Fabrication of porous polymeric structures using a simple sonication technique for tissue engineering

2017 ◽  
Vol 37 (9) ◽  
pp. 943-951 ◽  
Author(s):  
Alan Saúl Álvarez-Suarez ◽  
Eduardo Alberto López-Maldonado ◽  
Olivia A. Graeve ◽  
Fabián Martinez-Pallares ◽  
Luis Enrique Gómez-Pineda ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Poly Vinyl Alcohol ◽  
Porous Structures ◽  
Average Pore ◽  
Ultrasonic Probe ◽  
Polymeric Scaffolds ◽  
Before And After ◽  
Water Absorption Test ◽  
Sonication Technique ◽  
Polymeric Structures

AbstractPorous polymeric scaffolds have been applied successfully in the biomedical field. This work explores the use of an ultrasonic probe to generate cavitation in a polymeric solution, thus producing pores in the polymeric scaffolds. Porous polymeric structures with average pore sizes ranging from 5 to 63 μm and porosity of 6–44% were fabricated by a process consisting of sonication, flash freezing, and lyophilization of poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), chitosan (CS) and poly(vinyl alcohol) (PVAL) solutions. Pore structure was characterized by scanning electron microscopy (SEM) and image analysis software. The infrared spectra were analyzed before and after the fabrication process to observe any change in the chemical structure of the polymers. A water absorption test indicated the susceptibility of the samples to retain water in their structure. TGA results showed that GEL experienced degradation at 225°C, CS had a decomposition peak at 280°C, the thermal decomposition of PLGA occurred at 375°C, and PVAL showed two degradation regions. The DSC analysis showed that the glass transition temperature (Tg) of GEL, CS, PLGA and PVAL occurred at 70°C, 80°C, 60°C and 70°C, respectively. The fabricated porous structures demonstrated similar physical characteristics to those found in bone and cartilage.

Novel Electro Polymerization Method to Synthesized Anti-corrosion Coated Layer on Stainless Steel Surface from (N-Benzothiazolyl Maleamic Acid) and Study its Biological Activity

2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Muna I Khalaf ◽  
Khulood A Saleh ◽  
Khalil S Khalil
Keyword(s):  
Stainless Steel ◽  
Chemical Structure ◽  
Inhibition Efficiency ◽  
Steel Plate ◽  
Polymeric Coating ◽  
Stainless Steel Surface ◽  
Plate Electrode ◽  
Before And After ◽  
Maleamic Acid ◽  
Polymerization Method

Electro polymerization of N-benzothiazolyl maleamic acid (NBM) was carried out on stainless steel plate electrode in a protic medium of monomer aqueous solution using electrochemical oxidation procedure in electrochemical cell.Spectroscopic characterization techniques were investigated to obtain information about the chemical structure of polymer. The anti-corrosion action of polymer was investigated on stainless steel by electrochemical polarization method. In addition, the effect of adding nanomaterial (TiO2, ZnO (bulk-nano)) to monomer solution on the corrosion behavior of stainless steel was investigated. The results obtained showed that the corrosion rate of S-steel increased with temperature increase from 293K to 323K and the values of inhibition efficiency by coating polymer increase with nanomaterial addition. Apparent energies of activation have been calculated for the corrosion process of S-steel in acidic medium before and after polymeric coating. Furthermore were studied the effect of the preparing polymer on some strain of bacteria.

