Thin Polyester Film Research Articles

Realization of a shock-tube facility to study the Richtmyer-Meshkov instability driven by a strong shock wave.

A shock-tube facility capable of generating a planar shock with the Mach number higher than 3.0 is developed for studying Richtmyer-Meshkov instability induced by a strong shock wave (referred to as strong-shock RMI). Shock enhancement is realized through the convergence of shock within a channel with the profile determined by using shock dynamics theory. The facility is designed considering the repeatability of shock generation, transition of shock profile, and effects of viscosity and flow choking. By measuring the dynamic pressure of the tube flow using pressure sensors and capturing the shock movement through the high-speed shadowing technique, the reliability and repeatability of the shock tube for generating a strong planar shock are first verified. Particular emphasis is then placed on the ability of the facility to study strong-shock RMI, for which a thin polyester film is adopted to form the initial interface separating gases of different densities. The results indicate that the shock tube is reliable for conducting strong-shock RMI experiments.

Acid and chlorine-resistant cations selective nanofiltration membranes derived from Hoffmann alkylation reaction

Conventional polyamide and polyester thin film composite membranes (TFCMs) are susceptible to harsh conditions, because the amide and ester bonds in them will degrade under extreme pH or chlorine oxidants. This work addressed this problem by preparing TFCMs through the Hoffmann alkylation reaction. Two monomers, i.e., 1,4,7,10-Tetraazacyclododecane (TAD) and 1,2,4,5-Tetrakis(bromomethyl)benzene (TBB), were designed and underwent interfacial alkylation on polyacrylonitrile substrate. The TAD-TBB TFCMs feature high positive charge, and show good repulsion (>90%) to divalent cations. Benefiting from the stability of “C-N-C” bonds in TAD-TBB network, both the permeance (13.7 L m−2 h−1 bar−1) and cation rejection (90.3%–91.4%) of the TAD-TBB TFCMs are stable after being immersed in 2 M HCl for 21 days. Meanwhile, the TAD-TBB TFCMs maintained good separation performance (permeance: 13.9 L m−2 h−1 bar−1, MgCl2 rejection: 90.5%–92.2%) after a total free chlorine exposure of 96000 ppm h (200 ppm for 480 h). This work reported the preparation of cation-selective membranes stable in harsh environments.

Low-cost digital microfluidic approach on thin and pliable polymer films

A digital microfluidic device fabricated with a thin and pliable polyester film is reported with control by a custom-made battery-powered high voltage amplification circuit. Droplet movement on the tilt or curved surface was achieved. A low-cost approach for the fabrication of digital microfluidic device was used: the electrodes on the digital microfluidic device were fabricated with conductive carbon ink screen-printed on a polyester substrate, a layer of thin polyethylene film was used to seal and insulate the electrodes, and a layer of water repellent was coated on the surface of polyethylene film to enhance the hydrophobicity. The device is transparent and pliable, with a total thickness of approximately 70 μm. The controlled droplet movement on the curved polymer surface based on electrowetting was achieved with the compact voltage amplification circuit and the corresponding control algorithm. The fabrication for the proposed digital microfluidic device is low-cost and without sophisticated microfabrication instrumentation. Furthermore, the system is portable and may have widespread point-of-care in biological and medical applications.

Investigation of the useability of polyester protective cover for PVDF-based polymer gel electrolytes

Abstract Different techniques were used to investigate the possibility of using polyester thin film as a heat-protective cover for polyvinylidene fluoride (PVDF)-gel samples, in an attempt to stop or reduce solvent loss during thermal analyses. Two experimental techniques were used for this goal; namely hot polarized optical microscopy and hot wide-angle x-ray spectroscopy (WAXs). The measurements were taken using various configurations and conditions in the experimental techniques to check the usability of the polyester as a container-protective cover when the PGE samples undergo high heating loads. The results showed a significant effect on PVDF-gel electrolytes transparency, but no morphology changes were detected. This a good indication that encourages using this type of protective film in different applications such as Li-ion batteries.

