Proučavanje uticaja parametara procesa teksturiranja na strukturu i svojstva teksturiranih poliesterskih pređa

As the processes of friction texturing of POY PES are insufficiently investigated, in the context of this dissertation the influence of texturing process parameters on the properties of textured PES filaments was studied under real-plant conditions, on the equipment with a short heating zone. As experimental material POY PES filament yarn was used that was textured under industrial conditions by changing heater temperature, texturing speed, D/Y ratio in texturing zone and the stretching degree. The samples of textured yarns obtained were characterized regarding the new structure obtained (crystallinity degree, degree of orientation) and properties (fineness of textured yarns, breaking strength and breaking elongation, and also yarn elasticity characteristics and yarn shrinking). The results obtained enabled determination of physical-chemical changes on yarns textured with various texturing parameters and also their impact on physical-mechanical properties of textured yarns

Analiza formiranja PVB-SiO2 nanokompozitnih vlakana pomoću elektrospining procesa

The poly (vinyl butyral)-silica (PVB-SiO2) nanofibers were obtained by the electrospinning process. The experiments were carried out with PVB solution in concentration of 10 wt.% where ethanol was used as the solvent. The silica nanoparticles were added in the solution in different contents of 1, 3 and 5 wt.% SiO2 and nanoparticles were modified with γ-aminopropyltriethoxysilane (AMEO silane). The impacts of the parameters of the electrospinning process and the silica nanoparticles on the produced PVB-SiO2 nanocomposite fibers were tested. The structures of the PVB-SiO2 nanocomposite fibers were investigated using optical microscopy and scanning electron microscopy (SEM). The morphology and distribution of the resulting nanofibers were analyzed using the software Image-Pro Plus. .Poli (vinil butiral)-silika (PVB-SiO2) nanovlakna su dobijena metodom elektrospininga. Eksperimenti su izvedeni u rastvoru 10 mas.% PVB-a u etanolu koji je korišćen kao rastvarač. Nanočestice silike su dodate sa različitim sadržajem od 1, 3 i 5 mas.% SiO2 i modifikovane γ-aminopropiltrietoksi silanom (AMEO silanom). Istražen je uticaj procesnih parametara elektrospininga na nanokompozitna vlakna PVB-SiO2. Struktura PVB-SiO2 nanokompozitnih vlakana je proučavana pomoću optičke mikroskopije i skenirajuće elektronske mikroskopije (SEM). Morfologija proizvedenih nanokompozitnih vlakana i njihova raspodela je analizirana u Image Pro Plus softveru.

Proučavanje uticaja parametara procesa teksturiranja na strukturu i svojstva teksturiranih poliesterskih pređa

As the processes of friction texturing of POY PES are insufficiently investigated, in the context of this dissertation the influence of texturing process parameters on the properties of textured PES filaments was studied under real-plant conditions, on the equipment with a short heating zone. As experimental material POY PES filament yarn was used that was textured under industrial conditions by changing heater temperature, texturing speed, D/Y ratio in texturing zone and the stretching degree. The samples of textured yarns obtained were characterized regarding the new structure obtained (crystallinity degree, degree of orientation) and properties (fineness of textured yarns, breaking strength and breaking elongation, and also yarn elasticity characteristics and yarn shrinking). The results obtained enabled determination of physical-chemical changes on yarns textured with various texturing parameters and also their impact on physical-mechanical properties of textured yarns

Improvement of mechanical properties and antibacterial activity of crosslinked electrospun chitosan/poly (ethylene oxide) nanofibers

In this study conditions for green crosslinking with citric acid of chitosan/PEO (polyethylene oxide) nanofibers were evaluated. The thermal in situ crosslinking enabled penetration of crosslinking agent into the matrix providing an improvement of antibacterial activity, thermal stability and mechanical properties of the prepared material. With an increase of temperature above 80 degrees C antibacterial activity against Staphylococcus aureus and Escherichia coil, inversely decreased. Moreover crosslinking provided prolonged controlled drug release with outstanding increase of mechanical properties observed by nanoindentation measurements. Results of the investigation indicated crosslinking as an important parameter for producing material with multifunctional characteristics suitable for drug delivery and tissue engineering

Electrospun polycaprolactone nanofibers functionalized with Achillea millefolium extract yield biomaterial with antibacterial, antioxidant and improved mechanical properties

In this study, polycaprolactone (PCL), as a biocompatible polymer was functionalized by addition of medicinal plant extract- Achillea millefolium L. (yarrow). Nanofiber mats were fabricated from PCL solutions containing dry yarrow extract in four concentrations (5%, 10%, 15%, and 20% relative to the weight of the polymer) by using blend electrospinning method. The nanofibers were characterized for their biological, mechanical and drug release behavior. In vitro release of yarrow polyphenols from the electrospun PCL nanofibers over a period of 5 days showed the release of up to 98% of the total loaded polyphenols. The released polyphenols retained its antioxidant activity, which was determined by DPPH assay. Electrospun PCL/yarrow nanofiber mats exhibited the antibacterial effect against Staphylococcus aureus, but had no effect on the growth of Pseudomonas aeruginosa. All PCL/yarrow nanofiber mats had improved mechanical properties compared to the neat PCL nanofibers, as evident by an increase in Young's modulus of elasticity (up to 5.7 times), the tensile strength (up to 5.5 times), and the strain at break (up to 1.45 times). Based on our results, yarrow-loaded PCL nanofiber mats appeared to be multi-functional biomaterials suitable for the production of catheter-coating materials, patches, or gauzes with antibacterial and antioxidant properties

Electrospun polyacrylonitrile fibers incorporated with microporous carbon for improved airborne PM2.5 filtration

