can increase the rate of drug diffusion and form a strong film layer. Salam leaves were extracted by maceration using ethanol 96%. Matrix patches were made with a combination of PVA and AC in ratios 1:1; 3:1; 1:3. The patches were tested for physicochemical properties. The stability test was conducted at 4, 25, and 40 temperatures for 8 h, respectively. Statistical analysis of the test data used One Way ANOVA with a confidence level of 95%. The results showed that the high concentration of PVA significantly affected the weight and moisture content but did not affect the organoleptic thickness, folding endurance, and pH of the matrix patch. The best matrix patch of salam leaves ethanolic extract was PVA and AC of 3:1 because it met the requirements for the matrix patch, including the weight of 1.96-2.06 grams, thickness of 1.15-1.18 mm, folding endurance >300 times, humidity 25.75 – 30.17% and pH 6.3 – 7.1. The patch contains flavonoids with Rf values for extract and patch of 0.95 and 0.96, respectively. Further study, in vivo anti-inflammatory test is necessary.

Modification of High-Density Polyethylene with a Fibrillar-Porous Structure by Biocompatible Polyvinyl Alcohol via Environmental Crazing.

Polymer/polymer nanocomposites based on high-density polyethylene (HDPE) and biocompatible polyvinyl alcohol (PVA) were prepared by tensile drawing of HDPE in the PVA solutions via environmental crazing. The mechanism of this phenomenon was described. The HDPE/PVA nanocomposites were studied by the methods of scanning electron microscopy, atomic force microscopy, gravimetry, tensile tests, and their composition, properties, and performance were characterized. The content of PVA in the HDPE/PVA nanocomposites (up to 22 wt.%) was controlled by the tensile strain of HDPE and concentration of PVA in the solution. Depending on the content of PVA, the wettability of the HDPE/PVA nanocomposite (hydrophilic-lipophilic balance) could be varied in a broad interval from 45 to 98°. The modification of HDPE by the biocompatible PVA offers a beneficial avenue for practical applications of the HDPE/PVA composites as biomedical materials, packaging and protective materials, modern textile articles, breathable materials, membranes and sorbents, etc.

Enhancement in Dissolution Profile of Cilnidipine by Nanonization Technique: Optimization by Box-Behnken design

Objectives: Cilnidipine has limited 25-30% of bioavailability due to BCS class II category drug. The aim of present work was to improve the solubility followed by dissolution rate of cilnidipine by formulation of nanosuspension. Materials and Methods: The nanosuspensionwas developed usingnanoprecipitation techniqueaidingultra-sonication with solvent (Dimethyl sulfoxide), antisolvent (water) and stabilizer (polyvinyl alcohol). The nano formulation was statistically optimized using Design Expert software by theBox-Behnken design. The concentration of Poly Vinyl Alcohol, Volume of Antisolvent and Stirring Time were considered as independent factors whereas Particle size and polydispersity index were considered as dependent factors. Results: The particle size of nanosuspension was found 178.57nm with narrow polydispersity index of 0.130. The microscopy study confirmed amorphous nature particles with rough surface. The zeta potential of 4.55 ±2.78 for optimized formulation finds stability of formulation during storage. The differential scanning calorimetry study and X-ray diffraction pattern showed the crystalline cilnidipine drug was converted to amorphous form upon precipitation into nanoparticles. Due to the nanonization of cilnidipine, the dissolution profile was noted as 92.41±3.56% which was significantly improved as compared with plain drug release data. The stability data showed satisfactory result for 2 months. Conclusion: It is summarized that the nanoprecipitation technique with ultra-sonication is approaching method for the formulation of homogenous nanosuspension with uniform sized dispersion of cilnidipine. Therefore, it can be assumed that the upon the enhancement in dissolution rate, the cilnidipine loaded nanosuspension may lead to improved absorption of drug from intestine followed by significant improvement in bioavailability.

Effect of LLZTO Tablet Pressing Process on Electrochemical Properties of Button Batteries

AbstractThe garnet‐type Li6.4La3Zr1.4Ta0.6O12 (LLZTO) is a widely studied solid‐state electrolytes (SSEs) due to its high ionic conductivity and electrochemical stability. However, the conventional preparation process of LLZTO electrolyte tablets has encountered several issues such as powder embedment in the mold gaps and inadequate bonding between powders, leading to fragile electrolyte tablets that are prone to cracking. In this study, the effects of LLZTO electrolyte tablet pressing process parameters, including mixed powder content, polyvinyl alcohol (PVA) content and cold pressing pressure, on the electrochemical properties of button cells were investigated. The results indicated that the produced solid‐state electrolyte tablets with high quality, low interfacial resistance and low surface passivation layer (Li2CO3) content was obtained by using 0.8 g of mixed powder content, 0.7 g of PVA content and 20Mpa pressure. The interface resistance decreased from 2927.1 Ω to 1069.7 Ω under these conditions. Additionally, the Li symmetric cell treated with adhesive exhibited stable cycling for over 400 hours at 25 °C under a current density of 0.1 mA ⋅ cm−2.

