Test Liquids Research Articles

Study on ε-CL-20 Coated with a Wax/F2311 Double-Layer Composite Structure

In order to reduce the mechanical sensitivity of ε-CL-20, wax and fluororubber polymers were used as coating materials and desensitizers to coat ε-CL-20 by the water suspension method. Through molecular dynamics calculations, fluorine rubber F2311, which had a good combination with ε-CL-20, was selected as the coating material and then ε-CL-20-based composite particles with double-layer structure were prepared. The contact angles of water, glycerin and diiodomethane as the testing liquids on the surface of F2311 and wax were measured by a contact angle measuring instrument, and the thermodynamic parameters of ε-CL-20/F2311 and the ε-CL-20/wax interface were calculated. ε-CL-20 before and after coating was characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and the mechanical sensitivity analytical method. The results showed that F2311/wax had uniformly passivated on the surface of ε-CL-20, forming a dense and uniform protective film, and the CL-20 crystal form did not change after coating. The double-layer composite structure effectively reduces the sensitivity of ε-CL-20 and improves the thermal stability of ε-CL-20.

Droplet evaporation of water and fuel jets in low and high temperature subsonic crossflows

Water and Jet A fuel were injected into low and high temperature crossflows of 65 °C and 425 °C, respectively, at a fixed crossflow pressure of 100 kPa, a liquid jet to gaseous crossflow momentum flux ratio of 7.5, and a crossflow Mach number of 0.175. Liquid jet injection temperature was also varied between 20 °C and 90 °C. The orifice had a diameter of 1 mm and a length of 20 mm. Visualization of the spray primary breakup processes was achieved using high-speed imaging. Droplet characteristics were measured at cross-sectional planes 300 mm, 400 mm, and 500 mm downstream of the orifice using a 2-component phase Doppler particle anemometry system. Results discussed included the variation of liquid volume flux, droplet size, and droplet velocities with increasing distance downstream of the injector. Analysis of the results revealed distinct changes in local and global droplet characteristics for both test liquids when injected into the high temperature crossflow compared to the low temperature crossflow. These changes, including increases in measured droplet size, were more significant at the bottom of the spray plume, especially for Jet A, due to the preferential heat-up and evaporation of droplets based on size and liquid thermal properties. For Jet A droplets smaller than 5 μm evaporated completely, leaving behind larger droplets that resisted evaporation. Increasing jet injection temperature was observed to reduce droplet size at a fixed crossflow velocity by reducing liquid surface tension which enhanced atomization. Higher liquid jet injection temperatures also resulted in increased droplet evaporation that initiated closer to the orifice exit.

Surface Properties of Plasma-Activated Chitosan Foils

Thin films of chitosan are often deposited on various surfaces to provide them with antiseptic properties. In the presented research, chitosan foils were obtained using two methods and treated with nitrogen plasma. The obtained materials were characterized by measuring the wettability of the test liquids, and the apparent surface free energy was calculated using the Tadmor equilibrium contact angles. The surface topography was characterized using optical profilometry and SEM. On the other hand, the effect of plasma on surface groups was investigated using the FTIR-ATR technique. Plasma activation of the surface increases the polarity of the surface. This is observed in the changed surface roughness and the share of functional groups on the surface.

Design and fabrication of Open-ended Co-axial probe for complex permittivity measurement of liquids using CST Microwave Studio

An Open-ended co-axial probe technique is widely used for measuring the complex permittivity of material under test (MUT) over a broad range of radio and microwave frequencies. Dimension, structure and material of the co-axial probe vary with the measurement range of frequency and the magnitudes of the properties of the MUT. Therefore, it is required to customize the probes depending on the type of the material to be investigated and on the range of frequency of measurement. A co-axial probe, to measure the complex permittivity of the liquids in the frequency range 10 MHz to 3 GHz, was simulated and tested for simulated test liquids, using CST Microwave Studio software. A real probe, of same design as simulated probe, was also fabricated. Complex permittivity measurements of some test liquids were carried out using Vector Network Analyzer (VNA) and the real probe. Varying degree of agreement between theoretical and experimental complex permittivity spectra in the different frequency segments was observed. Study suggested that the open ended co-axial probe of required dimension and structure can be designed and tested through simulation.

