Contact Angle Measurements: an Alternative Approach Towards Understanding the Mechanism of Increased Drug Dissolution from Ethylcellulose Tablets Containing Surfactant and Exploring the Relationship Between Their Contact Angles and Dissolution Behaviors

2018 ◽  
Vol 19 (4) ◽  
pp. 1582-1591 ◽  
Author(s):  
Tiaotiao Liu ◽  
Jingqiang Hao ◽  
Baixue Yang ◽  
Beibei Hu ◽  
Zhixiang Cui ◽  
...  
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Drug Dissolution ◽  
Angle Measurements ◽  
Alternative Approach ◽  
Contact Angle Measurements ◽  
The Relationship

Empirical Formulae in Correlating Droplet Shape and Contact Angle

2016 ◽  
Vol 69 (4) ◽  
pp. 431 ◽  
Author(s):  
Ten It Wong ◽  
Hao Wang ◽  
Fuke Wang ◽  
Sau Leng Sin ◽  
Cheng Gen Quan ◽  
...  
Keyword(s):  
Contact Angle ◽  
Empirical Formula ◽  
Contact Angles ◽  
Shape Deformation ◽  
Direct Identification ◽  
Simple Method ◽  
Droplet Shape ◽  
Spherical Dome ◽  
Angle Measurements ◽  
Contact Angle Measurements

In contact angle measurements, direct identification of the contact angles from images taken from a goniometer suffers from errors caused by optical scatterings. Contact angles can be more accurately identified by the height and width of the droplet. Spherical dome is a simple model used to correlate the contact angles to the droplet shape; however, it features intrinsic errors caused by gravity-induced shape deformation. This paper demonstrates a simple method of obtaining an empirical formula, determined from experiments, to correct the gravity-induced error in the spherical dome model for contact angle calculations. A series of contact angles, heights, and surface contact widths are simultaneously collected for a large amount of samples, and the contact angles are also calculated using the spherical dome model. The experimental data are compared with those obtained from the spherical dome model to acquire an empirical formula for contact angles. Compared with the spherical dome model, the empirical formula can reduce the average errors of the contact angle from –16.3 % to 0.18 %. Furthermore, the same method can be used to correct the gravity errors in the spherical dome for the volume (calculated by height and width), height (calculated by contact angle and volume), and width (calculated by contact angle and volume), and the spherical dome errors can be reduced from –20.9 %, 24.6 %, and –4.8 % to 2 %, –0.13 %, and –0.6 %, respectively. Our method is generic and applicable for all kinds of solvent and substrates, and the derived empirical formulae can be directly used for water droplets on any substrate.

Measurements of the Contact Angles for Various Fluids Which Are Widely Used in the Oilfields to Improve Oil Recovery

2018 ◽  
Author(s):  
M. Elsharafi ◽  
K. Vidal ◽  
R. Thomas
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Rock Face ◽  
Angle Measurements ◽  
Contact Angle Measurements

Contact angle measurements are important to determine surface and interfacial tension between solids and fluids. A ‘water-wet’ condition on the rock face is necessary in order to extract oil. In this research, the objectives are to determine the wettability (water-wet or oil-wet), analyze how different brine concentrations will affect the wettability, and study the effect of the temperature on the dynamic contact angle measurements. This will be carried out by using the Cahn Dynamic Contact Angle. Analyzer DCA 315 to measure the contact angle between different fluids such as surfactant, alkaline, and mineral oil. This instrument is also used to measure the surface properties such as surface tension, contact angle, and interfacial tension of solid and liquid samples by using the Wilhelmy technique. The work used different surfactant and oil mixed with different alkaline concentrations. Varying alkaline concentrations from 20ml to 1ml were used, whilst keeping the surfactant concentration constant at 50ml.. It was observed that contact angle measurements and surface tension increase with increased alkaline concentrations. Therefore, we can deduce that they are directly proportional. We noticed that changing certain values on the software affected our results. It was found that after calculating the density and inputting it into the CAHN software, more accurate readings for the surface tension were obtained. We anticipate that the surfactant and alkaline can change the surface tension of the solid surface. In our research, surfactant is desirable as it maintains a high surface tension even when alkaline percentage is increased.