Application of iron-manganese oxide fillers in bioretention facility: Enhanced removal of antibiotics and conventional contaminants

Bioretention facilities are common source reduction facilities, but traditional fillers are not effective in reducing emerging contaminants such as antibiotics. Although Fe-Mn oxides have been extensively explored, their removal of emerging contaminants and application in the sponge city have not yet been addressed. Therefore, this study aims to address this limitation by developing Fe-Mn oxide fillers. In this research, the optimal preparation conditions (Fe/Mn mole ratio, polyvinyl alcohol (PVA) concentration, and filler particle size) and influencing factors (filler dosage, initial pollutant concentration, pH, temperature, and co-existing ions) were investigated using a typical antibiotic, norfloxacin (NOR), as the target contaminant. The removal mechanism of NOR was investigated by SEM, FTIR, and XPS characterizations. Subsequently, the fillers were applied to bioretention facilities with different filling modes (layered and mixed) to evaluate their effectiveness in removing NOR and conventional pollutants at different recurrence periods, drought periods, and pollutant influent concentrations. The study indicated that Fe-Mn oxide filler (Fe/Mn mole ratio of 4:1, PVA concentration of 7 %, particle size of 4 mm) could remove more than 70 % of NOR (1–20 mg/L). The NOR removal by Fe-Mn oxide filler involved adsorption and redox reactions. Notably, bioretention facilities using Fe-Mn oxide fillers have shown varying degrees of improvement in the removal of NOR and conventional pollutants compared to conventional ones. This study contributes to the application of Fe-Mn oxide filler in bioretention facilities, thus playing a crucial role in mitigating antibiotic pollution in stormwater runoff.

Synthesis and characterization of an innovative sodium alginate/polyvinyl alcohol bioartificial hydrogel for forward-osmosis desalination.

Recently, hydrogels have been widely applied as draw agents in forward osmosis (FO) desalination. This work aims to synthesize bioartificial hydrogel from a blend of sodium alginate (SA) and polyvinyl alcohol (PVA) using epichlorohydrin (ECH) as a crosslinker. Then this prepared hydrogel was applied as a draw agent with cellulose triacetate membrane in a batch (FO) cell. The effects of the PVA content in the polymer blend and the crosslinker dose on the hydrogel's swelling capacity were investigated to optimize the hydrogel's composition. Furthermore, the water flux and the reverse solute flux of the optimum SA/PVA hydrogel were evaluated in a batch (FO) unit under the effect of the hydrogel's particle size, feed solution (FS) temperature, FS concentration, and membrane orientation. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and compression strength tests were used to characterize the prepared hydrogel. Results revealed that the equilibrium swelling ratio (%) of 5228 was achieved with a hydrogel that had 25% PVA and a crosslinking ratio of 0.8. FO experiments revealed that the maximum water flux of 0.845 LMH achieved, when distilled water was used as FS, average hydrogel's particle size was 60µm, and the FS temperature was 40°C.

Sorafenib and Piperine co-loaded PLGA nanoparticles: Development, characterization, and anti-cancer activity against hepatocellular carcinoma cell line

Hepatocellular carcinoma (HCC) exhibits high mortality rates in the advanced stage (>90 %). Sorafenib (SORA) is a targeted therapy approved for the treatment of advanced HCC; however, the reported response rate to such a therapeutic is suboptimal (<3%). Piperine (PIP) is an alkaloid demonstrated to exert a direct tumoricidal activity in HCC and improve the pharmacokinetic profiles of anticancer drugs including SORA. In this study, we developed a strategy to improve efficacy outcomes in HCC using PIP as an add-on treatment to support the first-line therapy SORA using biodegradable Poly (D, L-Lactide-co-glycolide, PLGA) nanoparticles (NPs). SORA and PIP (both exhibit low aqueous solubility) were co-loaded into PLGA NPs (PNPs) and stabilized with various concentrations of polyvinyl alcohol (PVA). The SORA and PIP-loaded PNPs (SP-PNPs) were characterized using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Powder Diffraction (XRD), Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM), Release of these drugs from SP-PNPs was investigated in vitro at both physiological and acidic pH, and kinetic models were employed to assess the mechanism of drug release. The in vitro efficacy of SP-PNPs against HCC cells (HepG2) was also evaluated. FTIR and XRD analyses revealed that the drugs encapsulated in PNPs were in an amorphous state, with no observed chemical interactions among the drugs or excipients. Assessment of drug release in vitro at pH 5 and 7.4 showed that SORA and PIP loaded in PNPs with 0.5 % PVA were released in a sustained manner, unlike pure drugs, which exhibited relatively fast release. SP-PNPs with 0.5 % PVA were spherical, had an average size of 224 nm, and had a high encapsulation efficiency (SORA ∼ 82 %, PIP ∼ 79 %), as well as superior cytotoxicity compared to SORA monotherapy in vitro. These results suggest that combining PIP with SORA using PNPs may be an effective strategy for the treatment of HCC and may set the stage for a comprehensive in vivo study to evaluate the efficacy and safety of this novel formulation using a murine HCC model.

