Addition Of Polyethylene Oxide Research Articles

Polyethylene oxide-assisted dispersion of graphene nanoplatelets in poly(lactic acid) with enhanced mechanical properties and crystallization ability

Abstract Polyethylene oxide (PEO) was introduced to improve the dispersion of graphene nanoplatelets (GNPs) in poly (lactic acid) (PLA) matrix. GNPs were dispersed into PEO aqueous solution and freeze-dried to form PEO/GNPs masterbatch, followed by melt-mixed with PLA to prepare the nanocomposites. Three grades of PEO with different molecular weights were evaluated. It is found that adding very low loading of PEO (1 wt%) enhances the dispersion of GNPs in PLA matrix, resulting in remarkable improvement in elongation at break of PLA/GNPs without obviously sacrificing its modulus and tensile strength. Meanwhile, PEO reveals a synergistic effect with GNPs in promoting PLA crystallization. Moreover, GNPs enhances significantly the thermal stability of PLA, while further addition of PEO does not apparent compromise this effect. In addition, PEO with low molecular weight presents the best effect in improving the properties of PLA/GNPs nanocomposites.

Doxycycline release and antibacterial activity from PMMA/PEO electrospun fiber mats.

Objective:To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen.Methodology:PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis.Results:The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans.Conclusion:The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.

A Study on Mechanical and Thermal Properties of PLA/PEO Blends

Poly(lactic) acid (PLA) is recognized as one of the polymers with most potential in biodegradable packaging industries. However, PLA is too brittle to be used as thin films. To increase the flexibility of PLA, 1, 3, and 5 wt% of polyethylene oxide (PEO) having 100,000 Mw were added into PLA respectively. The blends were compounded and were extruded using a kneader and a twin-screw extruder. The mechanical and thermal properties of PLA blends were analyzed to prove the increase of ductility. In addition, hydrophilic properties, morphologies, and crystallization behaviors of PLA based films were investigated. The addition of PEO into PLA increased the elongation at break, Izod impact strength, hydrophilicity, and the degree of crystallinity, as well as decreased the glass transition temperature (Tg), melting temperature (Tm), cold crystallization temperature (Tcc), and tensile strength of PLA. Significantly, the elongation at break was increased by 4 times at 5 wt% PEO loading, while the tensile strength was decreased by 17% only. PLA based films were greatly increased in ductility by blending with PEO.

Use of Zymomonas mobilis immobilized in doped calcium alginate threads for ethanol production

Zymomonas mobilis immobilized in doped calcium alginate (Ca-alginate) threads was successfully employed for the production of ethanol in immobilized cell reactors operated with both vertical and horizontal flow. Polyethylene oxide (PEO) as a dopant for Ca-alginate threads was used to increase thread porosity. The influence of the direction of the flow into the reactor and the use of a dopant on the effectiveness of microbe immobilized Ca-alginate threads to produce ethanol was studied and results were compared to the widely used 2% Ca-alginate beads. Threads were able to obtain a similar ethanol yield to beads achieving 90.7% in vertical and 88% in horizontal flow reactors, while beads obtained 91% and 74.7%, respectively. The addition of PEO decreased the lag phase of the threads in both the horizontal and vertical flow reactors compared to a Ca-alginate standard over a 24 h period. The horizontal flow reactor's ethanol yield increased from 10.5% to 41.2% with the addition of PEO while the vertical flow reactor's ethanol yield increased from 15.5% to 69.6%. Additionally, doping with PEO lead to higher ethanol yield. This study demonstrates the use of threads for immobilization of microbes and the effectiveness of PEO as a dopant.

Use of polyethylene oxide to improve flotation of fine molybdenite

Flotation tests using different size fractions of molybdenite with 50 ppm of Diesel oil and 25 ppm of MIBC, carried out in 0.01 M NaCl solutions and seawater, showed much lower floatability of the −10 μm size fraction. The flotation of this finest size fraction was very much improved with the use of polyethylene oxide (PEO). The tests revealed that the improvement resulted from aggregation of fine molybdenite particles by Diesel oil-PEO emulsion. The flotation in seawater was good only in the pH range from 7 to 9 and it was strongly depressed around pH 10–11. While addition of PEO could improve flotation in the good flotation range over pH 7–9, it was not efficient in the depression range caused by precipitating magnesium hydroxy-complexes/magnesium hydroxide.