Low-pressure fiber-optic sensor by polyester Fabry-Perot cavity and its phase signal processing analysis

This manuscript presents the development of a low-pressure extrinsic Fabry-Perot fiber optic sensor based on a thin polyester film, using a phase signal analysis. The proposed interferometer is controlled by the simple contact interaction between the polymer membrane and a multimode fiber optic tip. The created cavity was uniformly stressed by applying a pressure varying from 0 to 2 psi. A finite element analysis was performed for these parameters. The stress applied to the membrane was below the yielding point. Thus, a linear study could be performed. The wavelength spectra exhibited a blue shift with a sensitivity of around 10.5 nm/psi. Although the interference spectra presented crosstalk measurements and required an initial set-point calibration, these effects were overcome by examining the spatial frequency components’ phase analysis. The sensors offered a high sensitivity, close to 3.5 rad/psi. Ultimately, this sensor is a high sensitivity and versatile alternative for low-pressure detection.

Impact of a parallel magnetic field on radiation dose beneath thin copper and aluminum foils

Purpose: The RF coils for magnetic resonance image guided radiotherapy (MRIgRT) may be constructed using thin and/or low-density conductors, along with thinner enclosure materials. This work measures the surface dose increases for lightweight conductors and enclosure materials in a magnetic field parallel to a 6 MV photon beam. Methods: Aluminum and copper foils (9–127 μm thick), as well as samples of polyimide (17 μm) and polyester (127 μm) films are positioned atop a polystyrene phantom. A parallel plate ion chamber embedded into the top of the phantom measures the surface dose in 6 MV photon beam. Measurements (% of dose at the depth of maximum dose) are performed with and without a parallel magnetic field (0.22T at magnet center). Results: In the presence of a magnetic field, the unobstructed surface dose is higher (31.9%Dmax versus 22.2%Dmax). The surface dose is found to increase linearly with thickness for thin (<25 μm) copper (0.339%Dmaxμm−1) and aluminum (0.116%Dmaxμm−1) foils. In the presence of a magnetic field the slope is lower (copper: 0.16%Dmaxμm−1, aluminum: 0.06%Dmaxμm−1). The effect of in-beam foils is reduced due to partial shielding of the surface from contaminant electrons. Copper causes a surface dose increase ≈3 times higher than aluminum of the same thickness, consistent with their relative electron density. Polyester film (127μm) increases the surface dose (to 35% Dmax with field) about as much as a gown (36% Dmax with field), while the increase with polyimide film (17μm) is less than 1% above the open field dose. Conclusions: Thin copper and aluminum conductors increase surface dose by an amount comparable to a hospital gown. Similarly, enclosure materials made of thin polyester or polyimide film increase surface dose by only a few %Dmax in excess of an unobstructed beam. Based on measurements in this study, in-beam, surface RF coils are feasible for MRIgRT systems.

Improved antifouling performance of polyester thin film nanofiber composite membranes prepared by interfacial polymerization

Membrane technology is becoming increasingly important to solve the global water scarcity problem because it allows an efficient, economic and environmental friendly treatment of water. However, the long-term use of a filtration membrane is limited by fouling, which reduces water production rates and increases energy consumption. In this paper, polyester thin film nanofiber composite (PE TFNC) membranes with improved antifouling performance were developed for wastewater treatment. The membranes were prepared by interfacial polymerization (IP) of bisphenol A (BPA) and trimesoyl chloride (TMC) on the surface of polysulfone electrospun nanofiber membranes (PSU ENMs). The antifouling properties of the membranes were improved by varying the polymerization reaction time. All membranes were characterized with scanning electron microscope (SEM), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), porometry and zeta potential measurements. Humic acid (HA) permeation tests were carried out to relate their physicochemical properties to their filtration and antifouling performance. The best PE TFNC membrane (polymerized for 15 min) was compared with polyester based thin film composite membranes prepared on other supports and polyamide based thin film composite membranes formed by IP of piperazine (PIP) and TMC in the presence of trimethylamine (TEA). The best PE TFNC membrane exhibited a permeability of 213.0 L/m2h.bar, two orders of magnitude greater than previously reported PE thin film composite membranes, a HA separation factor of 72.5% and an irreversible fouling factor of 10.2%.