A Novel Method to Enhance the Mechanical Properties of Polyacrylonitrile Nanofiber Mats: An Experimental and Numerical Investigation.

This study addresses the challenge of enhancing the transverse mechanical properties of oriented polyacrylonitrile (PAN) nanofibers, which are known for their excellent longitudinal tensile strength, without significantly compromising their inherent porosity, which is essential for effective filtration. This study explores the effects of doping PAN nanofiber composites with varying concentrations of polyvinyl alcohol (PVA) (0.5%, 1%, and 2%), introduced into the PAN matrix via a dip-coating method. This approach ensured a random distribution of PVA within the nanofiber mat, aiming to leverage the synergistic interactions between PAN fibers and PVA to improve the composite's overall performance. This synergy is primarily manifested in the structural and functional augmentation of the PAN nanofiber mats through localized PVA agglomerations, thin films between fibers, and coatings on the fibers themselves. Comprehensive evaluation techniques were employed, including scanning electron microscopy (SEM) for morphological insights; transverse and longitudinal mechanical testing; a thermogravimetric analysis (TGA) for thermal stability; and differential scanning calorimetry (DSC) for thermal behavior analyses. Additionally, a finite element method (FEM) analysis was conducted on a numerical simulation of the composite. Using our novel method, the results demonstrated that a minimal concentration of the PVA solution effectively preserved the porosity of the PAN matrix while significantly enhancing its mechanical strength. Moreover, the numerical simulations showed strong agreement with the experimental results, validating the effectiveness of PVA doping in enhancing the mechanical properties of PAN nanofiber mats without sacrificing their functional porosity.

An innovative Fuller’s earth-based film-forming formulation for skin decontamination, through removal and entrapment of an organophosphorus compound, paraoxon-ethyl

Organophosphorus compounds (OPs), such as VX, pose a significant threat due to their neurotoxic and hazardous properties. Skin decontamination is essential to avoid irreversible effects. Fuller’s earth (FE), a phyllosilicate conventionally employed in powder form, has demonstrated decontamination capacity against OPs. The aim of this study was to develop a formulation that forms a film on the skin, with a significant OP removal capacity (>95 %) coupled with sequestration capabilities, favorable drying time and mechanical properties to allow for easy application and removal, particularly in emergency context. Various formulations were prepared using different concentrations of polyvinyl alcohol (PVA), FE and surfactants. Their removal and sequestration capacity was tested using paraoxon-ethyl (POX), a chemical that simulates the behavior of VX. Formulations with removal capacity levels surpassing 95 % were mechanically characterized and cell viability assays were performed on Normal Human Dermal Fibroblast (NHDF). The four most promising formulations were used to assess decontamination efficacy on pig ear skin explants. These formulations showed decontamination levels ranging from 84.4 ± 4.7 % to 96.5 ± 1.3 %, which is equivalent to current decontamination methods. These results suggest that this technology could be a novel and effective tool for skin decontamination following exposure to OPs.

Preparation, characterisation and in vitro anti-inflammatory activity of Baicalin microsponges

Baicalin, a flavonoid extracted from traditional Chinese medicine, Scutellaria baicalensis has significant anti-inflammatory effects. Microsponges are drug delivery systems that improve drug stability and slow the release rate. The combination of baicalin and the microsponges produced a new and stable system for its delivery, resulting in a novel formulation of baicalin. Baicalin microsponges (BM) were prepared using the quasi-emulsion solvent diffusion method. Effects of the mass ratio of the polymer (ethylcellulose) to baicalin, the concentration of the emulsifier polyvinyl alcohol (PVA), the stirring speed on the encapsulation efficiency (EE), and yield of the microsponges were investigated by combining the one-factor test and Box-Behnken design (BBD). The preparation process was standardised using 2.61:1 mass ratio of ethyl cellulose to baicalin, 2.17% concentration of PVA, with stirring at 794 rpm. Optimised BM formulations were evaluated for the parameters of EE (54.06 ± 3.02)% and yield of (70.37 ± 2.41)%, transmission electron microscopy (TEM), and in vitro cell evaluation. Results of the in vitro anti-inflammatory assay showed that baicalin microsponges-pretreated-lipopolysaccharide (LPS)-induced RAW264.7, mouse macrophages showed reduced inflammatory response, similar to that seen in baicalin-treated macrophages.