Silica Sol-Gel Supported Nickel Nano-Catalyst for Hydrogen Production Using Microreactors

2005 ◽  
Vol 885 ◽  
Author(s):  
Krithi Shetty ◽  
Shihuai Zhao ◽  
Wei Cao ◽  
Naidu V. Seetala ◽  
Debasish Kuila
Keyword(s):  
Steam Reforming ◽  
Average Pore Size ◽  
Sol Gel ◽  
Supported Catalyst ◽  
Silica Sol ◽  
Average Pore ◽  
Steam Reforming Of Methanol ◽  
Nano Catalyst ◽  
Before And After ◽  
Reforming Reactions

ABSTRACTThe goal of this research is to investigate the activities of a non-noble nano-catalyst (Ni/SiO2) using Si-microreactors for steam reforming of methanol to produce hydrogen for fuel cells. The supported catalyst was synthesized by sol-gel method using Ni (II) salts and Si(C2H5O)4 as starting materials. EDX results indicate that the actual loading of Ni (5-6%) is lower than the intended loading of 12 %. The specific surface area of the silica sol-gel encapsulated Ni nano-catalyst is 452 m2/g with an average pore size of ∼ 3 nm. Steam reforming reactions have been carried out in a microreactor with 50 µm channels in the temperature range of 180-240 °C and atmospheric pressure. Results show 53% conversion of methanol with a selectivity of 74 % to hydrogen at 5 l/min and 200 °C. The magnetic properties of the catalysts were performed using a Vibrating Sample Magnetometer (VSM) to study the activity of the catalysts before and after the steam reforming reactions. The VSM results indicate much higher activity in the microreactor compared to macro-reactor and Ni forms non-ferromagnetic species faster in the microreactor.

scholarly journals Chitosan succinate/PVA-PEG Membrane: Preparation, Characterization and Permeation Ability Test on Creatinine

2018 ◽  
Vol 21 (2) ◽  
pp. 80-84 ◽  
Author(s):  
Retno Ariadi Lusiana ◽  
Vivi Dia Ahmad Sangkota ◽  
Sri Juari Santosa
Keyword(s):  
Tensile Strength ◽  
Water Absorption ◽  
Poly Vinyl Alcohol ◽  
Inversion Method ◽  
Ability Test ◽  
Chitosan Membrane ◽  
Water Absorption Test ◽  
Poly Ethylene ◽  
Membrane Strain ◽  
Phase Inversion Method

Evaluation character of chitosan membrane-succinate / poly vinyl alcohol-poly ethylene glycol (PVA-PEG) were prepared in acetic acid solvent through a phase inversion method has been performed. The study began with the preparation of crosslinked chitosan compounds with succinic acid, followed by preparation into membrane by combining PVA-PEG. Character analysis of the resulting material using FTIR, EDX, TGA, water absorption test, tensile strength, membrane hydrophilicity. The ability of membrane permeation was tested against creatinine. The results showed that the succinate had reacted with chitosan. Chitosan modification through cross link and polymer alloys increases tensile strength and membrane strain of 1.7-2.5 x of pure chitosan membrane. In addition, the modified membrane also has higher water absorption and hydrophilicity values than the unmodified membrane, and this implies the ability of membrane-induced creatinine permeation. Permeable permeation values were 13.8% in chitosan, 24.84% on chitosan-succinate and 25% in chitosan-succinate / PVA-PEG. Chitosan-succinate membranes have the ability to use more than 4x repeated use.

Effect of Quartz Sand Coated with Water-Treatment Residuals as Arsenic Adsorbent

2013 ◽  
Vol 663 ◽  
pp. 1064-1069 ◽  
Author(s):  
Chi Chuan Kan ◽  
Meng Wei Wan ◽  
Hui Ling Yang ◽  
Chih Chao Wu
Keyword(s):  
Water Treatment ◽  
Quartz Sand ◽  
Arsenic Concentration ◽  
Surface Characteristics ◽  
Isotherm Models ◽  
Water Treatment Residuals ◽  
Arsenic Adsorption ◽  
Average Pore ◽  
Before And After ◽  
Iron Manganese

In this study, quartz sand coated with water-treatment residuals was tested for its effectiveness as an arsenic adsorbent. The surface characteristics of the quartz sand before and after modification were analyzed. Different amounts of modified quartz sand were then tested for their adsorption capacity, using raw water with an arsenic concentration of 500 ppb. Analysis showed that the surface area and average pore diameter of the quartz sand had increased significantly after modification, as did the amounts of iron, manganese, and aluminum found as surface elements. Using both Freundlich and Langmuir isotherm models to measure the effectiveness of arsenic adsorption by the modified quartz sand, it was found that the latter model, for monolayer adsorption, was more appropriate.