Degradation of Hydrophobic Surface Coatings Under Water Exposure

2018 ◽  
Author(s):  
Matthew A. Trapuzzano ◽  
Rasim Guldiken ◽  
Andrés Tejada-Martínez ◽  
Nathan B. Crane
Keyword(s):  
Contact Angle ◽  
Material Selection ◽  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Water Exposure ◽  
Angle Measurements ◽  
Degradation Rates ◽  
Contact Angle Measurements ◽  
Receding Contact

Many important processes depend on the wetting of liquids on surfaces. Wetting is commonly controlled through material selection, coatings, and/or surface texture, however these means are sensitive to environmental conditions. Some “hydrophobic” fluoropolymer coatings are sensitive to extended water exposure as evidenced by declining contact angles and increasing contact angle hysteresis. Understanding degradation of these coatings is critical to processes that employ them. To accomplish this, contact angle measurements were taken before, during, and after slides coated with FluoroSyl 3750 or Cytop were submerged in water, or vibrated while covered in water. Both methods demonstrated similar changes in advancing contact angle though vibration increased degradation rates significantly. However, it does not simply accelerate the process as different trends are apparent in receding contact angles. The FluoroSyl 3750 showed no clear degradation under either condition. Surface profilometry did not detect any surface morphology differences that might cause contact angle change.

Contact angles and hysteresis, with some reference to flotation research

1977 ◽  
Vol 30 (1) ◽  
pp. 205 ◽  
Author(s):  
IW Wark
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Gas Phase ◽  
Water Vapour ◽  
Relative Motion ◽  
Solid Surface ◽  
Contact Angles ◽  
Russian School ◽  
Angle Measurements ◽  
Contact Angle Measurements

A technique used in flotation research for contact angle measurements is recommended for wider use. The effect of one aspect of surface roughness on the relative motion of fluid/solid systems is discussed. The function of the water vapour present in the gas phase adjacent to the line of triple contact is examined. A claim of the Russian school of surface chemists is questioned, namely, that a discrete film of water on the solid surface invariably dominates both hysteresis and contact angle.

Surface Dipoles Influence the Wettability of Terminally Fluorinated Organic Films

1998 ◽  
Vol 546 ◽  
Author(s):  
Ramon Colorado ◽  
Michael Graupe ◽  
Mitsuru Takenaga ◽  
Thomas Koini ◽  
T. Randall Lee
Keyword(s):  
Contact Angle ◽  
Organic Thin Films ◽  
Dipole Interaction ◽  
Contact Angles ◽  
Aprotic Solvents ◽  
Angle Measurements ◽  
Infrared Reflection ◽  
Contact Angle Measurements ◽  
Assembled Monolayers ◽  
High Degree

AbstractThe correlation of differences in the wettabilities of partially fluorinated self-assembled monolayers (SAMs) to changes in the chemical structure and composition of the films was explored by contact angle goniometry and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). SAMs of simple alkanethiols (CH3(CH2)nSH with n = 9-15) and their CF3-terminated analogs (CF3(CH2)nSH with n = 9-15) were prepared by adsorption from solution onto evaporated gold. Advancing contact angles of hexadecane were measured on both the terminally fluorinated surfaces and the hydrocarbon surfaces. These data were compared to those obtained using a series of polar aprotic contacting liquids. As expected, the contact angles of hexadecane were higher on the CF3-terminated SAMs than on the CH3-terminated SAMs. The contact angles of the polar aprotic solvents, however, were measurably lower on the CF3- terminated SAMs than on the CH3-terminated SAMs. These observations were rationalized on the basis that the introduction of the CF3 terminal groups yields oriented surface dipoles that interact with the dipoles of the polar contacting liquids. Further support for this model was provided by the observation of an inverse parity (“odd-even”) effect in the wettabilities of the polar aprotic solvents on the CF3-terminated surfaces. Analysis by PM-IRRAS revealed that both types of films consist of predominately trans-extended alkyl chains with relatively few gauche defects in a densely packed arrangement. The high degree of order is consistent with the detection of the parity effect, where small changes in the orientation of the tail groups can be sensed by contact angle measurements only in highly ordered organic thin films. The significance of the dipole-oriented dipole interaction in describing interfacial wettabilities is discussed.