Effects of plastic film in a loosed powder form of sample preparation on elemental analysis by portable X-ray fluorescence spectrometer

The aim of this research was to study the effects of plastic film types and film thickness on elemental analysis by portable X-ray fluorescence spectrometer (pXRF). Mylar polyester film with 3.6 μm and 6.0 μm thickness, and 4.0 μm Prolene thin film were used in this study. Five rock samples were prepared by loosed powder method. The pXRF analysis of each plastic films was calibrated and evaluated the method with seven reference materials. The calibrated curves of three films were strongly correlated to referenced values (R2 > 0.95) for Al, Ca, Fe, K, Mn, Si, Sr, Th, Ti, V, Y, Zn and Zr, except for Cu, Nb, Ni, P, U, V and W. The results showed that the pXRF could be used to determine some elements in rock samples and the thickness and types of the analyzed film influenced on the analysis. The element determination using each film required the developed method by calibration curve construction (linear regression of measured values obtained by the pXRF instrument against their certified values). In addition, the results after the recalibration of each film (both Prolene thin film and Mylar polyester film) agreed well.

Chlorine-resistant polyester thin film composite nanofiltration membranes prepared with β-cyclodextrin

The chlorine resistance is recognized as one of the crucial and essential properties of membranes in water treatment field. In this study, β-cyclodextrin (β-CD) with abundant hydrophilic hydroxyl groups as aqueous phase monomer and trimesoyl chloride (TMC) as organic phase monomer were utilized to fabricate the polyester thin film composite (TFC) nanofiltration (NF) membranes by interfacial polymerization (IP) method. The optimized β-CD polyester TFC membrane with 1.8 wt% β-CDs in aqueous phase was immersed in harsh chlorine environment (10000 ppm NaClO aqueous solution) up to 96 h and exhibited the steady water flux and dye rejection, manifesting the outstanding chlorine-resistant performance of β-CD polyester TFC membranes. The sodium hypochlorite cleaning experiments showed that NaClO was effective to remove the deposited and adsorbed foulants onto the β-CD polyester TFC membranes. Therefore, the superior chlorine resistance of β-CD polyester TFC nanofiltration membranes would find promising potential applications in water treatment processes.

Effective Interfacially Polymerized Polyester Solvent Resistant Nanofiltration Membrane from Bioderived Materials

AbstractUtilization of sustainable and environmentally friendly solvents for the preparation of membranes has attracted growing interest in recent years. In this work, a polyester thin film composite solvent resistant nanofiltration (SRNF) membrane is prepared by interfacial polymerization on a cellulose support. The cellulose support is prepared by nonsolvent‐induced phase separation from a dope solution containing an ionic liquid as an environmentally friendly solvent (negligible vapor pressure). The polyester film is formed via the interfacial reaction between quercetin, a plant‐derived polyphenol, and terephthaloyl chloride. Alpha‐pinene is used as a green alternative solvent to dissolve terephthaloyl chloride (TPC) while quercetin is dissolved in a 0.2 m NaOH solution. The interfacial polymerization reaction is successfully confirmed by Fourier transform infrared and X‐ray photoelectron spectroscopy while scanning electron and atomic force microscopy are used to characterize the membrane structure. The composite membrane shows an outstanding performance with a molecular weight cut‐off around 330 Da combined with a dimethylformamide (DMF) permeance up to 2.8 L m−2 bar−1 h−1. The membrane is stable in strong aprotic solvents such as DMF offering potential application in the pharmaceutical and petrochemical industries.

Polyester thin film composite nanofiltration membranes via interfacial polymerization: influence of five synthesis parameters on water permeability

Polyester thin film composite nanofiltration membranes were synthesized on the polyethersulfone (PES) support via the interfacial polymerization between triethanolamine (TEOA) and trimesoyl chloride (TMC). Water permeability measurement were conducted on 16 polyester thin film composite membranes to evaluate the influences and interactions of five synthesis parameters: TEOA concentration (X1), TMC concentration (X2), reaction time (X3), pH of aqueous phase solution (X4), and curing (X5). These parameters were varied simultaneously between two limit levels using fractional factorial design, allowing investigation of parameters with lesser samples as well as statistical analysis of results. The regression model between the response and the parameters were developed and the fitted model were tested with analysis of variance (ANOVA). The R2 for the model was 0.94 implying the predicted values were in reasonable agreement with the experimental data, confirming the high predictability of the applied model. The relative size of effects is visually demonstrated in a Pareto chart. It could be concluded that the significant effects were in the order of X2> X5> X2X5> X3> X1. This study leads up to a regression model that will allow the synthesis of polyester thin film composite membranes via interfacial polymerization with desired water permeability within the range studied.

