Mechanical anchors

As already indicated above, what one may consider a surface depends on the property under consideration. Adhesion is very much an outer atomic layer issue, unless one is dealing with materials like fibreboard in which the polymer resin may also be involved in mechanical anchoring onto the wood particles. Gloss and other optical properties are related to the penetration depth of optical radiation. The latter depends on the optical properties of the material, but in general involves more than a few micrometer thickness and therewith much more than the outer atomic layers only. It is thus the penetration depth of the probing technique that needs to be suitably selected with respect to the surface problem under investigation. Examples selected for various depths (< 10 nm, 10 s of nm, 100 nm, micrometer scale) have been presented in Chapter 10 of the book by Garton on Infrared Spectroscopy of Polymer Blends, Composites and Surfaces... 

Metal Mechanical anchor During or after moulding, self-tapping inserts... 

The mixture was stirred with a mechanical anchor stirrer at 50 rpm at 60 °C until completely dissolved. A stoichiometric amount of adipic acid (69.92 g, 0.48 mol) was... 

Mechanical anchoring of the glue in the surface. The surface should be rough or porous and the glue should be able to penetrate into all surface details. 

Surface modification (texturing) of polyimide through a metal clustering and migration process is reported. This process involves heat treatment of polyimide coated with a thin copper layer. Subsequent metallization of the textured surface leads to improved adhesion due to mechanical anchoring. Adhesion values of 7-10 lbs/in (ambient) and 4-6 lbs/in (after solder float) have been obtained. 

Although the correlation is quite convincing, acid/base interactions are not claimed to be the only explanation for the increased adhesion since many other mechanisms and phenomena, such as formation of an interphase, co-crosslinking, interdiffiision, mechanical anchoring and interfacial shrinkage could intervene. 

The proton-relay mechanism anchors the substrate by 3-point docking. 

When bonding compounded rubber to fabric, for the manufacture of fabric reinforced expansion joints in the chemical plant piping systems, mechanical anchoring between cotton/Nylon/fibre and compounded rubber should be sufficient to ensure good adhesion. Synthetic fibres require treatment with chemical coatings to secure maximum adhesion and bond [8, 9]. 

This type of interfacial layer forms on rough porous substrates. The film material fills the pores and other morphologically advantageous places when there is sufficient surface mobility and wetting, and a mechanical anchor is formed. The adhesion depends on the physical characteristics (particularly the shear strength and the plasticity) of the combination of materials. 

Palladium acts as a nucleating agent for the electroless deposition of copper. By treating the surface with palladium [II] chloride in hydrochloric add a monolayer or so of palladium is deposited on the TiW surface. The palladium chloride solution also contains 1% of hydrofluoric acid which attacks the silica, undercutting the TiW islands (Fig. 5(b)). Electroless copper is now deposited, nucleating on the palladium-covered TiW and growing from it. Finally copper is eleetrodeposited and is thus mechanically anchored to the silicon surface (Figs. 5(c) and (d)). 

Treatment of sisal fiber with alkali for making composites to increase interfacial adhesion is very conunon, but extent of effect is determined on the basis of quantity and duratitMi of treatment Alkali treatment makes the sisal fiber surface rougher by removing the waxy materials. The rough surface produced on the sisal fiber leads to better mechanical anchoring with the matrix [34]. 

Such mechanical anchoring appears to be a prime factor in bonding many porous substrates. Adhesives also frequently, bnt not always, bond better to abraded surfaces than to natural surfaces. This beneficial effect of snrface abrasion may be due to... 

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