Design of Colon Specific Delivery of Sulfasalazine Loaded Nanoparticles for Inflammatory Bowel Syndrome: Application of Experimental Design

Sulfasalazine is the first line treatment for Inflammatory Bowel syndrome. Conventional formulation have poor targeting properties for colon site.Therefore designof colon specific nanoparticles (NP) is an ideal for better therapeutic outcome. The study aims to formulate and evaluate polymeric Nanoparticles loaded with Sulfasalazine to target the colon. The nanoparticles were prepared by Nano-precipitation method using pH dependent polymer and the prepared nanoparticles were evaluated for FTIR, morphology, pH, Viscosity, Entrapment efficiency, particle size and zeta potential etc. The nanoparticles were used to formulate core tablet and core tablets were coated with Eudragit S100. The tablets were evaluated for hardness, friability, thickness, weight variation and In vitro release study. Totally six formulations were developed for preliminary trial with varying concentration of polymers. From the preliminary trial, code F2batch was found to be best formulation. The F2batch was fitted to central composite design with two independent factors i.e. Concentration of Eudragit S100 (X1) and polyvinyl alcohol (X2) with four dependent variables i.e. Entrapment efficiency -Y1; Hardness- Y2; Friability-Y3 and In-vitro drug release- Y4. The formulation (code R6) was found to be the optimizedformulation. The optimized colon targeted tablets provide satisfactory release and might be suitable for colon targeting of sulfasalazine with better therapeutic effect.

Optimization of Ink Composition and 3D Printing Process to Develop Soy Protein-Based Scaffolds.

Inks based on soybean protein isolate (SPI) were developed and their formulations were optimized as a function of the ink heat treatment and the content of other biopolymers to assess the effects of protein-polysaccharides and protein-protein interactions. First, the rheological behavior of the inks was analyzed in relation to the polyvinyl alcohol (PVA) concentration employed (20, 25, and 30 wt%) and, as a result of the analysis, the ink with 25 wt% PVA was selected. Additionally, sodium alginate (SA) and gelatin (GEL) were added to the formulations to improve the viscoelastic properties of the inks and the effect of the SA or GEL concentrations (1, 2, and 3 wt%) was studied. All inks showed shear thinning behavior and self-supporting abilities. Among all the 3D printed scaffolds, those with higher SA (3 wt%) or GEL (2 and 3 wt%) content showed higher shape fidelity and were selected for further characterization. Texture profile analysis demonstrated that the scaffolds prepared with previously heat-treated inks containing 3 wt% GEL showed the highest strength. Additionally, these scaffolds showed a higher water-uptake capacity profile.

Use of creep and recovery protocol to assess the printability of fibre-reinforced 3D printed white Portland cement composites

ABSTRACT White Portland cement is an ideal choice for producing 3D printed coloured composites due to its inherent whiteness. However, the uncontrollable rheological properties limit the establishment of printed structures and thus affect the mechanical properties. In this study, the polyvinyl alcohol (PVA) and polypropylene (PP) fibres were utilised as reinforcement materials in 3D printed white Portland cement composites (WPCCs) to improve the printability and toughness by controlling creep properties, aiming to build better printed structures. Experimental results show that the addition of PVA and PP fibres effectively improve the creep properties of WPCCs, and printed structures can be well built by controlling creep properties. Specifically, the thixotropy of WPCCs with PVA and PP fibre is improved within specific content ranges of 0∼1% and 0.4∼0.8%, respectively. Compared with reference sample, the flexural strength increases by approximately 148.8% and 90.2% when the PVA and PP fibre contents reach 1.25% and 1%, respectively.

Cellulose Extraction From Green Algae, Ulva Ohnoi, and Its Application to PVA‐Based Antibacterial Composite Films Incorporated With Zinc Oxide Nanoparticles

ABSTRACTCellulose was successfully extracted from green algae (Ulva ohnoi) by chemical treatments. The contents of holocellulose and α‐cellulose significantly increased from 37.6% and 3.3% to 82.5% and 63.3%, respectively, after whole extraction treatments. The extracted cellulose (EC) was mixed to polyvinyl alcohol (PVA) to prepare EC/PVA composite films with polyethylene glycol (PEG) or glycerol (GLY) as a plasticizer. The EC/3%PVA composite film showed the highest tensile strength of 54.42 MPa because of the high PVA content. Adding GLY steeply increased the elongation of the EC/3%PVA film from 3.12% to 126.76%, but adding PEG slightly decreased to 2.63%. The EC/1%PVA/PEG composite film showed the highest visible light transmittance of 84.47%, while the addition of zinc oxide nanoparticles (ZnO‐NPs) significantly improved UV‐blocking properties. In addition, the incorporation of ZnO‐NPs on the EC/PVA‐based composite films showed excellent antibacterial activity against six Gram‐positive and Gram‐negative bacteria.