Evaluation of polyphenylene sulfide by surface thermodynamics approaches: Comparison with common polymers

AbstractPoly(phenylene sulfide) (PPS) is an advanced thermoplastic and widely used in industrial applications requiring high performance. Research on improving the surface properties of PPS is still ongoing and a detailed surface free energy (SFE) knowledge of this polymer is necessary for its applications related to surface wettability. In this study, wettability characteristics of PPS were evaluated by SFE calculations. For this purpose, the apparent contact angles of nine different test liquids having various surface tensions were measured on the PPS surface by the sessile drop method. After that, the dispersive and polar components of SFE were calculated using geometric (Owens and Wendt's method) and harmonic (Wu's method) mean approaches. The Lifshitz‐van der Waals, acidic and basic components of SFE were calculated using van Oss‐Chaudhury‐Good method. Additionally, the surface tension values of PPS were also determined by equation of state, Zisman's critical surface tension and Fowkes' approaches. In the present study, the effects of calculation methods and selected liquid pairs on SFE parameters were systematically investigated. It was found that selected liquid pairs and calculation methods affected the SFE considerably. The reasons for this were examined and the SFE components of PPS was compared with some common polymers for better evaluation.

A Method for Measuring the Surface Free Energy of Topical Semi-solid Dosage Forms.

Our aim was to determine the surface free energy (SFE) of semi-solid dosage forms (SSDFs) by establishing a reproducible method for measuring the contact angle of liquids to SSDFs. Four SSDFs were used: petrolatum, an oil/water (O/W) and a water/oil (W/O) cream, and an alcohol-based gel. The SSDFs were evenly spread on a glass slide, and the change in contact angle over time was measured by dropping water, glycerol, diiodomethane and n-hexadecane as the test liquids. Depending on the combination of test liquid and SSDF, the contact angle was either constant or decreased in an exponential manner. Contact angles may have decreased in an exponential manner because the reaction between the test liquid and the SSDF altered the interfacial tension between the two phases and changed the surface tension of the test liquid and the SFE of the SSDF. The contact angle of the test liquid to the SSDF could be determined reproducibly using the initial contact angle immediately after dropping the liquid on the SSDF as the contact angle before reaction. Using the obtained contact angles and the Owens-Wendt-Rabel-Kaelble equation, we calculated the SFE and its component for the SSDFs tested and found that the results reflect the physicochemical properties of SSDFs. Furthermore, the work of adhesion (WA) of the SSDF to Yucatan micropig skin was calculated using the SFE for the SSDFs. Interestingly, the WA values for all SSDFs tested were comparable.

Fundamental characteristics of secondary drops produced by early splash during single-drop impingement onto a thick liquid film

Basic features of early-splash droplets produced during single-drop impact onto a quiescent liquid film were explored experimentally using water and three aqueous solutions of glycerol at different concentrations as the test liquids. It was found that the time from the contact of primary drop with a liquid film is a crucial parameter in determining the size, ejection velocity, and ejection angle of secondary drops. It was also shown that the time period for the early splash to occur, the total number of secondary drops, and the number of secondary drops produced per unit time are dependent primarily on the impact Weber number. From the experimental data accumulated in this work, dimensionless correlations were developed for these quantities. These correlations can be used to calculate various quantities such as the total mass, total surface area, and total kinetic energy of the secondary drops. As a typical example, the total mass of the secondary drops was calculated to explore its dependence on the Weber and Ohnesorge numbers.

