scholarly journals Synthesis of Intelligent pH Indicative Films from Chitosan/Poly(vinyl alcohol)/Anthocyanin Extracted from Red Cabbage

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1088 ◽  
Author(s):  
Vo ◽  
Dang ◽  
Chen
Keyword(s):  
Tensile Strength ◽  
Vinyl Alcohol ◽  
Color Change ◽  
Sodium Tripolyphosphate ◽  
Poly Vinyl Alcohol ◽  
Ph Indicator ◽  
Red Cabbage ◽  
Cast Films ◽  
Ft Ir ◽  
Pva Hydrogel

In this study, pH indicative films were successfully synthesized from hydrogels made by blending 1% poly(vinyl alcohol) (PVA) and 1% chitosan (CS) with anthocyanin (ATH) and sodium tripolyphosphate (STPP). Particularly, ATH extracted from red cabbage was used as the pH indicator, while STPP was utilized as the cross-linking agent to provide better mechanical properties of the cast films. FT-IR spectra confirmed the existence of the ATH in the cast films. Moreover, the tensile strength, the elongation-at-break, and the swelling indices of the cast films were measured. In general, these properties of pH indicative films were profoundly influenced by the compositions of PVA/CS and the STPP dosage applied in the hydrogels. For example, the tensile strength could change from 43.27 MPa on a film cast from pure PVA hydrogel to 29.89 MPa, if 35% of the PVA hydrogel was substituted with CS. The cast films were applied as a food wrap that could be used to monitor visually the quality of the enwrapped food via the color change of the film upon the variation in pH values of the enwrapped food. In practice, a sequential change in color was successfully observed on the pH indicative films partially enwrapping the pork belly, indicating the spoilage of the meat.

scholarly journals Linear Dynamic Viscoelasticity of Dual Cross-Link Poly(Vinyl Alcohol) Hydrogel with Determined Borate Ion Concentration

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 71
Author(s):  
Takuro Taniguchi ◽  
Kenji Urayama
Keyword(s):  
Vinyl Alcohol ◽  
Ion Concentration ◽  
Poly Vinyl Alcohol ◽  
Relaxation Dynamics ◽  
Cross Link ◽  
Dynamic Viscoelasticity ◽  
Linear Dynamic ◽  
Cross Links ◽  
Pva Gel ◽  
Pva Hydrogel

We investigated the linear dynamic viscoelasticity of dual cross-link (DC) poly(vinyl alcohol) (PVA) (DC-PVA) hydrogels with permanent and transient cross-links. The concentrations of incorporated borate ions to form transient cross-links in the DC-PVA hydrogels (CBIN) were determined by the azomethine-H method. The dynamic viscoelasticity of the DC-PVA hydrogel cannot be described by a simple sum of the dynamic viscoelasticity of the PVA gel with the same permanent cross-link concentration and the PVA aqueous solution with the same borate ion concentration (CB = CBIN) as in the DC-PVA gel. The DC-PVA hydrogel exhibited a considerably higher relaxation strength, indicating that the introduction of permanent cross-links into temporary networks increases the number of viscoelastic chains with finite relaxation times. In contrast, the relaxation frequency (ωc) (given by the frequency at the maximum of loss modulus) for the DC-PVA hydrogel was slightly lower but comparable to that for a dilute PVA solution with the same CB. This signifies that the relaxation dynamics of the DC-PVA hydrogels is essentially governed by the lifetime of an interchain transient cross-link (di-diol complex of boron). The effect of permanent cross-linking on the relaxation dynamics was observed in the finite broadening of the relaxation-time distribution in the long time region.

Novel pH-Sensitive Poly(Vinyl Alcohol) Based Polyampholyte as Pervaporation Membrane

2016 ◽  
Vol 852 ◽  
pp. 979-983
Author(s):  
Ping Rui Meng ◽  
Liang Bo Li
Keyword(s):  
Aqueous Solution ◽  
Vinyl Alcohol ◽  
Water Resistance ◽  
Graft Copolymerization ◽  
Sodium Acrylate ◽  
Poly Vinyl Alcohol ◽  
Permeate Flux ◽  
Ft Ir ◽  
Ethanol Aqueous Solution ◽  
Poly Acrylamide

