Surface energy mechanical abrasion

Since slower-curing epoxy adhesives systems flow over and wet high-energy surfaces very well, there is little chance for air to become trapped at the interface. As a result, mechanical abrasion is often recommended as a substrate surface treatment prior to application of the epoxy adhesive. The added surface area and the mechanical bonding provided by the additional peaks and valleys on the surface will enhance adhesive strength. If the adhesive does not wet the substrate surface well, such as in the case of epoxy resin on polyethylene, mechanical abrasion is not recommended since it will only encourage the probability of gas voids being trapped at the interface. 

In comparison with metals, most conventional polymers are low in wear resistance. For wear control, we need to understand various wear mechanisms for each polymer system (V). As discussed in a previous paper, for adhesive wear, surface energetics can determine the extent of surface wear. Thus, a low surface energy is preferred to minimize the surface attrition. In addition, a harder polymer is desired to lower the wear rate. For abrasive wear, fracture energetics become important a harder and tougher material should be more wear resistant. 

By contrast, active fillers, exclusively selected fi om different kinds of pyrogenic silica with BET surfaces of 90-350 mVg, are able to strongly interact with both themselves and the dimethylsiloxane polymers, which is due to their high surface energy and ability to form hydrogen bridges. This interaction results in a marked increase in mechanical strength, mainly abrasion and tear resistance, of the cured rubber. 

The term ATm can be modeled following the Preston formalism (Rock et al., 2011) = PvKp, where P and v are the down pressure and the platen speed of CMP, respectively. ATp is an effective Preston coefficient. Kp = (mEm)/Bmc. with Bmc and Tm denoting the molar binding energy and molar volume of MC, respectively fi is the effective coefficient of friction of the pad—metal interface. In this description of chemically dominated CMP, one has MRR = 0 if the surface complex does not form. If no surface complexes or soluble species are formed, and if mechanical abrasion of the unmodified metal surface is the only means of material removal, then Eqn... 

Figure 9.17 Field emission scanning electron microscope images of the bulk material at low (a) and high (b) magnification (c) water droplets exhibit spherical shape on the surface of the bulk material (d) mirror-like phenomenon can be observed on the bulk material submerged in water and (e) optical image and contact angle profile of the water droplet placed on the abraded bulk material. Bottom schematic illustration of a bulk material which can still sustain its superhydrophobicity after mechanical abrasion because of the low surface energy microstructures extending throughout its volume. Reproduced from [87,88] with permission of The Royal Society of Chemistry.

Mechanical processing (e.g., abrasion) of metallic surfaces causes the emission of electrons this is known as the Kramer effect (Kramer 1950). The effect has been shown by the measurement of selfgenerated voltages between two metallic surfaces under boundary lubrication (Anderson et al. 1969, Adams and Foley 1975). The exoelectrons have a kinetic energy from 1 to 4 eV (Kobzev 1962) and they may initiate some chemical reactions. For instance, if the metal (whose surface has been worked) is placed in an aqueous solution of acrylonitrile, the latter forms an abundant amount of an insoluble... 

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