Optimization of Chitosan-Gelatin Nanofibers Production: Investigating the Effect of Solution Properties and Working Parameters on Fibers Diameter

Electrospinning of chitosan-gelatin, using organic solvents, have already been reported. This study was designed to fabricate, characterize, and optimize electrospun chitosan-gelatin nanofibrous membranes using acetic acid as a more safe alternative aqueous solvent. Series of 90/10, 80/20, 70/30, 60/40, and 50/50 ratios of chitosan and gelatin were prepared using aqueous acetic acid as solvent. Blend solutions were electrospun after adding polyethylene oxide (PEO) to facilitate the electrospinning process. The effects of solution properties as well as the operating parameters on the architecture of the electrospun chitosan-gelatin nanofibers were investigated through evaluation of the electrical conductivity, viscosity, morphology, Fourier transform infrared spectroscopy (FTIR), mechanical properties, and hydrophilicity. Uniform beadless nanofibrous hydrophilic mats were fabricated with average fiber diameters from 229.79 ± 41.45 to 308.66 ± 50.03 nm. Concentration was the main parameter among all solution properties in controlling nanofiber diameter. The fiber diameters decreased with increasing the voltage, decreasing the feed rate, and increasing the needle to collector distance up to a certain amount. The interactions between the components of the blend solutions were confirmed by FTIR spectra. The Young’s moduli of all chitosan-gelatin blend nanofibers were higher than the chitosan nanofibers and increased significantly after cross-linking (P < 0.05). Chitosan-gelatin blends with different ratios of each biopolymer can be electrospun using acetic acid as an aqueous solvent and addition of PEO to yield hydrophilic membranes with uniform and beadless nanofibers. The architectural similarity of the nanofibrous chitosan-gelatin mats to natural ECM makes them great candidates for different biomedical applications.

Structure and Sound Absorption Properties of Spiral Vane Electrospun PVA/PEO Nanofiber Membranes

Noise pollution has become one of the four major pollution issues in the world and has drawn much attention recently. Controlling the sound source and using sound-absorbing materials reasonably is considered an effective way to reduce noise. Due to the high porosity and specific surface area, nanofibers membrane is widely used in the field of the sound absorption. Polyvinyl alcohol (PVA) and Polyethylene oxide (PEO) are both water-soluble polymers with good film-forming properties that can be mixed in any proportion. In this paper, nanofiber membranes were prepared by spiral vane electrospinning with different contents of PVA and PEO. The nanofibers membranes were characterized by Fourier Transform-Infrared (FT-IR), X-ray diffraction (XRD), 3D-M, and scanning electron microscopy (SEM). The sound absorption property of nanofibers membranes and the compositions (nanofiber membranes and needle punched non-woven fabric) were tested with an impedance tube. The results demonstrate that the addition of PEO changed the morphological characteristics and construct of PVA, sound absorption properties had undergone great changes.

Highly compact CsPbBr3 perovskite film decorated by PEO for light-emitting diodes

Inorganic perovskite light-emitting diodes (PeLEDs) with full coverage and compact films were realized by doping a certain amount of PEO into perovskite emitting layer. The additive PEO (Polyethylene oxide) can not only improve the coverage of films by physically filling the pin-holes of crystal boundaries but also act as a protective layer to passivate the films, which successfully reduce the rate of non-radiative recombination, and enhance photoluminescence quantum yield (PLQY) of the CsPbBr3 films. In addition, PEO can also decrease the surface roughness of the perovskite films. As a result, the addition of PEO can improve the transport capability of carriers in PeLEDs. By optimizing the concentration of PEO, a maximum external quantum efficiency (EQE) of 0.26% and brightness of 1432 cd/m2 were achieved, which is significantly improved compared with previous work. The results presented in this paper shows that the additive PEO in perovskite precursor solution paves a new way for the application in PeLEDs.

Experimental study of the diffusion-controlled corrosion of copper in the bottom of a jet stirred reactor

Abstract Jet stirred tank reactors are usually preferred to mechanically stirred tank reactors in the case of high pressure stirred tank reactors in order to avoid the mechanical problems inherent with mechanically agitated reactors. Owing to the impact force exercised by the fluid jet on the tank bottom, the tank bottom is subjected to severe corrosion. The aim of the present work is to address this problem using an accelerated system which simulates natural diffusion-controlled corrosion of metals. Diffusion-controlled corrosion of a fixed copper disc, at the bottom of a cylindrical tank, under a single phase forced jet flow of acidified dichromate solution was investigated. Variables studied were: physical properties of the solution, solution velocity through different diameters of jet nozzle, distance between the jet outlet nozzle and the copper disc surface; and the effect of using a drag reducing polymer. An overall correlation was obtained: Sh = 0.579 Sc 0.33 Re 0.975 (h/d) 0.049 valid for 850 < Sc < 1322, 1852 < Re < 5000 and 0.3 < h/d < 1.2. Addition of polyethylene oxide as a drag reducing polymer was found to diminish the rate of corrosion under single phase forced jet flow by an amount depending on the operation conditions.

