Prevlačenje optičkih vlakana kompozitnom prevlakom polimer-magnetni prah II. Izračunavanje debljine prevlake u zavisnosti od procesnih parametara

The paper deals with characteristics of coating materials for optical fibers together with the obtained numerical simulation results. The basic components are defined: monomod optical fiber, poly(ethylene-co-vinyl acetate) - EVA and two types of magnetic powders (BaO×6Fe2O3 and SmCo5). The paper shows influence of the process parameters on layer thickness: the diameter, diameter of original optical fiber, concentration of EVA copolymer in toluene, concentration of magnetic powders and type of magnetic powder. The calculated data have been compared with experimental results.Prikazane su karakteristike materijala korišćenih za prevlačenje optičkih vlakana, kao i rezultati numeričke simulacije. Definisane su osnovne polazne komponente: monomodno optičko vlakno, poli(etilen-ko-vinil acetat) - EVA i dve vrste magnetnog praha (barijumferit - BaO×6Fe2O3 i samarijumkobaltpet - SmCo5). Prikazan je uticaj procesnih parametara na debljinu prevlake: prečnik dizne, prečnik osnovnog optičkog vlakna koncentracija EVA u toluenu, koncentracija magnetnog praha u disperziji i vrsta magnetnog praha. Izvršena je diskusija dobijenih rezultata i poređenje sa eksperimentalnim vrednostima

Modeling of coating optical fibers with polymer-magnetic powder composite coating

A mathematical model of forming a composite coating on optical fiber was established. The model is based on existing mathematical models for coating optical fibers with polymer coating and experimentally defined rheological behavior of the investigated dispersed system. The model was developed for a dispersed system consisting of poly(ethylene-co-vinyl acetate) - EVA in a form of toluene solution and powders of magnetic materials (BaFe12O19 and SmCo5). The influence of the die diameter, diameter of the original optical fiber, concentration of EVA and magnetic powders on the thickness of composite coating was investigated. The model shows good agreement with experimental data

Investigation of the conditions of synthesis of optical fiber-magnetic powder composites

The goal of these investigations was synthesis of optical fiber-magnetic powder composites with new application possibilities like sensors, detectors etc. Parts of results of the investigation of the possibility of embedding magnetic powder of SmCo5 type in the coating of optical fiber are presented. The influence of the dispersion composition on the uniformity of composite coating was analyzed. For each investigated concentration of magnetic powder SmCo5 a composition of dispersion that produced the most uniform composite coating, for constant velocity and temperature of coating was established.Ova istraživanja usmerena su u cilju dobijanja kompozita optičko vlakno-magnetni prah sa novim mogućnostima primene - senzori, detektori i dr. Prikazan je deo rezultat ispitivanja mogućnosti ugradnje magnetnog praha tipa SmCo5 u omotač optičkog vlakna. Analiziran je uticaj sastava disperzije na Uniformnost kompozitne prevlake. Za svaku ispitanu koncentraciju magnetnog praha SmCo5 utvrđen je sastav disperzije koja omogućava formiranje najravnomernije prevlake pri konstantnoj temperaturi i brzini prevlačenja

Nanosilica/PMMA composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide-ethanol mixture

Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained nanosilica/PMMA composites. The results indicate advantageous properties of nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as nanosilica sol and nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 A degrees C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample

Transparent PMMA/silica nanocomposites containing silica nanoparticles coating under supercritical conditions

This work reports the preparation of PMMA/silica nanocomposites with high optical transparency and enhanced mechanical properties using a melt compounding method. The surface of SiO2 particles was modified with a gamma-methacryloxypropyltrimethoxy silane coupling agent in a supercritical carbon dioxide-ethanol mixture and by conventional procedure. Dispersion of silica nanoparticles in ethanol at low temperatures plays an important role in deagglomeration and dispersion of nanosilica, which leads to the optimal particle-matrix bonding in composites. The optimal mechanical and optical properties were found for composites loaded with 5 wt% silica nanoparticles treated under supercritical coating method

Preparation, characterization and mechanical properties of Bi12SiO20-PMMA composite films

This paper investigates processing and characterization of polymer composite material PMMA-Bi12SiO20 (BSO). Thin films of pure PMMA and composites with 0.5 and 1.0 wt% of Bi12SiO20 powder were made using solution casting method. Characterization of starting components and composites was performed with XRD, FTIR, Raman spectroscopy, SEM, DCS, tensile tests, nanoindentation and spectroscopic ellipsometry method in order to obtain information of their morphology, structure, thermal stability, mechanical and optical properties. Refractive index measurements using spectroscopic ellipsometry method have shown that refractive index of composites increases with the powder content. Nanoindentation and tensile tests have shown mechanical improvements with the addition of the crystal through Young's and reduced Young's modulus and hardness values. DSC analysis has shown an increase in T-g for composite with BSO

Dynamic mechanical properties of nanocomposites with poly (vinyl butyral) matrix

This work reports the preparation of SiO(2) and TiO(2)/poly (vinyl butyral) nanocomposites with enhanced dynamic mechanical properties. Silica and titania nanoparticles were introduced in the matrix as the neat powder and as colloidal sol using the melt mixing process. Composites reinforced with colloidal sol silica and titania showed higher mechanical properties than the ones reinforced with as-received particles. When sol TiO(2) particles are used, the highest increase of storage modulus of about 54% is obtained for 5 wt% loading, while for sol SiO(2), the storage modulus increases with the addition of nanosilica with the largest increase of about 99% for 7 wt% loading. In addition, nanocomposites were introduced within Kevlar/PVB composites. The addition of 5 wt% silica and titania colloidal sol lead to the remarkable increase of the storage modulus for about 98 and 65%, respectively. Largest contribution of nanoreinforcements in lowering the glass transition temperature is observed for 7 wt% loading of TiO(2) and SiO(2) colloidal sol

Synthesis, characterization and cytotoxicity of surface amino-functionalized water-dispersible multi-walled carbon nanotubes

Surface functionalization of multi-walled carbon nanotubes (MWCNTs), with amino groups via chemical modification of carboxyl groups introduced on the nanotube surface, using O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (N-HATU) and N,N-diisopropylethylamine (DIEA) is reported. The N-HATU coupling agent provides faster reaction rate and the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. The amines, 1,6-hexanediamine (HDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and 1,4-phenylenediamine (PDA) were used. The resulting materials were characterized with different techniques such as FTIR, XRD, elemental analysis, TGA, TEM, UV-vis spectroscopy and cyclic voltammetry. MWCNTs functionalized with PDA posses the best dispersibility and electron transfer properties in comparison to the others amines. Functionalized MWCNTs, at the concentrations between 1 and 50 μg ml-1, were not cytotoxic for the fibroblast L929 cell line. However, the concentrations of MWCNTs higher of 10 μg ml-1 reduced cell growth and this effect correlated positively with the degree of their uptake by L929 cells

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