scholarly journals Preparation of a Hydrogel Nanofiber Wound Dressing

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2178
Author(s):  
Radek Jirkovec ◽  
Alzbeta Samkova ◽  
Tomas Kalous ◽  
Jiri Chaloupek ◽  
Jiri Chvojka
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Wound Dressing ◽  
Testing Procedure ◽  
Fibrous Layer ◽  
Skin Cover ◽  
Before And After ◽  
Strength And Ductility ◽  
Do So

The study addressed the production of a hydrogel nanofiber skin cover and included the fabrication of hydrogel nanofibers from a blend of polyvinyl alcohol and alginate. The resulting fibrous layer was then crosslinked with glutaraldehyde, and, after 4 h of crosslinking, although the gelling component, i.e., the alginate, crosslinked, the polyvinyl alcohol failed to do so. The experiment included the comparison of the strength and ductility of the layers before and after crosslinking. It was determined that the fibrous layer following crosslinking evinced enhanced mechanical properties, which acted to facilitate the handling of the material during its application. The subsequent testing procedure proved that the fibrous layer was not cytotoxic. The study further led to the production of a modified hydrogel nanofiber layer that combined polyvinyl alcohol with alginate and albumin. The investigation of the fibrous layers produced determined that following contact with water the polyvinyl alcohol dissolved leading to the release of the albumin accompanied by the swelling of the alginate and the formation of a hydrogel.

scholarly journals Synthesis of Nanofiber from Polyvinyl Alcohol (PVA)-Collagen Using Electrospinning Methods

2020 ◽  
Vol 21 (2) ◽  
pp. 55-65
Author(s):  
Sudirman Sudirman ◽  
Aloma Karo Karo ◽  
Sulistiyoso Giat Sukaryo ◽  
Karina Dwi Adistiana ◽  
Kiagus Dahlan
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Wound Dressing ◽  
Collagen Fiber ◽  
Tissue Formation ◽  
Collagen Concentration ◽  
Electrospinning Method ◽  
Growth Of Bacteria

Polyvinil alcohol (PVA) polymer can be used as matrix to be mixed with collagen in the subtance of primary wound dressing material to cover wound that prevents growth of bacteria and enhanced tissue formation. Collagen fiber is fragile, so important to combined with PVA to obtain better mechanical properties. The PVA-collagen fibers are prepared in aqueous solutions with PVA (10%) and collagen concentration (1% and 2%) using electrospinning method and the effect of voltage 15 kV, 19 kV, and 23 kV. Analysis of functional groups show that the presence of identical compounds produced and new functional groups are not formed. SEM data show that the effect of variation of voltage and collagen concentration on the resulting morphology of fiber. PVA-collagen 2% fibers produce continuous fibers, has a diameter 284-426 nm, thickness 0.0324-0.0483 mm and has a high percent of elongation so it can be used as a wound dressing material.

The Impact of Corrosion on the Mechanical Behavior of Bolt

2010 ◽  
Vol 168-170 ◽  
pp. 408-411
Author(s):  
Xiao Yong Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Corrosion Test ◽  
Laboratory Tests ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Rock Bolt ◽  
Before And After ◽  
The Impact ◽  
Strength And Ductility

Corrosion is a negative contributor on the structural integrity of rock bolt and leads to degradation of the mechanical properties of steel rock bolt. Exposure to chloride, seawater, salt and saltwater and deicing chemical environments influences rock bolt and weakens it. In order to evaluate the influence of corrosion and the size of the steel on the mechanical properties of rock bolt, an experimental investigation was conducted on rock bolt whose rebar is 8, 12, 16, and 18 mm diameter, and which were artificially corroded for 10, 20, 30, 45, 60, 90, and 120 days. By the simulation corrosion test of loaded and unloaded bolts in Na2SO4 solution, the relation curves of the mechanical performance with the corrosive conditions and the corrosion time are given. The mechanical performance is compared between these two types of bolts. At the same time, the influential trend of the load on the mechanical performance of the corroded bolt is analyzed. The laboratory tests suggest that corrosion duration and rebar size had a significant impact on the strength and ductility degradation of the specimens. after being corroded in Na2SO4 solution, both the ultimate bearing capacity and the maximal tensility of loaded bolt decrease far more than those of unloaded bolt, and the endurance and service life of loaded bolt will also be shortened much more severely. The tensile mechanical properties before and after corrosion indicated progressive variation and drastic drop in their values.

