The surfaces and hidden interfaces of polymers play an important role in the properties and applications of polymers. The surface should be defined as the plane at which the membrane terminates, in other words, the last atom layer before the adjacent phase begins.A solid’s surface energy is a particularly important property in the understanding and prediction of many surface phenomena such as adhesion, friction and bonding. It accounts for the reactivity of materials and is associated with the asymmetric force field to which the surface atoms are subjected. As we have discussed previously, it is this asymmetry that leads to the appearance of dangling bonds that allow the solid’s surface to interact with its environment.
Surface energy is sensitive to temperature. With increased temperature the network atoms vibrate with increasing amplitude, leading to a decrease in the cohesion energy of the material and a decrease in surface energy. The adsorption of contaminants on a material’s surface, or its oxidation, can also lead to a significant drop in surface energy that can decrease by over an order of magnitude. Mica, for instance, has a surface energy of 5000 mJ m–2 in ultra vacuum, while measurements in air yield a value of 300 mJ m–2.
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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