Sodium acrylate (NaAA) and acrylamide (AM) were grafted onto poly (vinyl alcohol) (PVA) using potassium persulfate as an initiator, Graft copolymerization namely poly (vinyl alcohol)-g-poly (acrylamide/sodium acrylate) (PVA-g-PAM/SAC). The poly (vinyl alcohol)-g-poly (vinylamine/sodium acrylate) (PVAMC) was prepraed by Hofmann rearrangement.The PVAMC homogeneous membrane was characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM).The water resistance of the PVAMC membranes is the best when pH of the PVAMC solutions was 4, at that time the numbers of-NH3+ and-COO- groups trended to be equal, so the isoelectric point was pH=4. At 90 °C the pervaporation of PVAMC composite membrane was tested and showed that the separation factor and the permeate flux were about 1001 and 1341 g/(m2·h) for 90wt% ethanol aqueous solution, and they were about 1297 and 1040 g/(m2·h) for 90wt% isopropanol aqueous solution.

scholarly journals Regulation Mechanism of Graphene Oxide on the Structure and Mechanical Properties of Bio-Based Gel-Spun Lignin/Poly (Vinyl Alcohol) Fibers

2021 ◽  
Author(s):  
Yanhong Jin ◽  
Yuanyuan Jing ◽  
Wenxin Hu ◽  
Jiaxian Lin ◽  
Yu Cheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Graphene Oxide ◽  
Young’S Modulus ◽  
Vinyl Alcohol ◽  
Young's Modulus ◽  
Lignin Content ◽  
Poly Vinyl Alcohol ◽  
Regulation Mechanism ◽  
Composite Fibers

Abstract Lignin has been used as a sustainable and eco-friendly filler in composite fibers. However, lignin aggregation occurred at high lignin content, which significantly hindered the further enhancement of fiber performance. The incorporation of graphene oxide (GO) enhanced the mechanical properties of the lignin/poly(vinyl alcohol) (PVA) fibers and affected their structure. With the GO content increasing from 0 to 0.2%, the tensile strength of 5% lignin/PVA fibers increased from 491 MPa to 631 MPa, and Young's modulus increased from 5.91 GPa to 6.61 GPa. GO reinforced 30% lignin/PVA fibers also showed the same trend. The tensile strength increased from 455 MPa to 553 MPa, and Young's modulus increased from 5.39 GPa to 7 GPa. The best mechanical performance was observed in PVA fibers containing 5% lignin and 0.2% GO, which had an average tensile strength of 631 MPa and a Young’s modulus of 6.61 GPa. The toughness values of these fibers are between 9.9-15.6 J/g, and the fibrillar and ductile fracture microstructure were observed. Structure analysis of fibers showed that GO reinforced 5% lignin/PVA fibers had higher crystallinity, and evidence of hydrogen bonding among GO, lignin, and PVA in the gel fibers was revealed. Further, water resistance and swelling behavior of composite PVA fibers were studied to further evidence the structure change of composite fibers.

scholarly journals Development of poly(vinyl alcohol)-based membranes by the response surface methodology for environmental applications

2020 ◽  
Vol 24 ◽  
pp. e5
Author(s):  
Juliana Zanol Merck ◽  
Camila Suliani Raota ◽  
Jocelei Duarte ◽  
Camila Baldasso ◽  
Janaina Da Silva Crespo ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Citric Acid ◽  
Response Surface ◽  
Acid Concentration ◽  
Vinyl Alcohol ◽  
Membrane Preparation ◽  
Poly Vinyl Alcohol ◽  
Esterification Reaction ◽  
Citric Acid Concentration ◽  
Ft Ir

The pollution of hydric sources by pharmaceuticals is an issue in many countries, particularly in Brazil. The presence of these substances causes deleterious effects on the environment and human health. One of the main sources of this contamination is domestic sewage, due to the expressive amount of medicines released in their unaltered form. Unfortunately, traditional wastewater treatment is not effective for the removal of pharmaceuticals and, for this reason, membrane technology is an attractive alternative to overcome this issue. In this regard, hydrophilic polymers, such as poly(vinyl alcohol) (PVA), are the most suitable. However, their high affinity with water causes intense swelling, leading to severe modifications in the membrane properties. In view of all these facts, the present work evaluated the swelling of PVA-based membranes, with the aim of finding the membrane preparation method that has the lowest swelling, thereby providing the most suitable characteristics for pharmaceutical removal from wastewater. The membranes were prepared by the casting of a polymeric solution, with PVA as a basis polymer, citric acid as a crosslink agent and glycerol and silver nanoparticles as performance additives. The process optimization was performed using a design of experiments with posterior analysis by the response surface methodology (RSM). The RSM assessed the effect on the membrane swelling of the factors, including citric acid concentration and the time and temperature of crosslinking. The membrane characterization was performed by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy coupled with a field emission gun (SEM-FEG) and water contact angle (WCA) measurements. Overall, the condition that showed the lowest swelling was obtained with 10% of citric acid and crosslinking for 4 h at 130 °C. Under these conditions, the membrane had a mass swelling of 42% and a dimensional swelling of 24%. Additionally, our statistical analysis revealed that the factors with the dominant effects were the citric acid concentration and the temperature of crosslinking. The FT-IR analysis suggested that the crosslinking occurred by an esterification reaction, as showed by the stretching frequencies of C=O at 1710 cm-1 and ester C-O at 1230 cm-1. Moreover, the SEM-FEG images revealed a smooth and flat surface and a dense cross section with a thickness of ~113 μm. Concerning the WCA, the angle was at ~80°, which is characteristic of hydrophilic materials. Finally, the data suggested that it is possible to optimize the membrane preparation process with adequate properties so that it can be subsequently applied to the removal of pharmaceuticals from hospital wastewater.