Occurrence and Prevention of Changes in the Chemical Structure of Natural Rubber Tire Tread Vulcanizates during Service

1970 ◽  
Vol 43 (5) ◽  
pp. 1215-1224 ◽  
Author(s):  
J. I. Cunneen ◽  
R. M. Russell
Keyword(s):  
Chemical Structure ◽  
Main Chain ◽  
Heavy Duty ◽  
Structural Alterations ◽  
The Road ◽  
Rubber Tire ◽  
Before And After ◽  
On The Road ◽  
The Stability ◽  
Made In

Abstract The chemical structure of the tread vulcanizate of heavy-duty tires has been investigated before and after service on the road, and after testing under conditions designed to induce tread-lift. Significant changes occurred. These included a marked reduction in the concentration of polysulfide crosslinks, and an increase in the amount of monosulfide crosslinks and main chain modification. Experiments with vulcanizates made in the laboratory indicated that the structural alterations in the tires were due to thermal anaerobic reactions caused by heat build-up, and that they resulted in a deterioration in some of the physical properties of the tread vulcanizate. The rate of desulfuration of ‘model’ polysulfides has been found to depend critically upon the nature of the vulcanization recipe. These novel findings point the way to improving the stability of vulcanizates used in the treads of tires and, consequently, tire performance.

A comparison of methods for obtaining nanocellulose using acid and ionic liquid hydrolysis reactions

2019 ◽  
Vol 107 ◽  
pp. 19-23
Author(s):  
MARTA BABICKA ◽  
IZABELA RATAJCZAK ◽  
KRZYSZTOF DWIECKI
Keyword(s):  
Particle Size ◽  
Ionic Liquid ◽  
Acid Hydrolysis ◽  
Chemical Structure ◽  
Comparison Of Methods ◽  
Material Particle ◽  
Before And After ◽  
Scattering Study ◽  
Nanometric Size ◽  
Hydrolysis Reactions

A comparison of methods for obtaining nanocellulose using acid and ionic liquid hydrolysis reactions. In this study, two methods were compared, i.e. acid hydrolysis using sulphuric acid (VI) and ionic liquid hydrolysis using 1-methyl-3-butylimidazolium chloride to obtain nanocellulose from Sigmacell Cellulose Type 20. The efficiency of both processes was tested for weight loss of the material during the reaction. The study showed that much more material can be obtained using ionic liquid hydrolysis than using acid hydrolysis. A dynamic light scattering study was performed to determine material particle size before and after these processes. Particles of nanometric size were recorded only for cellulose after the reaction with an ionic liquid. In addition, Fourier transform infrared spectroscopy was performed to determine the chemical structure of the materials tested.

scholarly journals Synthesis of poly(vinyl alcohol) — hydroxyapatite composites and characterization of their bioactivity

2013 ◽  
Vol 11 (9) ◽  
pp. 1403-1411 ◽  
Author(s):  
Zuzana Balgová ◽  
Martin Palou ◽  
Jaromír Wasserbauer ◽  
Jana Kozánková
Keyword(s):  
Vinyl Alcohol ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Weight Percent ◽  
Poly Vinyl Alcohol ◽  
Aqueous Environment ◽  
Calcium Nitrate Tetrahydrate ◽  
In Vitro Bioactivity ◽  
Before And After

