Surface tension is a fundamental property by which the gas–liquid interfaces are characterized. The zone between a gaseous phase and a liquid phase looks like a surface of zero thickness. The surface acts like a membrane under tension.
It reflects in principle directly the strength of bonding within the bulk material. Due to very different binding forces, hard solids (covalent, ionic, metallic) typically reveal “high-energy” surfaces (surface tension ~500–5000 mJ/m2) in contrast to weak molecular solids and liquids (soft matter) with “low-energy” surfaces (surface tension < 100 mJ/m2).
Most polymers belong to the second class of materials where interactions between chains are dominated by van der Waals forces and hydrogen bonds.
Surface and interfacial tensions of polymers play a key role in wetting and coating processes, in biocompatibility or polymer blending, and in corrosion and adsorption processes. The behavior of colloidal dispersions, adhesion, and friction is influenced by surface and interface tension. Surface tension of polymers can be divided into two components, polar (????) and dispersion (????) to account the type of attraction forces at the interfaces. The chemical constitution of the surface determines the relative contribution of each component to surface tension. The polar component is comprised of various polar molecular interaction including hydrogen bonding, dipole energy and induction energy, while the dispersion component arises from London dispersion attractions. The attractive forces (van der waals and London dispersion) are additive, which results in the surface tension component being additive: ?? = ???? + ????
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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