Adherent substrates

Another way to determine durabHity is to find successfuHy sealed, existing field instaHations. Sealant manufacturers often have case histories of successful instaHations. Adhesion performance can vary widely with sealant type, substrate type, and cleaning method. Eor this reason, it is important to understand the sealant s sensitivity to cleaning practices. Often with difficult-to-adhere substrates, a primer is used. Sealant manufacturers can provide recommendations as to which substrates require primers, what type of primers should be used, and how they should be appHed. 

For particularly difficult to adhere substrates such as metallized or fluorocarbon treated surfaces the same principles that are applied in freezer grade adhesives are used. For especially difficult situations, styrenic block copolymers are added to... 

In present-day high-speed assembly line operations, adhesives are applied robotically. The adhesive bead is apphed quickly and evenly to parts on a conveyor line just prior to being fitted. These operations, especially the need to handle the adhered substrates soon after assembly, demand fast-curing adhesive systems [65]. Two-component adhesives are used to bond metals to plastics in automobiles, to laminate panels in the construction industry, to laminate foams to textiles, to laminate plastic films together, and to bond poly(vinyhdene chloride) films to wood for furniture. A commercial waterborne two-component adhesive is sold by Ashland under the trademark ISOSET. This system is used for exterior sandwich panels by recreational vehicle manufacturers and is composed of a water-emulsiliable isocyanate and a hydroxy-functionalized emulsion latex. 

Eierman, D. F., Johnson, C. E., and Haskill, J. S. (1989) Human monocyte inflammatory mediator gene expression is selectively regulated by adherence substrates. J. Immunol. 142,1970. 

Provides an adherable substrate for application of paint much superior to unmodified polyolefins. 

Cohesive failure is observed when a crack propagates in the bulk of the polymeric material which leads to failure (Figure 16a). In most cases, the surfaces of the adherents (substrate... 

MAJOR POLYMER APPLICATIONS for difficult-to-wet adhere substrates, such as polyester, polyolefins, PP, cellophane... 

An adhesive is a polymer mixture or polymerizable material in a liquid or semiliquid state that adheres substrates together (Petrie 2000). Adhesives maybe composed of many components such as polymer, oligomer, filler, and additives from either natural or synthetic sources. It is very important to understand the components for adhesive formulation. The information of composition gives us an adhesive selection guide based on functional properties, curing mechanisms, and other relevant information supplied by the adhesive manufacturer. 

The interest in vesicles as models for cell biomembranes has led to much work on the interactions within and between lipid layers. The primary contributions to vesicle stability and curvature include those familiar to us already, the electrostatic interactions between charged head groups (Chapter V) and the van der Waals interaction between layers (Chapter VI). An additional force due to thermal fluctuations in membranes produces a steric repulsion between membranes known as the Helfrich or undulation interaction. This force has been quantified by Sackmann and co-workers using reflection interference contrast microscopy to monitor vesicles weakly adhering to a solid substrate [78]. Membrane fluctuation forces may influence the interactions between proteins embedded in them [79]. Finally, in balance with these forces, bending elasticity helps determine shape transitions [80], interactions between inclusions [81], aggregation of membrane junctions [82], and unbinding of pinched membranes [83]. Specific interactions between membrane embedded receptors add an additional complication to biomembrane behavior. These have been stud-... 

The utihty of these adhesives arises from the electron-withdrawing character of the groups adjacent to the polymerizable double bond, which accounts for both the extremely high reactivity or cure rate and thek polar nature, which enables the polymers to adhere tenaciously to many diverse substrates. 

Although CD-modified BPA polycarbonate can be employed without problems for CD-DA and CD-ROM, the use as a substrate material for EOD(MOR) requites an optimum selection and meticulous adherence to production conditions to achieve the requited birefringence values of less than 20 nm/mm (184,193). 

The inks formulated for jet printing must be very fluid, stable, and free of any particles that could cause clogging of the jet nozzles, and be capable of depositing and adhering to a substrate with a minimum of character fogging. They are generally formulated with soluble dye colorants in a suitable aqueous or solvent-based vehicle (9). 

Niobium is used as a substrate for platinum in impressed-current cathodic protection anodes because of its high anodic breakdown potential (100 V in seawater), good mechanical properties, good electrical conductivity, and the formation of an adherent passive oxide film when it is anodized. Other uses for niobium metal are in vacuum tubes, high pressure sodium vapor lamps, and in the manufacture of catalysts. 

The coating has to adhere to the substrate. In older thermal spray technology, the bonding may be mechanical as a result of the interlocking between... 

Ba.lla.sted. A ballasted roof assembly consists of a membrane or membrane and substrate material (insulation, sHp sheet, etc) loosely laid over a deck with the assembly held in place using ballast. A minimum ballast weight of 48.9 kg/m or 10 pounds per square foot (PSF) is used. The ballast can consist of smooth rounded stone, cmshed stone (a separator sheet must be used between the cmshed stone and the membrane), or pavers (both standard and lightweight). Both stone and pavers come in a wide variety of colors. The membrane is affixed to the building only at the deck perimeter (roof edge) and at various penetrations. Wall and penetration flashings are typically fuUy adhered and sealed to prevent water entry into the roof assembly. The maximum slope a ballasted system should be installed over is 16.7 cm/m. 

Fully Adhered. The substrate, ie, insulation, cover board, etc, that the single-ply membrane is to be attached to is either fuUy adhered or mechanically fastened to the deck. However, there are also appHcations where the membrane is adhered directly to the deck. The membrane is then adhered to the substrate. The typical method for adhering the membrane to the substrate is by applying a contact adhesive to the membrane and substrate, rolling the membrane into place, and brooming once the adhesive is ready. There are one-sided appHcations where the membrane is roUed directly into the adhesive that has been appHed to the substrate only. The membrane used in this appHcation method may be fleece-backed. FuUy adhered systems can be installed on any slope. The fuUy adhered appHcation offers a smooth surface that is easy to maintain and inspect, as weU as exceUent wind resistance on account of positive attachment. 

Fleece-Back Sheet. A fleece-back sheet is a nonreinforced polymeric membrane that has had a nonwoven mat made of polyester, weighing 101.7—203.4 g/m, laminated to the back of the sheet. The prime use of the fleece-back sheet is in the fully adhered roofing systems. The fleece provides the chemical separator, which eliminates the need for an adhesive that is compatible with the specific membrane or a compatible substrate. 

Adhesion Life. A second key factor in determining the durabHity of a sealant is the abHity of the sealant to adhere to the substrate through its lifetime. A sealant may have exceHent resistance to uv effects, but if it has poor adhesion performance and faHs adhesively, it is of Httie use. The same can be said of a sealant with superior adhesion characteristics but poor resistance to uv. Either situation results in a short performance life. 

Another approach is to coat the cutting tool material with a carbide former, such as titanium or siUcon or their respective carbides by CVD and deposit diamond on top of it. The carbide layer may serve as an iaterface between diamond and the cemented carbide, thus promoting good bonding. Yet another method to obtain adherent diamond coatings is laser-iaduced microwave CVD. By ablating the surface of the substrate with a laser (typically, ArF excimer laser) and coating this surface with diamond by microwave CVD, it is possible to improve the adhesion between the tool and the substrate. Partial success has been achieved ia this direction by many of these techniques. 

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