Melt Extrusion of High-Dose Co-Amorphous Drug-Drug Combinations : Theme: Formulation and Manufacturing of Solid Dosage Forms Guest Editors: Tony Zhou and Tonglei Li.

Many future drug products will be based on innovative manufacturing solutions, which will increase the need for a thorough understanding of the interplay between drug material properties and processability. In this study, hot melt extrusion of a drug-drug mixture with minimal amount of polymeric excipient was investigated. Using indomethacin-cimetidine as a model drug-drug system, processability of physical mixtures with and without 5% (w/w) of polyethylene oxide (PEO) were studied using Differential Scanning Calorimetry (DSC) and Small Amplitude Oscillatory Shear (SAOS) rheometry. Extrudates containing a co-amorphous glass solution were produced and the solid-state composition of these was studied with DSC. Rheological analysis indicated that the studied systems display viscosities higher than expected for small molecule melts and addition of PEO decreased the viscosity of the melt. Extrudates of indomethacin-cimetidine alone displayed amorphous-amorphous phase separation after 4weeks of storage, whereas no phase separation was observed during the 16week storage of the indomethacin-cimetidine extrudates containing 5% (w/w) PEO. Melt extrusion of co-amorphous extrudates with low amounts of polymer was found to be a feasible manufacturing technique. Addition of 5% (w/w) polymer reduced melt viscosity and prevented phase separation.

5,10,15,20-Tetrakis (4-carboxyphenyl) porphin-conjugated poly(l-lactic) acid/polyethylene oxide nanofiber membranes for photodynamic therapy

In this work, a poly(l-lactic) acid (PLLA)/polyethylene oxide (PEO) nanofiber membrane was prepared by electrospinning as a carrier for the photosensitizer 5,10,15,20-tetrakis (4-carboxyphenyl) porphin (TCPP) to study the effects of singlet oxygen (1O2) on tumor cells. Scanning electron microscopy and confocal laser scanning microscopy images showed that the fiber surface was smooth and that TCPP was evenly dispersed in the nanofibers. TCPP, PLLA, and PEO were mixed with nanofibers without the formation of new chemical bonds, as shown by Fourier transform infrared spectroscopy. The addition of PEO improved the hydrophilicity of the nanofibers, making the contact angle of the PLLA nanofiber membrane change from 93.3° to near 0° and resulting in good cell compatibility. The sustained release experiment showed that when the amount of TCPP was 3%, the cumulative release concentration after 72h was close to saturation in the test system. Electron spin resonance spectroscopy confirmed that TCPP produced 1O2 at light irradiation (532nm). The results of in vitro cell experiments showed that TCPP@PLLA/PEO nanofiber membranes did not affect the normal growth of HeLa cells but had cytotoxic effects on cancer cells under light irradiation.

Synthesis of soy protein–lignin nanofibers by solution electrospinning

Nanofibers were produced by electrospinning aqueous alkaline solutions containing different mass ratios of soy protein and lignin in the presence of poly(ethylene glycol) coadjutant, all of which presented shear thinning behavior. SEM revealed that the addition of polyethylene oxide as a coadjutant indeed facilitated the formation of defect-free fibers whose diameter increased with lignin concentration, in the range between ≈124 and ≈400nm. Favorable interactions between lignin and soy protein were identified from data provided by differential scanning calorimetry. In addition, an increased hydrogen bonding and the loss of secondary structure of the proteins as the lignin concentration increased were observed from the disappearance of amide II (∼1500cm−1) and III (∼1400–1200cm−1) bands and a red shift of amide I band in the FT-IR spectrum. The unfolding of the protein contributed to a better interaction with lignin macromolecules, which further improved the electrospinning process. It is concluded that mixtures of lignin and soy proteins, two major renewable resources with interesting chemical features, are suitable for the development of composite sub-micron fibers.

폴리락틱산, 폴리카프로락톤, 폴리에틸렌 옥사이드 삼성분계 블렌드의 형태학적 변화와 이들이 의료용 스캐폴더의 기계적 특성에 미치는 영향

Ternary blends of poly(L-lactic acid) (PLLA), poly(<TEX>${\varepsilon}$</TEX>-caprolactone) (PCL) and polyethylene oxide (PEO) were produced with different concentrations of components via melt blending. By leaching the PEO from the samples by water, porous materials were obtained with potential application for bio scaffolds. Sample porosity was evaluated by calculating the ratio of porous scaffold density (<TEX>${\rho}^*$</TEX>) to the non-porous material density (<TEX>${\rho}_s$</TEX>). Highest porosity (51.42%) was related to the samples containing 50 wt%. of PEO. Scanning electron microscopy (SEM) studies showed the best porosity resulted by decreasing PLLA/PCL ratio at constant concentration of PEO. Crystallization behavior of the ternary blend samples was studied using differential scanning calorimetry (DSC). Results revealed that the crystallinity of PLLA was improved by addition of PEO and PCL to the samples. The porosity plays a key role in governing the compression properties. Mechanical properties are presented by Gibson-Ashby model.