Experimental investigation of structural, wetting, mechanical and Tribological properties of TiZrN thin films deposited by magnetron sputtering

-TiZrN thin films were deposited on Si (100) wafers and XC100 steel substrates by reactive R.f. magnetron sputtering using titanium and zirconium targets in an Ar-N2 mixture atmosphere to evaluate the effect of varying Zr content (0 to 22.2 at.%), on the film structure, surface wettability, hardness and wear resistance. The presence of different phases such as TiN, ZrN, and ZrO2 were confirmed by XRD analysis. Results showed that, the lattice parameter and film thickness increased while the crystallite size and average roughness decreased with increasing Zr content. Total surface energy between the film surface and testing liquids decreased with the addition of Zr. TiZrN film containing 18.3 at.% of Zr showed the lowest surface energy of 38.7 mN/m, indicating its hydrophobicity. The nanoindentation measurements, friction and wear tests showed that the TiZrN thin film containing 18.3 at.% of Zr had the best tribo-mechanical performance. The TiZrN (18.3 at.% Zr) film exhibited the lowest friction coefficient (0.31), and the lowest wear rate (6.65 × 10−5 mm3/Nm), which corresponds to the highest H/E ∼ 0.139, and H3/E2 ∼ 0.49 GPa ratios. The improvement in the tribo-mechanical properties is attributed to the solid solution strengthening due to the incorporation of Zr atoms in TiN system, which results in the highest hardness of 25 GPa for TiZrN (18.3 at.% Zr) film.

Design of Bridge Type C-Band Planar RF Sensor for Detection of Solute Concentration Level in Water

In this paper, a planar Micro-strip-based bridge topology CSRR is proposed for the detection of various solute concentrations in water sample. The designed bridge topology CSRR (B-CSRR) sensors resonates at 5.18 GHz with a Q-factor of 170, which exhibits a fractional sensitivity (10.17%). To avoid the contamination of test liquids, use of the thin Teflon layer is incorporated on top of the sensor region. The numerical analysis of the sensors for various scenarios including the sensor loaded with several lossy samples are carried out and accordingly shift in resonant frequency is recorded. The optimized design topology helps to attain better electric field confinement at the resonant frequency, which eventually leads to improved dielectric sensitivity. In the next part, an equivalent circuit of the proposed sensor is developed using the Advanced Design System (ADS) software. Afterwards, the designed sensor is fabricated on 0.8mm thick Taconic TLY-5 substrate ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\varepsilon }_{r}$ </tex-math></inline-formula> = 2.2). Finally, the measurement of B-CSRR sensor is carried out for different solute concentration in pure water, which is in present scenario are salt and detergent concentration, respectively. The developed sensor is found to be quite sensitive which produces a substantial change in the measured insertion loss even for small variation in solute concentration. For instance, a typical 2% variation in detergent, and salt concentration leads to nearly 1.5 dB, and 2.0 dB, change in measured S21.

Droplet deformation in secondary breakup: Transformation from a sphere to a disk-like structure

Deformation of a droplet from an initial spherical shape to a disk-like structure is common during its secondary breakup. Characterizing this initial deformation is important to develop accurate secondary breakup models. In the present study, the initial droplet deformation until initiation time (where the droplet attains a disk-like structure) was investigated by experiments with a variety of test liquids offering wide ranges of surface tension (0.022–0.71 N/m), viscosity (0.86–3.63 mPa⋅s), and density (788–6900 kg/m3). The test liquids included molten metals along with classical water-like liquids. To characterize the initial droplet deformation until the initiation time, the droplet’s displacement, relative velocity, deformation, and drag coefficient (CD) were measured. A non-dimensional parameter named the displacement–relative velocity–deformation (DVD) parameter was introduced and a mathematical expression for its temporal evolution, which could be useful for validating simulation results, was obtained. The temporal evolution of the DVD parameter and the droplet’s displacement, relative velocity, and deformation (in non-dimensional forms) for molten metals were observed to be significantly different from those for the other liquids at similar Weber numbers. A correlation for the non-dimensional droplet deformation at the initiation time is also presented by studying the relationship between an instantaneous Weber number defined at the initiation time (Weini) and the corresponding conventional Weber number (We). It is observed that the temporal evolution of CD until the initiation time for ∼30<We<∼70 (where dual-bag and sheet-thinning breakup modes are observed) is significantly different in comparison to that for ∼10<We<∼30 (where bag and bag-stamen breakup modes are observed).

