Adherents surface treatment

Contact mechanics, in the classical sense, describes the behavior of solids in contact under the action of an external load. The first studies in the area of contact mechanics date back to the seminal publication "On the contact of elastic solids of Heinrich Hertz in 1882 [ 1 ]. The original Hertz theory was applied to frictionless non-adhering surfaces of perfectly elastic solids. Lee and Radok [2], Graham [3], and Yang [4] developed the theories of contact mechanics of viscoelastic solids. None of these treatments, however, accounted for the role of interfacial adhesive interactions. 

While polymeric surfaces with relatively high surface energies (e.g. polyimides, ABS, polycarbonate, polyamides) can be adhered to readily without surface treatment, low surface energy polymers such as olefins, silicones, and fluoropolymers require surface treatments to increase the surface energy. Various oxidation techniques (such as flame, corona, plasma treatment, or chromic acid etching) allow strong bonds to be obtained to such polymers. 

One of the problems encountered in early polyester fibre processing was that the sizes generally used with other classes of fibre to protect yarns, particularly warp yams, against damage during weaving were not sufficiently adherent to the yarn. ICI found a surface treatment that would improve the adhesion of sizes to... 

Sometimes primers can take the place of surface treatments. Two examples are with porous substrates and with certain plastic substrates. With weak porous substrates, such as wood, cement, or porous stone, the primer can be formulated to penetrate and bind weakly adhering material to provide a new, tightly anchored surface for the adhesive. Chlorinated polyolefin primers will increase the adhesion of coatings and adhesives to polypropylene and to thermoplastic olefins. The chlorine atoms in the outer surface of the primer increase surface energy and enhance adhesion of adhesives, sealants, and paints. 

The effect of the surface treatment for longer UV—ozone treatment times (60 min, water contact angle <30°) in terms of adherence and the laterally inhomogeneous distribution of pull-off forces provide evidence for the successful and complete oxidation of the previously hydrophobic PDMS surfaces. Upon storage in ambient conditions, one can observe that the forces gradually increase in heterogeneity with... 

Fouling (e.g., microbial adhesion, gel layer formation, and solute adhesion) at the membrane surface is a more complex phenomenon involving polarization, irreversible adsorption of macrosolutes or colloid particulates to, and/or gradual buildup of an adherent and coherent layer of solid material on, the membrane surface. It is amenable to mitigation by appropriate selection or surface treatment of the membrane surface (to minimize adsorption) by suitable fluid management or by employment of other forces to transport fouhng solutes. 

A fresh surface of thermally grown silicon dioxide, it must be pointed out, is hydrophobic. However, it quickly reacts with water vapor in the atmosphere to form silanol (Si—OH) and gradually becomes hydrophilic. In fact, the chemical vapor deposition of silicon dioxide forms only a silanolated surface. Being fairly hydrophobic, resists do not adhere well to hydrophilic surfaces such as Si02-These surfaces contain hydroxyl groups as illustrated in Reaction [11.1]. The adhesion failure of resist films on such surfaces is often observed in the course of development or wet etching. As a result, a surface treatment to promote adhesion is necessary before the resist film is deposited on such surfaces. ... 

Adhesion to plasticized PVC is often poorly effective because migrating plasticizer contaminates surfaces. In this case, pretreatment comprises cleaning with a ketone solvent such as acetone. Polystyrene, nylon, melamine-formaldehydes and polyesters can be pretreated by abrading with an emery cloth prior to cleaning with an alcohol. The effectiveness of all surface treatments decrease rapidly with time, so it is necessary to both modify and adhere within a short period. 

Polyolefins, such as PE and PP, are commonly used in many applications in the biomedical sector. PE and PP can achieve biocompatible and antimicrobial properties using the suitable surface treatment [131, 132]. Many modification methods of the polymer surfaces have been employed, for example, techniques based on the plasma treatment [133]. A deposition of chitosan on the plasma-pretreated PP surface provides antifungal and antibacterial properties because chitosan exhibits an efficient antimicrobial activity [134]. If PE films were modified by a multistep process using plasma discharge, carboxylic groups and antibacterial agent can be developed over the surface. Immersion of these films into the solution of chitosan leads most likely to the adherence of a chitosan monolayer on the treated film. Small concentration of chitosan was enough for the induction of antimicrobial properties to the modified material [135]. 

The principal aim of the present work was to study the modification of polymer surfaces by plasma treatment as well as the interaction of a metal film with these treated surfaces by surface analytical techniques. As shown above, the results indeed show increased interaction after surface treatment under certain conditions. However, ultimately, improved adhesion should also be observed. For this purpose preliminary expenments with aluminum films on plasma treated polypropylene were carried out. These films were not evaporated under in-situ conditions, but in a separate electron beam evaporator under identical conditions for the different polymer surfaces. A simple Scotch tape test was performed in order to characterize the adhesion qualitatively. In agreement with the surface analytical results, the as-received polypropylene surfaces show poor adhesion as the aluminum film and can be peeled off completely. A five second nitrogen plasma treatment however leads to a film which adheres well and cannot be lifted off by the same tape. Hnally, a 120 s ocatment in a nitrogen plaana leads to an oveitreatmcntof the surface characterized by a low adherion again. 

EPI adhesives have very good adhesion properties to the wood surface and thus can glue different wood species very well. Since this adhesive type also has very good adhesion to materials like metals, plastics and foams, it is very well suited for gluing composite materials where wood is combined with other materials [2,4, 5]. The excellent adhesion of EPI adhesives to metals has to be taken into account in the production process since the glued pieces may adhere to the press plates if no surface treatment of the press plates is used. Release agents are available and are in use. 

Before applying the first layer of resin, the surface can be treated with a primer that has the task of promoting adherence. This first layer also creates a barrier against the penetration of humidity and ensures the durability of the reinforcement system in the case of galvanized steel or stainless steel the oxides formed on the surface must be removed wifli an appropriate surface treatment. 

---