Surface strength, coating

Rehbinder and co-workers were pioneers in the study of environmental effects on the strength of solids [144], As discussed by Frumkin and others [143-145], the measured hardness of a metal immersed in an electrolyte solution varies with applied potential in the manner of an electrocapillary curve (see Section V-7). A dramatic demonstration of this so-called Rehbinder effect is the easy deformation of single crystals of tin and of zinc if the surface is coated with an oleic acid monolayer [144]. 

Surface Sizing. Surface sizing is generally used for modification of other properties of paper or paperboard such as printabiHty, smoothness, porosity, coefficient of friction, opacity, surface strength, anti-linting or coating holdout. Anionic starch is perhaps the most common additive or co-additive used for surface sizing. 

To determine the wet bond strength coated panels were immersed in distilled water for 1500 h, removed and discs 25.4 mm in diameter stamped from them. The surfaces were wiped with a dry tissue and bonded between two cylindrical test pieces using a polyamide cured epoxide adhesive and immediately placed in a sealed container at 100% RH for the adhesive to cure. After 16 h the specimens were broken on an Instron Universal Test Machine with minimum delay. Recovered values were measured after the panels had dried out at room temperature and humidity for 7 days. Clearly, it is unlikely that the values reported represent the minimum bond strengths, as some drying out is almost inevitable, but the values are directly comparable. 

Phosphorylcholine (PC) coating is a polymer that mimics the human chemistry of the cell membrane surface. The PC polymer is biocompatible, because it has hydrophobic areas that stick to each other and to the metal, and it is also cross-linked for strength, Its high water affinity allows for water to be attracted to its surface, PC-coated devices have a permanent water layer on the surface, again serving as a potentially biocompatible surface. 

An alternative method to apply starch to paper, especially to paperboard grades, is to use a water box at the calender. Water boxes are used for wet-finishing of paper-board prior to coating application. Use of starch in the water box will increase surface strength and lessen fiber reswelling after coating application. Dilute dispersions of oxidized starch are used, frequently in conjunction with a lubricant to prevent calender roll picking. 

Picking n. (1) The adherence of a sheet of paper to the plate due to the tack of the ink. (2) The removal of the surface of the paper during printing. It occurs when the pulling force (tack) of the ink is greater than the surface strength of the paper whether coated or uncoated. 

Stone, I. K. and Masterson, B. J. (1986). Knot stability and tensile strength of an absorbable suture material. Surface and Coatings Technology, 27,287-293. 

Once cleaned, the metal surfaces are coated with a primer prepared by rollmilling 200 g of adhesive composition and 5(X) g of methanol. A first layer of primer is appUed to the metal parts, dried for 10 min at 90°C, covered with a second layer of primer and finally dried at 90°C for 1 h in an air circulating oven. The adhesive film is inserted between the two primed metal surfaces and the assembly is placed between the platens of a hydraulic press preheated to 316°C. A pressure of 0.3-0.5 MPa is applied and the test specimens are cured at 316°C for 1.5 h, before cooling down to 100°C under pressure. The assemblies are removed from the press and postcured in an air circulating oven as follows the temperature is raised from 20 to 300°C in 1 h, then from 300 to 350°C in 5 h and left at 350°C for 5 h. The lap shear strength values determined at different temperatures are plotted in Fig. 29 for TU-2 Ti/li assemblies [curve (a)] and ZIO CNT 1810 stainless steel coupons [curve (b)]. 

Modern materials (e.g. Nafion 901) make use of the best features of both materials, see Figure 7. Most of the membrane is fabricated from the sulphonate resin to obtain the low resistance but the catholyte surface is coated with a thin film of carboxylate resin which permits the high caustic soda concentration to be produced. The plastic net gives the membrane additional mechanical and physical strength. 

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