Collision of water drops with a thin cylinder

The collision of water drops with a thin cylinder is studied. The droplet flight trajectory and the cylinder axis are mutually perpendicular. In the experiments, the drop diameter is 3 mm, and the diameter of horizontal stainless-steel cylinders is 0.4 and 0.8 mm. The drops are formed by a liquid slowly pumped through a vertical stainless-steel capillary with an outer diameter of 0.8 mm, from which droplets are periodically separated under the action of gravity. The droplet velocity before collision is defined by the distance between the capillary cut and the target (cylinder); in experiments, this distance is approximately 5, 10, and 20 mm. The drop velocities before the impact are estimated in the range of 0.2–0.5 m/s. The collision process is monitored by high-speed video recording methods with a frame rate of 240 and 960 Hz. The test liquids are water. Experiments and numerical simulation show that, depending on the drop impact height (droplets velocity) different scenarios of a drop collision with a thin cylinder are possible: a short-term recoil of a drop from an obstacle, a drop flowing around a cylindrical obstacle while maintaining the continuity of the drop, the breakup of a drop into two secondary drops, one of which can continue flight and the other one is captured by the cylinder, or both secondary droplets continue to fly, and the drop can be also captured by the cylinder, until the impact of the next drop(s) forces the accumulated drop to detach from the cylinder. Numerical modeling satisfactorily reproduces the phenomena observed in the experiment.

Dimensionless analysis on liquid–liquid two-phase flow patterns in a numbered-up microfluidic device

Flow patterns of six liquid–liquid systems in a numbered-up microfluidic set-up were studied in this work. Chloroform-water, butyl acetate-water, ethyl acetate-water, kerosene-water, butanol-water and octanol–water were chosen as test liquids. Three distinct flow regimes were observed in the parallelized microfluidic device: slug flow, droplet flow and parallel flow. A uniform flow distribution was achieved in the scaled-out microfluidic device for all observed flow regimes. Flow non-uniformity was determined based on both the volumetric flow rate and slug size/droplet size/interface position for each microchannel. The two-phase interface's position relative to the microchannel walls was considered a criterion for flow non-uniformity measurement in parallel flow. A comprehensive dimensionless analysis was also performed to determine which dimensionless numbers are appropriate for presenting universal flow maps. Re-0.31We0.41, We0.07Ca0.31, Re0.07Ca0.41, Ca0.5Oh-0.14, We0.25Oh0.31 and Re0.5Oh0.82 were identified as the suitable combinations of dimensionless numbers for proposing generalized flow pattern maps for the numbered-up set-up. For the slug and droplet flow regimes, slug and droplet length and velocity were also investigated.

Lossy mode resonance fiber-optic sensors based on niobium pentoxide thin film

In this work, we fabricated and investigated lossy mode resonance (LMR) based fiber-optic refractometers, using a niobium pentoxide coated optical fiber as a sensitive element. In order to do that, thin Nb2O5 films were deposited on the surface of chemically thinned optical fibers by metalorganic chemical vapor deposition (MOCVD). The sensitivities of the first transverse electric (TE) and transverse magnetic (TM) LMRs to the surrounding medium refractive index (SMRI) were measured and compared. Aqueous solutions of glucose and sodium chloride were used as test liquids. The sensor sensitivity to a change in the SMRI enhanced with an increase in the dissolved substance concentration and was greater for glucose solution. The maximum response of the 1-st TE and TM LMRs was 6580 and 6120 nm per refractive index unity (RIU), respectively.