AbstractAbstract A series of poly(vinyl alcohol) membranes reinforced with hydroxyapatite in various weight percent — 0%, 10%, 20%, 30%, 40% and 50% were prepared. Hydroxyapatite was prepared by a sol-gel procedure using diammonium hydrogen phosphate and calcium nitrate tetrahydrate as starting materials in an alkaline aqueous environment and then mixed with a solution of poly(vinyl alcohol), which was prepared by dissolving it in water at 85°C. The different mixtures were cast in a mould and evaporated for 7 days at a temperature of 30°C to obtain 1 mm thin membranes. FTIR spectroscopy was used to identify the different functional groups in the composites. The surface morphology was examined using a scanning electron microscope. In vitro bioactivity tests in Simulated Blood Fluid were performed for up to 28 days, especially for the membrane containing 50 wt.% HA. SEM was used to characterise the surface microstructure of biocomposite membranes before and after soaking in SBF. It was observed that the formation of clusters in membranes increases with increasing amount of HA. The clusters are formed due to agglomeration and crystal growth of HA particles during drying of the membranes. The in vitro bioactivity was found to increase with soaking time of biocomposite materials in simulated blood fluid. Graphical abstract

scholarly journals Manufacturing of amber particles suitable for composite fibre melt spinning

2016 ◽  
Vol 70 (2) ◽  
pp. 51-57
Author(s):  
Inga Ļ Ļašenko ◽  
Sergejs Gaidukovs ◽  
Jūlija Rombovska
Keyword(s):  
Melt Spinning ◽  
Chemical Structure ◽  
Polyamide 6 ◽  
Polyamide Fibre ◽  
Ball Mills ◽  
Composite Fibre ◽  
Before And After ◽  
The Matrix ◽  
Average Size ◽  
Experimental Findings

Abstract Polyamide fibre containing amber particles was fabricated. The amber particles were obtained by grinding technology using planetary ball-mills. Scanning electron microscopy and granulometry testing were used to characterise the structure and the size of prepared amber particles. Fourier transform infrared spectroscopy was used to analyse the chemical structure of the amber particles. The amber particles were characterised with average size up to 3 μm. The chemical composition of amber before and after the grinding remained unchanged. The amber particles were melt-extruded using polyamide 6 as the matrix. Melt spinning processing was used to fabricate polyamide-amber filaments. Pre-oriented yarns and fully drawn yarns were obtained after hotdrawing experiments. Reported experimental findings of amber composite fibre could be important for textile applications.

Dynamics of Fibrovascular Tissue Ingrowth in Hydrogel Foams

1995 ◽  
Vol 4 (3) ◽  
pp. 275-279 ◽  
Author(s):  
M. Conley Wake ◽  
Antonios G. Mikos ◽  
Georgios Sarakinos ◽  
Joseph P. Vacanti ◽  
Robert Langer
Keyword(s):  
Void Fraction ◽  
Pore Diameter ◽  
Average Pore Diameter ◽  
Poly Vinyl Alcohol ◽  
Cell Seeding ◽  
Void Space ◽  
Average Pore ◽  
Tissue Ingrowth ◽  
Fibrovascular Tissue ◽  
Volume Average

We have investigated and quantified the degree of fibrovascular tissue ingrowth in cylindrical poly(vinyl alcohol) (PVA) foams of 12.5 mm diameter, 5 mm thickness, and 71% porosity implanted in the mesentery of rats over a period of 25 days. Fibrovascular tissue penetrated the center of PVA foams 5 days postimplantation yet the void fraction available for cell seeding was 55% and the volume average pore diameter was 190 (±39) μm. By 10 days postimplantation the void fraction had decreased to 32% and the volume average pore diameter was 121 (±20) μm. As time elapsed fibrovascular tissue continued to expand and fill the remaining pore space. At 15 days postimplantation the void space was impractical for cell seeding and continued to decrease through the remainder of the study. Our data suggest that hydrogel foams with a polydispersed pore morphology can be prevascularized with adequate space for cell seeding as the volume of tissue penetrating the foam is limited by the smaller pores in the foam structure; however, available void space for cell seeding decreases with time.

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