Characterization and comparison of properties of cryogenic conditioned CNT reinforced thermoset (epoxy) and thermoplastic (poly vinyl alcohol) composite yarns

2021 ◽  
pp. 002199832110417
Author(s):  
Wei Chen ◽  
Yifan Wang ◽  
Kun Zhang ◽  
Fujun Xu
Keyword(s):  
Tensile Strength ◽  
Vinyl Alcohol ◽  
Thermoplastic Composite ◽  
Advanced Materials ◽  
Poly Vinyl Alcohol ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Composite Yarn ◽  
Thermoset Epoxy ◽  
New Generation

Carbon nanotube (CNT) fiber/yarn reinforced composites are considered as a new generation of advanced materials for applications in aerospace and space industry. In this study, two types of CNT composite yarns were produced by twisting CNT films and infiltrating with thermoset epoxy (EP) and thermoplastic poly vinyl alcohol (PVA) resins. The tensile strength of CNT/PVA and CNT/EP composite yarn was 409.91 MPa and 206.87 MPa, much higher than that of pure CNT yarn (129.94 MPa). After mono-cryogenic condition, the mechanical and electrical properties of CNT/EP and CNT/PVA composite yarns were both enhanced due to the structure reorder of the CNT bundles and improvement of interfacial bonding. However, after 60 times cyclic-cryogenic conditions, CNT/EP composite yarn showed a ∼10% degradation of tensile strength; while CNT/PVA composite yarn exhibited 6% increment. This study provides fundamental data of the CNT reinforced thermoset and thermoplastic composite yarns for their practical applications in cryogenic environment.

Dual-Charge Nanofiber Mats Made of Chitosan(CS)/Poly(Vinyl Alcohol) (PVA) and Poly-(Acrylic Acid-Co-Maleic Acid) (PAMA)/PVA

2019 ◽  
Vol 819 ◽  
pp. 145-150
Author(s):  
Thapakorn Chareonying ◽  
Junnasir M. Sakilan ◽  
Theerasak Rojanarata ◽  
Prasopchai Patrojanasophon ◽  
Prasert Akkaramongkolporn ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Maleic Acid ◽  
Vinyl Alcohol ◽  
Electrospinning Process ◽  
Poly Vinyl Alcohol ◽  
Water Capacity ◽  
Ft Ir ◽  
Nanofiber Mats ◽  
Positively Charged ◽  
Poly Acrylic Acid

Nanofibers have been widely used for tissue engineering. Using charged polymers for the preparation of nanofibers can be useful for the loading of substances or macromolecules. Dual charge nanofiber mats are expected to be able to immobilize both positively charged and negatively charged substances in one versatile nanofiber mat. The purpose of this study was to prepare and characterize dual-charge nanofibers generated from poly (vinyl alcohol) (PVA)/poly-(acrylic acid-co-maleic acid) (PAMA) and chitosan (CS)/PVA. The polymer solutions of PAMA/PVA (1:1.63 w/w) and CS/PVA (1:2.33 w/w) were electrospun to form the nanofibers using dual-jet electrospinning process. The obtained dual-charge nanofibers were thermally crosslinked by leaving the nanofibers in the oven at 110-130 °C for 0.5, 1, 3, 5 h. The appearance of the nanofiber mat was characterized by a scanning electron microscope (SEM), and the diameter of nanofibers were determined by an image analysis software (J-micro vision®). The percentage water insolubilization and FT-IR spectra were also determined. The dual-size nanofiber mats with smooth and bead-free fibers were obtained. The diameter of the PAMA/PVA and CS/PVA fibers was 574.54 ± 142.98 nm and 225.69 ± 41.92 nm, respectively. The desirable temperature and time for the crosslink of the dual-charge nanofiber mats was 130 °C for 1 h which could provide a high insolubilization with water capacity of 93.22 ± 2.23%.

scholarly journals Mixed Amphiphilic Polymeric Nanoparticles of Chitosan, Poly(vinyl alcohol) and Poly(methyl methacrylate) for Intranasal Drug Delivery: A Preliminary In Vivo Study