A novel polyester composite nanofiltration membrane formed by interfacial polymerization of pentaerythritol (PE) and trimesoyl chloride (TMC)

A novel polyester thin film composite nanofiltration (NF) membrane was prepared by interfacial polymerization of pentaerythritol (PE) and trimesoyl chloride (TMC) on polyethersulfone (PES) supporting membrane. The performance of the polyester composite NF membrane was optimized by regulating the preparation parameters, including reaction time, pH of the aqueous phase solution, pentaerythritol concentration and TMC concentration. A series of characterization, including permeation experiments, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM), zeta potential analyzer and chlorine resistance experiments, were employed to study the properties of the optimized membrane. The results showed that the optimized polyester composite NF membrane exhibited very high rejection of Na2SO4 (98.1%), but the water flux is relatively low (6.1L/m2h, 0.5MPa, 25°C). The order of salt rejections is Na2SO4>MgSO4>MgCl2>NaCl, which indicated the membrane was negatively charged, just consistent with the membrane zeta potential results. After treating by NaClO solutions with different concentrations (100ppm, 500ppm, 1000ppm, 2000ppm, 3000ppm) for 48h, the results demonstrated that the polyester NF membrane had good chlorine resistance. Additionally, the polyester TFC NF membrane exhibits good long-term stability.

EFFECT OF CURING TIME ON THE PORE SIZE AND EFFECTIVE THICKNESS/POROSITY OF POLYESTER THIN FILM COMPOSITE NANOFILTRATION MEMBRANES

Polyester thin film composite nanofiltration membranes were synthesized on the polyethersulfone (PES) support via the interfacial polymerization between triethanolamine (TEOA) and trimesoyl chloride (TMC). Here we report the effect of curing time in the interfacial polymerization process on membrane properties like pore size and effective thickness/porosity. The membrane properties were determined based on the uncharged solute permeation test and the hypothetical mechanistic structure (pore size, effective thickness/porosity) was determined using Donnan steric pore flow model (DSPM). This study also provides information on the effect of curing time on water permeability. From the 2 minute point to 10 minute point, the membranes pore sizes were reduced and negligible changes to effective thickness/porosity suggest the occurrence of additional cross-linking reaction between aqueous and organic monomers.

Synthesis and characterization of polyester thin film composite membrane via interfacial polymerization: Fouling behaviour of uncharged solute

Most hydrolysis studies on biomass in Malaysia produce high amount of xylose and glucose compared to other monosaccharides and most of them are acidic. Thin film composite (TFC) membrane developed via interfacial polymerization using triethanolamine (TEOA) and trimesoyl chloride (TMC) as monomers allows separation at low pH to occur without damaging its performance. Comparative studies were carried out on membranes with and without the thin film layer formed via interfacial polymerization on the polyethersulfone (PES) support. The surfaces of the membranes were characterized by field emission scanning electronic microscopy (FESEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and hydrophilicity via contact angle measurement. In addition, the performance and uncharged solute fouling behaviour of TFC membrane were also investigated. The TFC membrane used for characterization purposes was prepared at TEOA concentration of 4 % w/v in 1 × 10-6 M sodium hydroxide solution, TMC concentration of 0.25 % w/v in pure hexane, reaction time of 45 minutes, and cured at temperature of 60 °C. Characterization results showed a huge different between the synthesized TFC membrane and the un-synthesized PES membrane in term of surface properties and morphology. Nanofiltration results indicate that the formation of thin layer on top of PES support membrane improved the separation performance compared to PES support membrane. The synthesised polyester TFC membrane have irreversible fouling of 11.02 (±5.60) % and reversible fouling of 5.59 % using water as cleaning agent.

The effect of phenol functionality on the characteristic features and performance of fully aromatic polyester thin film composite nanofiltration membranes

The functionality of phenolic monomers affects the properties and performance of the fully aromatic TFC nanofiltration membrane.

A wireless sensor powered by a flexible stack of membraneless enzymatic biofuel cells

This paper presents a novel multilevel membraneless enzymatic biofuel cell. For the first time, we introduce the use of thin polyester films as flexible electrode substrates for a Glucose/O2 microfluidic biofuel cell. More specifically, we report a proof-of-concept based on a three dimensional (3D) microfluidic chip fabricated via rapid prototyping where two T-shaped microchannels are vertically stacked one above the other. Via the integration of two in-reservoirs, only three access ports are required and an even repartition of laminar flows is ensured within each microchannel. Both channels have gold electrodes patterned on their top and bottom walls. With four anodes/four cathodes having an individual area of 25mm2, our structure is only 425μm thick. Enzymatic reactions occur via the use of glucose oxidase and hexacyanoferrate flowing in the anolyte solution whereas freely suspended laccase and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) are introduced in the catholyte stream. Under a flow rate of 150μLmin−1 and with all anodes/cathodes connected in parallel, our structure can generate a maximum net power of 12.5±0.05μW. Connected to a voltage boost converter increasing the nominal output voltage to 3.1V, we demonstrate that our proof-of-concept can already be exploited to supply electrical energy to a wireless sensor sending temperature measurements to a remote computer.