Contact Angle Measurements of Wetting In Pristine and Ion Implanted High Modulus Benzene Derived Graphite Fibers

1984 ◽  
Vol 40 ◽  
Author(s):  
O. C. de Hodgins ◽  
M. S. Dresselhaus ◽  
D. Uhlmann
Keyword(s):  
Contact Angle ◽  
Carbon Fibers ◽  
Structural Disorder ◽  
Contact Angles ◽  
X Ray Diffraction ◽  
Three Solutions ◽  
X Ray ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Graphite Fibers

AbstractMeasurements are reported of the contact angles of benzene-derived carbon fibers with de-ionized water, aminopropyltriethoxy silane and du Pont 5878 polyimide solutions. Both pristine fibers and fibers implanted with 5×1012 cm-2 and 1×1015 cm-2 fluences of 31p ions were investigated. Such implantation was observed to decrease the contact angle in all three solutions. The ion implantation had no significant effect on tensile strength, but did result in increased structural disorder (as reflected in the width of the main wide angle X-ray diffraction peak) and increased surface roughness. The increased disorder and roughness are believed to be principally responsible for the observed change in wetting angle.

Characterization of a Ceramic Powder Surface by Contact Angle Measurements and Infrared Spectroscopy

2012 ◽  
Vol 507 ◽  
pp. 233-238 ◽  
Author(s):  
Bram Neirinck ◽  
Dimitri Soccol ◽  
Jan Fransaer ◽  
Omer Van der Biest ◽  
Jef Vleugels
Keyword(s):  
Contact Angle ◽  
Infrared Spectroscopy ◽  
Surface Chemistry ◽  
Suspended Particle ◽  
Ceramic Powder ◽  
Contact Angles ◽  
Alumina Powder ◽  
Surface Groups ◽  
Angle Measurements ◽  
Contact Angle Measurements

The surface chemistry of a suspended particle greatly affects it behavior during electrophoretic deposition. The type and amount of surface groups determines whether the particles can be charged by interaction with the solvent. Furthermore, it is suspected that the surface chemistry plays a prominent role in the mechanisms governing the actual deposition of the particles. In the present work the surface chemistry of as-received and surface modified alumina powder is characterized by means of contact angle measurements and Diffuse Reflectance Infrared Fourier Transform spectroscopy. The wetting is measured using a modified Washburn method which yields quantitative contact angle values. The acid-base and dispersive surface energy components are calculated from these values using the surface tension component theory. Infrared spectroscopy was used to compare the surface groups of the treated and untreated powders and confirm the trends in surface properties as calculated from the contact angles.

Dynamic Cycling Contact Angle Measurements: Study of Advancing and Receding Contact Angles

2001 ◽  
Vol 243 (1) ◽  
pp. 208-218 ◽  
Author(s):  
C.N.C. Lam ◽  
R.H.Y. Ko ◽  
L.M.Y. Yu ◽  
A. Ng ◽  
D. Li ◽  
...  
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Receding Contact ◽  
Dynamic Cycling

scholarly journals PAPER STRAWS: AN INVESTIGATION INTO SURFACE MODIFICATION AND HYDROPHOBIZATION OF CELLULOSE

2020 ◽  
pp. 1-10
Author(s):  
Norbert Banyi ◽  
Jordan Hassett
Keyword(s):  
Contact Angle ◽  
Surface Modification ◽  
Water Droplet ◽  
Contact Angles ◽  
Water Droplets ◽  
Treatment Groups ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Silylation Reaction

In order to improve the quality of paper straws, experiments involving the hydrophobization of paper, in a silylation reaction with chloro(dimethyl)octadecylsilane using various solvents, were conducted. The ImageJ program was used to quantify hydrophobicity by calculating the contact angle between a water droplet and a small piece of paper, which were compared between treatment groups as well as with untreated paper and plastic straws. Samples were exposed to a variety of liquids in one-hour periods for a total of six hours. After each hour, contact angle measurements were taken. Results suggested that hydrophobicity declines with time due to leaching of silanol from the treated paper. Contact angles between water droplets and the treated paper remained larger than that of untreated paper straws throughout testing, indicating higher hydrophobicity. Furthermore, samples that were silylated using dioxane as a solvent were better able to maintain hydrophobicity than samples silylated using toluene as a solvent.

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