Techniques for determining contact angle and wettability of powders

Alghunaim, Abdullah; Kirdponpattara, Suchata; Newby, Bi‐min Zhang

doi:10.1016/j.powtec.2015.10.002

Cited by 269 publications

(179 citation statements)

References 104 publications

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“…Jet‐milling increased the surface hydrophobicity of MPC85 through exposure of buried hydrophobic residues as was also reported for acid casein (Hayakawa and others ). Water droplet profile change by spread over and absorption into pressed surfaces has been used to describe powder wettability (Alghunaim and others ). Contact angle on the control decreased rapidly within the first few seconds, but then it decreased at a rate similar to the droplets on the modified MPC85s (Figure A).…”

Section: Resultsmentioning

confidence: 99%

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High‐Protein Nutrition Bars During Storage

Banach

Clark

Lamsal

2017

Journal of Food Science

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Milk protein concentrate powder with 85% protein (MPC85) was jet-milled to give 2 particle size distributions (that is, JM-Coarse and JM-Fine) or freeze-dried (FD), in order to improve the functional properties of MPC85 for use in high-protein nutrition (HPN) bars. Volume-weighted mean diameter decreased from 86 μm to 49, 22, and 8 μm in FD, JM-Coarse, and JM-Fine, respectively (P < 0.05). The MPC85 powders modified by jet-milling and freeze-drying were significantly denser than the control MPC85 (P < 0.05). Volume of occluded air in the modified powders decreased (P < 0.05) by an order of magnitude, yet only FD possessed a lower volume of interstitial air (P < 0.05). Particle size reduction and freeze-drying MPC85 decreased its water holding capacity and improved its dispersibility by at least 20%. Contact angle measurements showed that these modifications increased initial hydrophobicity and did not improve wettability. HPN bars made from JM-Fine or FD were firmer by 40 or 17 N, respectively, than the control on day 0 (P < 0.05). HPN bar maximum compressive force increased by 38%, 33%, and 242% after 42 d at 32 °C when formulated with JM-Fine, FD, or control MPC85, respectively. HPN bars prepared with JM-Fine were less crumbly than those formulated with control or FD MPC85. Physically altering the particle structure of MPC85 improved its ability to plasticize within HPN bars and this improved their cohesiveness and textural stability. Volume-weighted mean diameter decreased from 86 micron to 49, 22, and 8 micron in FD, JMCoarse, and JM-Fine, respectively (P < 0.05). The MPC85 powders modified by jet-milling and freeze-drying were significantly denser than the control MPC85 (P < 0.05). Volume of occluded air in the modified powders decreased (P < 0.05) by an order of magnitude, yet only FD possessed a lower volume of interstitial air (P < 0.05). Physical modifications like particle size reduction or freeze-drying of MPC85 decreased water holding capacity and improved dispersibility by at least 20%. Contact angle measurements showed that these modifications increased initial hydrophobicity, yet did not improve wettability. HPN bars made from FD or JM-Fine were firmer by 40 or 17 N, respectively, than the control on day 0 (P < 0.05). HPN bar maximum compressive force increased by 38, 33, and 242% after 42 days at 32°C when formulated with FD, JM-Fine, or control MPC85, respectively. HPN bars prepared with JMFine were less crumbly than those formulated with control or FD MPC85. Physically altering the particle structure of MPC85 improved its ability to plasticize within HPN bars and this improved their cohesiveness and textural stability.Keywords: Jet-milling, freeze-drying, protein bar, texture profile analysis (TPA), cohesiveness 3 Practical ApplicationMilk protein concentrate (MPC) powder particle size significantly influences the texture of high-protein nutrition (HPN) bars. Use of finely jet-milled MPC85 powder produced HPN bars with increased firmness and cohesiveness. Particle size reduction improve...

