Polymer surface treatment

In the past, BCME was used for crosslinking of cellulose, preparation of styrene and other polymers, surface treatment of vulcanized rubber to increase adhesion, and in the manufacture of flameretardant fabrics (EPA 1980a). These applications have been discontinued, and no uses of BCME other than as a nonisolated intermediate were identified. 

Kubey W Lunebueg P, Ericson S, Brown J and Holmes CJ (1995) A longitudinal in vitro antimicrobial evaluation of two silver polymer surface treatments for peritoneal dialysis catheters. Adv Peril Dial 11 193-197. 

E) ESCA Studies of Structural Isomerism Structural Elucidation of Polymers Surface Treatment of Polymers... 

J. (John) F. Watts received a Ph.D. in materials science from the University of Surrey in England in 1981 and was awarded a D.Sc. in 1997 from the same university. He subsequently returned to an academic position in Adhesion Science at Surrey, where he now heads the Surface and Interface Reaction Group. Current research interests arc concerned with aspects of adhesion and polymer surface treatment, and with the applications of XPS, AES. ToF-SIMS. and SPM to those problems, He is the author of an introductory text and a software package on electron spectroscopy, and has lectured widely in Europe, the United States, and the Far East. 

Wertheimer, M.R., Martinu, L, and Liston, E.M. (1996) Plasma sources for polymer surface treatment, in Handbook of Thin Film Process Technology (eds D.A. Glocker and S.I. Shah), lOP Publishing, Bristol. 

An atom or a surface can be acidic or basic in nature. An acid is an electron acceptor and a base is an electron donor. The degree of acidity or basity is dependent on the materials in contact. An acidic surface will react with a basic atom while a basic surface will react with an acidic atom. The electronic nature of a surface can be changed by changing the chemical composition. Polymer surfaces can be acidic or basic in nature. Polymer surface treatments, such as oxygen or nitrogen plasma or chromic acid or other acid treatments, make the polymer surface more acidic and thus able to react with many metallic atoms. An amphoteric material is one that can act as either an acid or a base in a chemical reaction. Aluminum is an example of an amphoteric material and shows good adhesion to both acidic and basic polymer surfaces. 

Fluorine was first produced commercially ca 50 years after its discovery. In the intervening period, fluorine chemistry was restricted to the development of various types of electrolytic cells on a laboratory scale. In World War 11, the demand for uranium hexafluoride [7783-81-5] UF, in the United States and United Kingdom, and chlorine trifluoride [7790-91 -2J, CIF, in Germany, led to the development of commercial fluorine-generating cells. The main use of fluorine in the 1990s is in the production of UF for the nuclear power industry (see Nuclearreactors). However, its use in the preparation of some specialty products and in the surface treatment of polymers is growing. 

An important newer use of fluorine is in the preparation of a polymer surface for adhesives (qv) or coatings (qv). In this apphcation the surfaces of a variety of polymers, eg, EPDM mbber, polyethylene—vinyl acetate foams, and mbber tine scrap, that are difficult or impossible to prepare by other methods are easily and quickly treated. Fluorine surface preparation, unlike wet-chemical surface treatment, does not generate large amounts of hazardous wastes and has been demonstrated to be much more effective than plasma or corona surface treatments. Figure 5 details the commercially available equipment for surface treating plastic components. Equipment to continuously treat fabrics, films, sheet foams, and other web materials is also available. 

The surface of PTFE articles is sHppery and smooth. Liquids with surface tensions below 18 mN/m(=dyn/cm) are spread completely on the PTFE surface hence, solutions of various perfluorocarbon acids in water wet the polymer (78). Treatment with alkafl metals promotes the adhesion between PTFE and other substances (79) but increases the coefficient of friction (80). 

Permeant movement is a physical process that has both a thermodynamic and a kinetic component. For polymers without special surface treatments, the thermodynamic contribution is ia the solution step. The permeant partitions between the environment and the polymer according to thermodynamic rules of solution. The kinetic contribution is ia the diffusion. The net rate of movement is dependent on the speed of permeant movement and the availabiHty of new vacancies ia the polymer. 

Uses. /-Butyl hypochlorite has been found useful in upgrading vegetable oils (273) and in the preparation of a-substituted acryflc acid esters (274) and esters of isoprene halohydrins (275). Numerous patents describe its use in cross-linking of polymers (qv) (276), in surface treatment of mbber (qv) (277), and in odor control of polymer latexes (278). It is used in the preparation of propylene oxide (qv) in high yield with Httle or no by-products (269,279). Fluoroalkyl hypochlorites are useful as insecticides, initiators for polymerizations, and bleaching and chlorinating agents (280). 

Treatment of polymer surfaces to improve their wetting, water repulsion, and adhesive properties is now a standard procedure. The treatment is designed to change the chemistry of the outermost groups in the polymer chain without affecting bulk polymer properties. Any study of the effects of treatment therefore requires a technique that is specific mostly to the outer atomic layers this is why SSIMS is extensively used in this area. 

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. 

A very simple, though indirect, method of surface analysis is the measurement of the angle of contact that a liquid makes with the solid surface being analyzed. This method has been widely used to study changes introduced in a polymer surface by various treatments. 

The diffusion of electrons plays a major role in the surface treatment of polymers in a gas plasma apparatus. The adhesion of PE tapes increases to a maximum by this treatment at 0.20 to 0.30 A for 20 to 30 s [40]. IR absorption at 1600-1750 cm increases 1.5-fold on discharge treatment owing to the formation of polar >C==0 and —COOH groups, which increase tape adhesion. 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

Corona discharge treatment results in the formation of high-polarity functional groups, such as carbonyl, at the polymer surface. Various mechanisms have been proposed for the improvement of the adhesive properties... 

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