Study on Medical Polyvinyl Alcohol (PVA) / Polyvinyl Pyrrolidone (PVP) Hydrogel Wound Dressing

2011 ◽  
Vol 287-290 ◽  
pp. 1925-1928
Author(s):  
Shu Di Zhang ◽  
Yu Chun Zhai ◽  
Zhen Fang Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyvinyl Alcohol ◽  
Water Absorption ◽  
Human Body ◽  
Wound Dressing ◽  
Ph Value ◽  
Polyvinyl Pyrrolidone ◽  
Water Contents

Polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) hydrogel wound dressing has been fabricated using freezing-thawing method. The content of water, the rate of water absorption and pH value of hydrogel were tested, The mechanical properties and water transmissivities of hydrogels were analyzed when the PVP contents were difference. Experiments results show that the hydrogels diaphaneity is better, water contents are over 70percent; water transmissivity of hydrogels are over 100 percent, the highest value reaches to 204 percent; the pH value closes to the level of human body, the highest pH value reaches to 6.83; the tensile strength of hydrogel is 0.75 MPa when PVP content is 8 percent, reaches to the largest value; all of PVA/PVP hydrogels water transmissivities reach to 700 g·m-2·24h-1.

scholarly journals Effect of polyurethane/polyvinyl alcohol coating on mechanical properties of polyester harness cord

e-Polymers ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 38-47
Author(s):  
Kaifang Xie ◽  
Xinjun Bao ◽  
Hengshu Zhou ◽  
Bin He ◽  
Yuegang Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Polyvinyl Alcohol ◽  
Tensile Properties ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Bending Properties ◽  
Water Based ◽  
Before And After ◽  
Pet Fibers

Abstract In this article, water-based polyurethane (PU) with different concentrations and partial alcoholysis polyvinyl alcohol (PVA) were used to coat polyester (PET) harness cord in turn. The surface and mechanical properties of harness cord before and after coating were evaluated by performing the tests of dynamic contact angle, morphology observation, bending properties, tensile properties, and wearability. It was found that the surface properties of 1.5% PU-coated harness cord tended to be stable, and the mechanical properties of PU(1.5%)/PVA-coated harness cord were optimal. Compared with PVA-coated harness cord, the wearability of PU(1.5%)/PVA-coated harness cord showed a great increment up to 135.7%. This was because the PU coating effectively improved the interfacial properties between the PVA coating and the hydrophobic PET fibers and enhanced the adhesion of the PVA coating to the PET fibers.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

scholarly journals Novel Co-Cu-Based Immiscible Medium-Entropy Alloys with Promising Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 238
Author(s):  
Sujung Son ◽  
Jongun Moon ◽  
Hyeonseok Kwon ◽  
Peyman Asghari Rad ◽  
Hidemi Kato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Binary System ◽  
Design Methodology ◽  
Miscibility Gap ◽  
Face Centered Cubic ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Face Centered ◽  
Strength And Ductility ◽  
Cobalt Copper

New AlxCo50−xCu50−xMnx (x = 2.5, 10, and 15 atomic %, at%) immiscible medium-entropy alloys (IMMEAs) were designed based on the cobalt-copper binary system. Aluminum, a strong B2 phase former, was added to enhance yield strength and ultimate tensile strength, while manganese was added for additional solid solution strengthening. In this work, the microstructural evolution and mechanical properties of the designed Al-Co-Cu-Mn system are examined. The alloys exhibit phase separation into dual face-centered cubic (FCC) phases due to the miscibility gap of the cobalt-copper binary system with the formation of CoAl-rich B2 phases. The hard B2 phases significantly contribute to the strength of the alloys, whereas the dual FCC phases contribute to elongation mitigating brittle fracture. Consequently, analysis of the Al-Co-Cu-Mn B2-strengthened IMMEAs suggest that the new alloy design methodology results in a good combination of strength and ductility.

scholarly journals Fabrication of Hybrid Nanofibers from Biopolymers and Poly (Vinyl Alcohol)/Poly (ε-Caprolactone) for Wound Dressing Applications

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2104
Author(s):  
Sibusiso Alven ◽  
Blessing Atim Aderibigbe
Keyword(s):  
Mechanical Properties ◽  
Wound Healing ◽  
Vinyl Alcohol ◽  
Wound Dressing ◽  
Chronic Wounds ◽  
Cellular Adhesion ◽  
Wound Dressings ◽  
Poly Vinyl Alcohol ◽  
High Porosity ◽  
Hybrid Nanofibers

The management of chronic wounds is challenging. The factors that impede wound healing include malnutrition, diseases (such as diabetes, cancer), and bacterial infection. Most of the presently utilized wound dressing materials suffer from severe limitations, including poor antibacterial and mechanical properties. Wound dressings formulated from the combination of biopolymers and synthetic polymers (i.e., poly (vinyl alcohol) or poly (ε-caprolactone) display interesting properties, including good biocompatibility, improved biodegradation, good mechanical properties and antimicrobial effects, promote tissue regeneration, etc. Formulation of these wound dressings via electrospinning technique is cost-effective, useful for uniform and continuous nanofibers with controllable pore structure, high porosity, excellent swelling capacity, good gaseous exchange, excellent cellular adhesion, and show a good capability to provide moisture and warmth environment for the accelerated wound healing process. Based on the above-mentioned outstanding properties of nanofibers and the unique properties of hybrid wound dressings prepared from poly (vinyl alcohol) and poly (ε-caprolactone), this review reports the in vitro and in vivo outcomes of the reported hybrid nanofibers.

scholarly journals Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Przemysław Snopiński ◽  
Mariusz Król ◽  
Marek Pagáč ◽  
Jana Petrů ◽  
Jiří Hajnyš ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Heat Treatments ◽  
Electron Backscattered Diffraction ◽  
Angular Pressing ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Before And After ◽  
The Impact

AbstractThis study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material’s strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.

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