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Section: Resultsmentioning

confidence: 99%

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High‐Protein Nutrition Bars During Storage

Banach

Clark

Lamsal

2017

Journal of Food Science

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“…Three methods to measure contact angles stand out for their applicability and reliability: the sessile drop (and its tilted plate variant), the Wilhelmy balance, and the Washburn capillary rise (WCR) methods (Table ). The sessile drop method requires a flat substrate of a few mm

^{2}

, while a plate‐ or disk‐like substrate—a few cm

^{2}

large—is needed for the Wilhelmy balance method.…”

Section: Introductionmentioning

confidence: 99%

Experimental methods in chemical engineering: Contact angles

et al. 2019

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The contact angle (CA) formed at equilibrium at the three‐phase line of contact between a liquid, a solid, and a gas may be expressed as a function of both the interfacial and surface tensions. Young first derived this thermodynamic relationship in 1805. In practice, multiple CA values are observed due to kinetic phenomena induced by evaporation, vapour adsorption, or swelling, and thermodynamic ones induced by roughness and surface chemical heterogeneities, even at molecular‐scale. These non‐ideal conditions result into an hysteresis, i.e., a difference between wetting and dewetting behaviours, and Young's equation rarely applies. Three measuring methods stand out for their applicability and reliability. In the sessile drop method, a syringe deposits a liquid drop on a flat surface and the contact angle is measured through optical means based on the drop shape. In the Wilhelmy balance method, the force required to immerse a solid plate in a bath of liquid is indirectly related to the contact angle. In the Washburn capillary rise method, the contact angle is derived from the rate at which a liquid rises by capillarity through a packed bed of powder. Employing probe liquids of various polarities, the free surface energy of the solid may be estimated. Over the last two years, ∼8600 published articles mentioned “contact angle” in their topic. Their main focus was either to develop the fundamental understanding of wetting science, or to assess the success of surface modification methods for the production of novel surfaces, composites, and membranes with enhanced wetting, adhesive, and filtration properties.

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“…The slope of the fitted line for the measured mass of the penetrating liquid as a function of time is used to determine the C value in Equation . Several kinds of factors, such as the pore structure, hydrophilicity of the separator, contact angle, and the surface tension, are associated with the wettability . For a more in‐depth investigation of the surface hydrophilicity, an XPS analysis was conducted.…”

Section: Resultsmentioning

confidence: 99%

“…Several kinds of factors, such as the pore structure, hydrophilicity of the separator, contact angle, and the surface tension, are associated with the wettability. 43,44 For a more in-depth investigation of the surface hydrophilicity, an XPS analysis was conducted. Figure 8 shows the chemical composition of the Zr, S, and C atoms as a function of Ar etching time using the XPS analysis.…”

Section: Ionic Resistance Of the Separatorsmentioning

confidence: 99%

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

et al. 2019

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Summary The rapid expansion of renewable energy sources presents a great challenge to balance the electric grid due to their intermittent and volatile nature. The surplus energy generation cannot be used or sold so that it is curtailed in order to maintain the grid balance. The excess power can be converted into a gaseous energy carrier, hydrogen via power‐to‐gas technology. Alkaline water electrolysis can be operated in a dynamic mode using renewable energy sources on a large scale. However, the risk of gas crossover across a porous separator rapidly increases when the electrolyzer operates at a low partial load or at high pressure, leading to efficiency loss and a safety issue. The commercial porous separator Zirfon PERL, which is composed of 85 wt.% zirconia nanoparticles and 15 wt.% polysulfone, exhibits a satisfactory bubble point pressure performance of approximately 2.5 bar and ionic resistance of 0.3 Ω cm2. However, the Zirfon PERL separator exhibits a high hydrogen permeability value of 20 × 10−12 mol cm−1 bar−1 sec−1 due to its large average pore size of 130 nm, resulting in a limited dynamic range of the electrolyzer. Therefore, it is necessary to develop a porous separator with reduced gas crossover. In this study, we synthesize a porous ZrO2/polysulfone composite separator by varying the amount of ZrO2 (75‐85 wt.%) via the film‐casting method. The 75 wt.% ZrO2/25 wt.% polysulfone composite separator, which contains a low amount of ZrO2, shows a high bubble point pressure of 3.8 bar, a low ionic resistance of 0.3 Ω cm2, and are reduced hydrogen permeability of 4.2 × 10−12 mol cm−1 bar−1 sec−1 compared with that of Zirfon PERL separator. The enhanced performance of this separator is attributed to the reduced average pore size of around 70 nm and high surface wettability with a contact angle of 75°. This result will help alkaline electrolyzer systems be operated as more controllable loads.

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Techniques for determining contact angle and wettability of powders

Cited by 269 publications

References 104 publications

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High‐Protein Nutrition Bars During Storage

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High‐Protein Nutrition Bars During Storage

Experimental methods in chemical engineering: Contact angles

The synthesis of a Zirfon‐type porous separator with reduced gas crossover for alkaline electrolyzer

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