Abrasive slurry jet micro-machining of holes in brittle and ductile materials

This paper investigated the effects of elasticity and viscosity, induced by a dilute high-molecular-weight polymer solution, on the shape, depth, and diameter of micro-holes drilled in borosilicate glass and in plates of 6061-T6 aluminum alloy, 110 copper, and 316 stainless steel using low-pressure abrasive slurry jet micro-machining (ASJM). Holes were machined using aqueous jets with 1wt% 10μm Al2O3 particles. The 180μm sapphire orifice produced a 140μm diameter jet at pressures of 4 and 7MPa. When the jet contained 50wppm of dissolved 8 million molecular weight polyethylene oxide (PEO), the blind holes in glass were approximately 20% narrower and 30% shallower than holes drilled without the polymer, using the same abrasive concentration and pressure. The addition of PEO led to hole cross-sectional profiles that had a sharper edge at the glass surface and were more V-shaped compared with the U-shape of the holes produced without PEO. Hole symmetry in glass was maintained over depths ranging from about 80–900μm by ensuring that the jets were aligned perpendicularly to within 0.2°. The changes in shape and size were brought about by normal stresses generated by the polymer. Jets containing this dissolved polymer were observed to oscillate laterally and non-periodically, with an amplitude reaching a value of 20μm. For the first time, symmetric ASJM through-holes were drilled in a 3-mm-thick borosilicate glass plate without chipping around the exit edge.The depth of symmetric blind holes in metals was restricted to approximately 150μm for jets with and without PEO. At greater depths, the holes became highly asymmetric, eroding in a specific direction to create a sub-surface slot. The asymmetry appeared to be caused by the extreme sensitivity of ductile materials to jet alignment. This sensitivity also caused the holes in metals to be less circular when PEO was included, apparently caused by the random jet oscillations induced by the polymer. Under identical conditions, hole depths increased in the order: borosilicate glass>6061-T6 aluminum>110 copper>316 stainless steel. The edges of the holes in glass could be made sharper by machining through a sacrificial layer of glass or epoxy.

Preparation and properties of low friction silicon carbide ceramic seals by pore creation

Low friction silicon carbide (SiC) ceramic seals were prepared by combining liquid phase sintering (LPS) with pore creation, the effects of polyethylene oxide (PEO) as pore former on the sintering and mechanical properties, microstructure, and friction properties of LPS–SiC ceramic seals were investigated. The PEO firstly forms cross-linking aggregates with loose structure in SiC granules, which uniformly creates macropores on the surface and inside of LPS–SiC ceramic seals during the sintering. The addition of PEO decreases the sintering and mechanical properties of LPS–SiC ceramic seals obviously, while significantly reduces the dry friction coefficient of LPS–SiC ceramic seals. When the PEO content increases from 0 to 15 wt-%, the dry friction coefficient drops from 0·403 to 0·126. The pore creation of PEO improves the friction performances of SiC ceramic seals in sliding wear applications.

Preparation and properties of monomer casting nylon-6/PEO blend prepared via in situ polymerization

A series of MC nylon-6/ polyethylene oxide (PEO) blends were prepared via in situ polymerization. It was found that addition of PEO delayed the polymerization process of caprolactam. The apparent activation energy and pre-exponential factor increased, indicating that the polymerization reaction became difficult with increasing PEO content. The stress–strain curves of the blends presented strain hardening behavior and increasing elastic deformation stress plateau at low PEO content. Nonisothermal DSC and XRD tests indicated that addition of PEO led to a decrease of the crystallization ability of the nylon-6 matrix by reducing crystal grain size and crystallinity, whereas the crystallization ability of the PEO phase was improved. No co-crystal formed between the two phases. PEO with low content only existed as amorphous state, while with increasing PEO content, PEO can crystallize gradually, forming interfibrillar segregation first, and then forming interspherilute segregation of the blend independently. By addition of PEO, the fracture surface of the blend became rough, displaying character of tough fracture. The interface between nylon-6 phase and PEO phase was diffused, and the nylon-6 matrix around the PEO particles presented fibrous structure, indicating the good compatibility between them. The toughening mechanism of the blend corresponded to the crazing-shear banding mechanism. POLYM. ENG. SCI., 55:589–597, 2015. © 2014 Society of Plastics Engineers

