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Grain Waste Product as Potential Bio-fiber Resources
Published in Abdullah Al-Mamun, Jonathan Y. Chen, Industrial Applications of Biopolymers and their Environmental Impact, 2020
The manifestation of surface energy is a state of tension at the surface of a liquid, as a consequence of which work is required to increase the surface area of a liquid. One definition of surface energy is the work required to increase the surface area of a substance by unit area. However, when both phases are condensed, (e.g., solid-solid, solid-liquid, and immiscible liquid-liquid interfaces) the free energy per unit area of the interface is called the interfacial energy. The surface free energy of the solid-liquid interface is defined by contact angle between the solid-liquid interfaces. Liquids that form contact angles greater than 90° are called nonwetting, and liquids that form a contact angle less than 90° are termed wetting. When the contact angle is 0°, the liquid wets the solid and spreads over the surface spontaneously. Hence, the smaller the contact angle the better its wettability. Most polymers have low values of surface free energy (20 to 45 mJ/m2), which decreases slightly with increased temperature [207, 208].
Lubrication of Human Joints
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
The frictional resistance in rolling and sliding is extremely small under fluid film conditions, and the coefficientsof friction are of the order of 0.01. However, if a film of fluid cannot be generated to separate the two surfaces, intímate contact can be prevented by a boundary lubricant. A good boundary lubricant attaches itself strongly to the solid surfaces by molecular forces and modifies the surface energy states of the opposing surfaces to prevent adhesion between them. This consequently reduces friction and minimizes the damage this adhesion can cause. Levels of coefficient of friction tend to be higher for boundary-lubricated surfaces, having values in the range of 0.1–0.5, and these values are independent of speed of sliding or load.
Dry Construction Mixtures and Mortars Based on Them Using the Dust of Clinker-Burning Furnaces
Published in Leonid Dvorkin, Vadim Zhitkovsky, Mohammed Sonebi, Vitaliy Marchuk, Yurii Stepasiuk, Improving Concrete and Mortar Using Modified Ash and Slag Cements, 2020
Leonid Dvorkin, Vadim Zhitkovsky, Mohammed Sonebi, Vitaliy Marchuk, Yurii Stepasiuk
The main role in the formation of adhesive strength is assigned to the ratio of the surface energy of the adhesive and the substrate. The value of surface energy is component of the total energy of substances, determined by the characteristics of their structure, chemical composition, dispersion, etc.
Development of durable superhydrophobic and UV protective cotton fabric via TiO2/trimethoxy(octadecyl)silane nanocomposite coating
Published in The Journal of The Textile Institute, 2021
Muhammad Zaman Khan, Jiri Militky, Vijay Baheti, Jakub Wiener, Michal Vik
Superhydrophobic fabrics with high water contact angles and low roll off angles have attained great interest due to their unique anti-wetting behavior and self-cleaning property. Due to many potential applications of such surfaces, many researchers have developed various techniques. These anti-wetting structures can be achieved by the two physical characteristics, micro-nano surface roughness and hydrophobicity due to low surface energy materials on top of rough structures. The superhydrophobic surfaces exhibits the water contact angles greater than 150° and roll-off angle less than 10°. To develop superhydrophobic structures modification of surface chemistry is necessary in combination with micro-nano surface roughness. Surface modification is carried out by using low surface energy materials such as fluorocarbon, organic silanes, fluorinated silanes, alkyl amines and silicates (Afzal et al., 2014; Ashraf et al., 2014; Grozea et al., 2015; Xu & Cai, 2008).
Properties and electronic structure of Al/Mo2C interfaces: insights from first principle simulation
Published in Philosophical Magazine, 2021
Zhangxi Wu, Yongzhong Zhan, Lu Xiong, Zihao Li
The convergence criterion of surface layer is usually based on the variation trend of interlayer spacing or the variation trend of surface energy. The change of interlayer spacing (Δij) is the percentage of the difference between the spacing between i and j before relaxation and the spacing between the adjacent i and j layers after relaxation to the spacing between i and j in ideal crystal. Surface energy is usually defined as the reversible work per unit area required to establish a particular surface. When the interlayer spacing (Δij) is used as the criterion, the surface structure can be considered to begin to converge only when the change value of the layer spacing is close to repetition and there are negative values on both sides of the positive change value. When the surface energy is used as a reference, it is required that the front and back change of the surface energy result is about 0.02 J m−2.
Investigation on the effect of process parameters in atmospheric pressure plasma treatment on carbon fiber reinforced polymer surfaces for bonding
Published in Materials and Manufacturing Processes, 2019
Mahdi Yoozbashizadeh, Marios Chartosias, Chad Victorino, Doug Decker
An effective surface preparation technique has to meet at least one of the following conditions: it should increase the surface energy, increase surface roughness, or be able to change the chemistry of the surface of the CFRP. An increase in surface energy, or surface activation, allows for a more intimate contact between the surface and the adhesive due to better wetting of the adhesive on the surface. This assists in the development of secondary bonds. The increase in surface roughness provides a larger surface area for the adhesive to work and allows for mechanical interlocks to be created due to the irregular surface profile. Modifying the chemistry of the surface can promote better bonding between the surface and the adhesive.[3–5]