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4496 ◽  
Author(s):  
Inbar Schlachet ◽  
Hen Moshe Halamish ◽  
Alejandro Sosnik
Keyword(s):  
Methyl Methacrylate ◽  
Vinyl Alcohol ◽  
Sodium Tripolyphosphate ◽  
Brain Regions ◽  
Poly Vinyl Alcohol ◽  
Drug Bioavailability ◽  
Poly Methyl Methacrylate ◽  
Target Organs ◽  
The Brain

Intranasal (i.n.) administration became an alternative strategy to bypass the blood–brain barrier and improve drug bioavailability in the brain. The main goal of this work was to preliminarily study the biodistribution of mixed amphiphilic mucoadhesive nanoparticles made of chitosan-g-poly(methyl methacrylate) and poly(vinyl alcohol)-g-poly(methyl methacrylate) and ionotropically crosslinked with sodium tripolyphosphate in the brain after intravenous (i.v.) and i.n. administration to Hsd:ICR mice. After i.v. administration, the highest nanoparticle accumulation was detected in the liver, among other peripheral organs. After i.n. administration of a 10-times smaller nanoparticle dose, the accumulation of the nanoparticles in off-target organs was much lower than after i.v. injection. In particular, the accumulation of the nanoparticles in the liver was 20 times lower than by i.v. When brains were analyzed separately, intravenously administered nanoparticles accumulated mainly in the “top” brain, reaching a maximum after 1 h. Conversely, in i.n. administration, nanoparticles were detected in the “bottom” brain and the head (maximum reached after 2 h) owing to their retention in the nasal mucosa and could serve as a reservoir from which the drug is released and transported to the brain over time. Overall, results indicate that i.n. nanoparticles reach similar brain bioavailability, though with a 10-fold smaller dose, and accumulate in off-target organs to a more limited extent and only after redistribution through the systemic circulation. At the same time, both administration routes seem to lead to differential accumulation in brain regions, and thus, they could be beneficial in the treatment of different medical conditions.

URSS/PVA/WP Composite Materials: Preparation and Performance

2014 ◽  
Vol 968 ◽  
pp. 80-83
Author(s):  
Chuan Bao Wu ◽  
Bo Qiao
Keyword(s):  
Tensile Strength ◽  
Composite Materials ◽  
Rice Straw ◽  
Hot Pressing ◽  
Vinyl Alcohol ◽  
Tensile Elongation ◽  
Environmentally Friendly ◽  
Waste Paper ◽  
Poly Vinyl Alcohol ◽  
And Performance

A novel kind of environmentally friendly composite materials containing upper part of rice straw segments (URSS), poly (vinyl alcohol) (PVA) and waste paper (WP) were prepared by hot-pressing at 140°C for 10 min. The tensile strength, tensile elongation and hardness of composites were measured. Results showed that the tensile strength and the strength at tensile break of the composites first increased and then decreased with increasing PVA content. Tensile strength was higher than the strength at tensile break at different PVA contents, indicating that URSS/PVA/WP composite materials had certain toughness. Otherwise, URSS/PVA/WP composite materials had higher tensile strength than URSS/PVA composites. The tensile strengths of them were respectively 9.25 MPa and 3.9 MPa when prepared at PVA content of 40%. The hardness of composites lay between 90 and 96. Negligible difference exists in every composite.

Wear Reduction by Functional Protein Boundary Film on Poly(Vinyl Alcohol) Hydrogel

2005 ◽  
Author(s):  
K. Nakashima ◽  
Y. Sawae ◽  
T. Murakami
Keyword(s):  
Vinyl Alcohol ◽  
Film Formation ◽  
Glass Plate ◽  
Poly Vinyl Alcohol ◽  
Functional Protein ◽  
Adsorbed Film ◽  
Adsorption Condition ◽  
Boundary Film ◽  
Joint Prostheses ◽  
Pva Hydrogel

Poly(vinyl alcohol) (PVA) hydrogel is a candidate material for artificial cartilage of joint prostheses. From previous researches [1–4] it is shown that the wear of PVA hydrogel depends on the concentration of proteins in lubricants. Therefore it is considered that the adsorbed film formation by protein of albumin or γ-globulin influences upon the wear grade of PVA hydrogel. The remaining film of proteins on the glass plate was observed in fluorescence microscope. The adsorption condition of albumin and γ-globulin was different. The adsorbed film with effective reduction of the wear showed cooperative stratification of albumin and γ-globulin, but the condition of increased the wear showed separation of albumin and γ-globulin. Consequently, to reduce the wear of PVA hydrogel, cooperative stratification layers are effective.

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