Particulate matter 2.5 (PM2.5) pollutant particles have been identified as significant participants in air pollution, thus, special attention is paid to air filtration as a method of their efficient removal. A novel and simple method of producing nanofiber-based filters for efficient PM2.5 capture with multiple active components are proposed. Electrospun polyacrylonitrile (PAN) polymer was used both as a base filter material and as a precursor for producing microporous carbon nanofibers (MCNFs), which incorporated into the nanofibrous structure of the filter media. The fabricated PAN/MCNFs filters could reach removal efficiency of PM2.5 pollutant particles of up to 99% for with polluted air airflow velocity of 500 ml min−1, showing greater pollutant particle binding affinity with incorporated MCNFs. Experiments also show enhanced mechanical and thermal properties of studied air filters, with the addition of MCNFs – more than 4% and 6% increase in storage modulus and cyclization temperature in comparison to the base PAN filter, respectively. While using a facemask with inserted PAN/MCNFs filter, a reduced temperature variation in the facial region of the user was recorded – several degrees less when compared to a commonly used 3 M Aura 9320+ mask. This opens a possibility of their application in both industrial air filtering and as filters in facemask production

Preparation of MEMO silane-coated SiO2 nanoparticles under high pressure of carbon dioxide and ethanol

The objective of this study is to investigate and compare methods of nanosilica coating with γ-methacryloxypropyltrimethoxy (MEMO) silane using supercritical carbon dioxide and carbon dioxide-ethanol mixture. Characterization of grafted silane coupling agent on the nanosilica surface was performed by the infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The d50 value and particle size distribution were determined by laser particle size analyzer (PSA). The operating parameters of silanization process at 40 °C, such as the silica/silane weight ratio, the presence of ethanol, and the pressure, were found to be important for the successful coating of silica particles with minimum agglomeration. The results indicate that presence of ethanol in high-pressure carbon dioxide plays an important role in achieving successful deagglomeration of coated nanoparticles. Dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) revealed that dispersion of the silica particles in the PMMA matrix and interfacial adhesion between silica particles and polymer matrix were enhanced, when silica nanoparticles treated with silane under high pressure of carbon dioxide and ethanol were used for the nanocomposite preparation. © 2010 Elsevier B.V. All rights reserved

3D printed mucoadhesive gelatin based buccal films

The oral mucoadhesive film is a novel and attractive formulation for local and/or systemic drug delivery through the mucosal membrane of the oral cavity. Certain active pharmaceutical ingredients (API) in conventional formulations (tablets, capsules, syrups) are absorbed in the gastrointestinal tract and undergo first-pass metabolism through the liver, thereby reducing their bioavailability. This problem can be overcome by using intraoral formulations, such as mucoadhesive buccal films that disintegrate and dissolve in the oral cavity where the absorption of API occurs. In this work, the mucoadhesive films were prepared by 3D paste printing and the influence of processing parameters on film properties and the release rate of a drug was investigated. Gelatin (GA) and the blend of gelatin/polyvinylpyrrolidone (GA/PVP) were used because of their biocompatibility. Propranolol hydrochloride (PRH) was used as a model substance because it has high first-pass metabolism and is soluble in water. Film morphology and drug distribution were followed by SEM analysis. Dissolution test in simulated saliva was done to see how PRH was released from films. Mucoadhesion test revealed that the GA/PVP films with PRH have the highest adhesion force. Obtained results introduce GA/PVP as a promising material with good adhesion and rate of drug release

Analiza formiranja PVB-SiO2 nanokompozitnih vlakana pomoću elektrospining procesa

The poly (vinyl butyral)-silica (PVB-SiO2) nanofibers were obtained by the electrospinning process. The experiments were carried out with PVB solution in concentration of 10 wt.% where ethanol was used as the solvent. The silica nanoparticles were added in the solution in different contents of 1, 3 and 5 wt.% SiO2 and nanoparticles were modified with γ-aminopropyltriethoxysilane (AMEO silane). The impacts of the parameters of the electrospinning process and the silica nanoparticles on the produced PVB-SiO2 nanocomposite fibers were tested. The structures of the PVB-SiO2 nanocomposite fibers were investigated using optical microscopy and scanning electron microscopy (SEM). The morphology and distribution of the resulting nanofibers were analyzed using the software Image-Pro Plus. .Poli (vinil butiral)-silika (PVB-SiO2) nanovlakna su dobijena metodom elektrospininga. Eksperimenti su izvedeni u rastvoru 10 mas.% PVB-a u etanolu koji je korišćen kao rastvarač. Nanočestice silike su dodate sa različitim sadržajem od 1, 3 i 5 mas.% SiO2 i modifikovane γ-aminopropiltrietoksi silanom (AMEO silanom). Istražen je uticaj procesnih parametara elektrospininga na nanokompozitna vlakna PVB-SiO2. Struktura PVB-SiO2 nanokompozitnih vlakana je proučavana pomoću optičke mikroskopije i skenirajuće elektronske mikroskopije (SEM). Morfologija proizvedenih nanokompozitnih vlakana i njihova raspodela je analizirana u Image Pro Plus softveru.

BALLISTIC COMPOSITES REINFORCED WITH INORGANIC NANOTUBES OF TUNGSTEN DISULFIDE

This research considers a possibility of improving the impact and ballistic resistance of composite materials based on aramid fabric impregnated with poly (vinyl butyral), PVB, with the application of multi-layer inorganic nanotubes of tungsten disulfide (INT-WS2) as the reinforcement. Charpy impact test, ballistic shooting and knife penetration test were performed and resulted in significant improvements for composite samples with nano-reinforcement