Reducing the entrainment of clay minerals in flotation using tap and saline water

High gangue entrainment is a major problem in fine particle flotation. In this study, the entrainment of kaolinite Q38 in flotation was examined in tap and saline water. High molecular weight polyethylene oxide (PEO) was used to reduce the entrainment of kaolinite Q38 by enlarging the size of kaolinite particles in flotation. It was found that PEO reduced the entrainment significantly in flotation using tap water, but in saline water, the effect of PEO was less pronounced. The aggregation behaviour of kaolinite Q38 particles in the absence and presence of PEO and its effect on the entrainment of kaolinite Q38 were studied by the in-situ measurement of flocs and the size of enlarged particles, settling tests and the measurement of froth stability in flotation. It is interesting to find that PEO did flocculate kaolinite Q38 particles and enlarge their sizes in flotation despite high agitation. However, the reduction of the entrainment of kaolinite Q38 in flotation was dependent on the type of flocs formed and froth stability which can be modified by electrolytes in water and a high addition of PEO.

Silica-based monoliths for enzyme catalyzed reactions in microfluidic systems with an emphasis on glucose 6-phosphate dehydrogenase and cellulase

An efficient on-chip enzyme immobilized monolith microreactor for glucose 6-phosphate dehydrogenase and its extension to cellulase catalyzed reactions is reported. The monoliths were fabricated using the sol–gel technique, where two different silica precursors were investigated, tetraethoxysilane (TEOS) and ethylene glycol modified silane (EGMS) by determining the activity and aging of the enzymes in the gels. Subsequently catalytic reactions were conducted in continuous flow microreactors and the performance of the system was evaluated by applying various flow rates (5, 10, 15, 20μl/min). The addition of polyethylene oxide (PEO) reduced shrinkage of the gels during a period of 4days after gel preparation suggesting a strengthened gel skeleton leading to a reduced channeling within the porous structure. In the microfluidic systems, the highest conversion rates achieved were 20.0% and 28.8% at a flow rate of 5μl/min with TEOS–PEO and EGMS–PEO gels. Continuous reaction exhibited better yield than batch-wise operation using same volume/enzyme ratios which can be attributed to favorable enzyme substrate affinities. However, increase in the flow rate resulted in reduced conversion rates due to lower residence times. Consequently, the applied technique not only provided shorter preparation times but also sustained the stability of immobilized enzymes.

Complex Formation of PEO and Lignin in Prehydrolysis Liquor and its Enhancing Effect on Lignin Removal

Hemicelluloses dissolved in the pre-hydrolysis liquor (PHL) of kraft-based dissolving pulping processes can potentially be used to produce high value-added products such as fuel ethanol and xylitol. However, the isolation of lignin in PHL is a problem that remains unsolved and obstructs the utilization of those parts of hemicelluloses. Based on the principle of lignin isolation by acidification, the feasibility of using polyethylene oxide (PEO) to enhance the removal of lignin from PHL was tested in this work. The formation of lignin/PEO complexes was confirmed by means of turbidity, particle size, Fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). The removal rate is affected by lignin content, chemical oxygen demand (COD), and decolorizing, and the results show that sulfuric acid acidification or PEO flocculation alone do not have an obvious effect on lignin removal from PHL. However, a much higher removal rate, compared to 2.81% (only acidification at pH 2) and 1.2% (only PEO on original PHL), of 22.75% is obtained by the sequential process of acidification and addition of PEO (pH 2 and PEO 350 mg/L in PHL).

Alginate–Polyethylene Oxide Blend Nanofibers and the Role of the Carrier Polymer in Electrospinning

We present here a systematic investigation to understand why aqueous sodium alginate can only be electrospun into fibers through a blend with another polymer; specifically, polyethylene oxide (PEO). We seek to examine and understand the role of PEO as the “carrier polymer”. The addition of PEO favorably reduces electrical conductivity and surface tension of the alginate solution, aiding in fiber formation. While PEO has the ability to coordinate through its ether group (−COC−) with metal cation like the sodium cation of sodium alginate, we demonstrate in this study using PEO as well as polyvinyl alcohol (PVA) that coordination may have little effect on electrospinnability. More importantly, we show that PEO as carrier polymer provides molecular entanglement that is required for electrospinning. Since the selected carrier polymer provides the necessary entanglement, this carrier polymer must be electrospinnable, entangled and of a high molecular weight (more than 600 kDa for PEO). On the basis of these req...