ОЦІНКА ПОВЕРХНЕВОЇ ЕНЕРГІЇ ТВЕРДИХ ТІЛ З ВИКОРИСТАННЯМ ДВОКОМПОНЕНТНИХ СУМІШЕЙ ПРОБНИХ РІДИН

The design processes of composite materials require considering the surface energy of the phases. The choice of a series of test fluids to determine surface energy in the framework of the Zisman and Owens-Wendt models sometimes causes difficulties in the interaction of these fluids – dissolution or swelling of the substrate. The minimum number of test fluids is two, but more is used to increase accuracy. The use of mixed solvents allows to increase the number of experimental points, as well as to more accurately adjust the polarity of the medium, which is essential in determining the surface energy of substances that are unstable to the action of many solvents. The paper considered the possibility of using a mixture of a pair of test liquids that do not interact with the material and factors that may limit the accuracy of the determination. Also, on the example of stearic acid illustrates the process of determining surface energy by this method. Polypropylene and polycarbonate were chosen to determine the surface energy in the Owens-Wendt model. Test liquids used included water, ethylene glycol, dimethyl sulfoxide, ethanol, cyclohexane, glycerol and tetrahydrofuran. As a result, the use of a mixed solvent to determine the surface energy of polymers can increase the accuracy of the method by increasing the number of experimental points on the Owens-Wendt graph. Increase of the experimental points area, however, is limited to the points of individual solvents of the mixture, and the uncovered part of the graph needs to be corrected to reduce the error. It is shown that the use of only mixed solvents is inefficient due to the restriction of the zone of variability by the area between the coordinates of the individual solvents of the mixture. It has been shown that when determining the surface energy of materials that are not resistant to solvents, the accuracy can be increased by using mixed solvents, but this requires balancing the measurement range.

Theoretical Considerations of Photonic Crystal Fiber with All Uniform-Sized Air Holes for Liquid Sensing

A novel liquid-infiltrated photonic crystal fiber model applicable in liquid sensing for different test liquids—water, ethanol and benzene—has been proposed. One core hole and three air hole rings have been designed and a full vector finite element method has been used for numerical investigation to give the best results in terms of relative sensitivity, confinement loss, power fraction, dispersion, effective area, nonlinear coefficient, numerical aperture and V-Parameter. Specially, the assessed relative sensitivities of the proposed fiber with water, ethanol and benzene are 94.26%, 95.82% and 99.58%, respectively, and low confinement losses of 1.52 × 10−11 dB/m with water, 1.21 × 10−12 dB/m with ethanol and 6.01 × 10−16 dB/m with benzene, at 1.0 μm operating wavelength. This novel PCF design is considered simple and can be easily fabricated for practical use, and the assessed waveguide properties has determined the potential applicability in real liquid sensing applications.

Impact of Macrodiols on the Morphological Behavior of H12MDI/HDO-Based Polyurethane Elastomer.

In this study, we evaluated the morphological behavior of polyurethane elastomers (PUEs) by modifying the soft segment chain length. This was achieved by increasing the soft segment molecular weight (Mn = 400–4000 gmol−1). In this regard, polycaprolactone diol (PCL) was selected as the soft segment, and 4,4′-cyclohexamethylene diisocyanate (H12MDI) and 1,6-hexanediol (HDO) were chosen as the hard segments. The films were prepared by curing polymer on Teflon surfaces. Fourier transform infrared spectroscopy (FTIR) was utilized for functional group identification in the prepared elastomers. FTIR peaks indicated the disappearance of −NCO and −OH groups and the formation of urethane (NHCOO) groups. The morphological behavior of the synthesized polymer samples was also elucidated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The AFM and SEM results indicated that the extent of microphase separation was enhanced by an increase in the molecular weight of PCL. The phase separation and degree of crystallinity of the soft and hard segments were described using X-ray diffraction (XRD). It was observed that the degree of crystallinity of the synthesized polymers increased with an increase in the soft segment’s chain length. To evaluate hydrophilicity/hydrophobicity, the contact angle was measured. A gradual increase in the contact angle with distilled water and diiodomethane (38.6°–54.9°) test liquids was observed. Moreover, the decrease in surface energy (46.95–24.45 mN/m) was also found to be inconsistent by increasing the molecular weight of polyols.