Tunable chemical release from polyester thin film by photocatalytic zinc oxide and doped LiYF4 upconverting nanoparticles.

Once manufactured or implanted, polyester release kinetics tend to be fixed with little modulation possible for optimal local chemical concentrations. Here, a typical implantable polyester was fabricated into thin films (∼50 μm thick) with additives of photocatalytic ZnO nanoparticles, lanthanide-doped LiYF4 nanoparticle upconverting nanoparticles, or a combination thereof and irradiated with either 6 mW ultraviolet (365 nm) light emitting diodes or 50 mW near-infrared (980 nm) laser diodes to induce polymer photooxidation. Irradiated polyester films with the aforementioned photoadditives had enhanced release kinetics up to 30 times more than nonirradiated, neat films with extended release times of 28 days. Near-infrared, ZnO-mediated photocatalysis had the highest light on/light off ratio release kinetics of 15.4, while doped LiYF4 upconversion nanoparticles paired with ZnO nanoparticles had the highest linear R(2) correlation of 0.98 with respect to duty cycle and release kinetics. Future applications of the technology will aim toward modulation of previously developed polymeric reagents/drugs for real-time, feedback-optimized release.

Validation of Power Linearity in Terahertz Time-Domain Spectroscopy Using a Programmable Step Attenuator

We have constructed a programmable terahertz step attenuator by stacking metallized-film attenuators (MFAs) of different transmittances. Sputter deposition of Inconel alloy on thin polyester films is used to fabricate the MFAs. Good repeatability and flatness of the step attenuator are confirmed in transmittance measurements by a terahertz time-domain spectroscopy (THz-TDS) system. A method to evaluate the linearity of the THz-TDS system is proposed by using the step attenuator over a wide dynamic range. Calibration curves are analyzed by measuring the transmittance of maltose in different concentrations, and the validity of the proposed method is discussed.

Preparation and characterization of anti-fouling β-cyclodextrin/polyester thin film nanofiltration composite membrane

Novel β-cyclodextrin (β-CD)/polyester thin film nanofiltration composite membranes were prepared via in situ interfacial polymerization of trimesoyl chloride (TMC) and triethanolamine (TEOA) in the presence of β-CD. The effects of the concentration and pendant group of β-CD on the separation, morphology and anti-fouling performance of NF composite membrane were investigated. The results show that introducing an appropriate amount of β-CD into membrane effectively improves the membrane performance. When the concentration of β-CD is 1.8% (w/v) in the aqueous phase, the water flux of NF composite membrane reaches a value which is almost two times that of the bare polyester membrane, while maintaining the rejection to Na2SO4 at a relative high level. The NF composite membrane exhibits a remarkable increase in the negative charge density and salt rejection by the incorporation of sulfated β-CD (sβ-CD) which possesses sulfonic acid groups as pendant groups instead of hydroxyls. Furthermore, the β-CD/polyester NF composite membrane also presents a significant enhancement in the anti-fouling performance. Therefore, β-CD can be considered as a potential additive to improve the property of nanofiltration composite membrane.

Improved Bonding and Conductivity of Polypyrrole on Polyester by Gaseous Plasma Treatment

AbstractA systematic study was conducted using argon, oxygen, and nitrogen plasma to improve the adhesion of polypyrrole coating to polyester (PET) fabric for improving conductivity and to understand the mechanisms involved. PET thin film was used as a reference sample. The changes in wettability, surface chemistry and morphology were studied by water contact angle, X‐ray photoelectron spectroscopy, and atomic force and scanning electron microscopy. It was found that both the highest conductivity and the strongest interfacial bonding were achieved by oxygen plasma treatment. The increase in hydrophilicity, surface functionalization, and suitable nano‐scale roughness gave improved adhesion. magnified image