On the Ejection of Filaments of Polymer Solutions Triggered by a Micrometer-Scale Mixing Mechanism.

Polymer filaments constitute precursor materials of so-called fiber mats, ubiquitous structures across cutting-edge technological fields. Thus, approaches that contribute to large-scale production of fibers are desired from an industrial perspective. Here, we use a robust liquid atomization device operated at relatively high flow rates, ~20 mL/min, as facilitating technology for production of multiple polymer filaments. The method relies on a turbulent, energetically efficient micro-mixing mechanism taking place in the interior of the device. The micro-mixing is triggered by radial implosion of a gas current into a liquid feeding tube, thus resulting in breakup of the liquid surface. We used poly(ethylene oxide) solutions of varying concentrations as test liquids to study their fragmentation and ejection dynamics employing ultra-high speed imaging equipment. Taking an energy cascade approach, a scaling law for filament diameter was proposed based on gas pressure, liquid flow rate and viscosity. We find that a filament dimensionless diameter, , scales as a non-dimensional liquid flow rate to the . The study aims to elucidate the underlying physics of liquid ejection for further applications in material production.

Characterizing bulk liquids with zero-group-velocity Lamb modes

In this work we study the coupled response of zero-group-velocity (ZGV) modes and test liquids. In particular, we assess the viability of exploiting the spatiotemporal constraint of ZGV modes to derive techniques for non-contact, non-invasive liquid characterization to support process optimization. The results demonstrate that the ZGV resonance behaves like a baffled piston source that couples into standing waves in the test liquid. Moreover the particle displacement associated with the liquid resonance extends over macroscopic length scales (∼cm). The resonance frequencies are governed by the acoustic properties and depth, h, of the test liquid. Therefore, the test liquid sound speed, cL , can be determined by analysing the spectral content of the system response. While the technique provides an accurate measure of sound speed, the morphology of immiscible mixtures (e.g. buoyancy separated or emulsion) affects the variation in sound speed with composition. In this case, it is necessary to know the mixture morphology in order to utilize the sound speed as a proxy for composition. The technology is applicable to any thin-walled (mm–cm) structure (pipe, tank, etc) commonly utilized for liquid handling. As a result, the measurement is broadly applicable to many industrial settings that require convenient and accurate methods to determine liquid composition in support of process evaluation and optimization.

Evaluation of the damaging effect of crop protection formulations on high density polyethylene using the Full Notch Creep Test

Four typical high-density polyethylene container materials were used to investigate damage or stress cracking behavior in contact with model liquids for crop protection products. These model liquids are established in German regulations for the approval of dangerous goods containers and consist of typical admixtures used for crop protection products but without biological active ingredients. This study is performed with the standardized method of Full Notch Creep Test, adapting the media temperature to 40 °C according to the usual conditions where these test liquids are applied. The two model liquids differ into a water-based solution and a composition based on different organic solvents which are absorbed by the material up to significant levels. Therefore, extensive sorption measurements are performed. The fracture surfaces obtained are analyzed in detail not only by light microscopy, but also by laser scanning microscopy as well as scanning electron microscopy. Influence of pre-saturation and applied stress are addressed by respective systematic series of experiments.

A new liquid density measurement method based on elastic spring stretching

A simple method is described for measuring liquid density based on stretching of the spring and equilibrium of weight and elastic force. The method involves placing a container with liquid under test on the spring causing a stretch of the spring that is directly proportional to the weight of the liquid. With this technique, the liquid density can be determined without measuring its mass and volume, and it should help students comprehend the concept of density more easily. The design of the measuring setup in this study is made using tools and materials that are simple and easy to obtain, such as spring, ruler, and small plastic or metallic container (tube). Two liquids used to test the measuring method were ethanol and glycerol. A test showed that the density of the test liquids at room temperature could be measured with the relative uncertainty of 3%, hence the reliability of the described method was confirmed.