Epoxy resins, glues

Resins, especially those containing epoxy, colophony, and PTEP-FR, are used as adhesives and glues in sports equipment. Reports of contact allergy include facial dermatitis from epoxy resin glue inside a helmet (Malanin and Kalimo 1985), erythematous facial dermatitis from colophony in a bowlsgrip (Elair 1982), and a well-demarcated linear erythematous vesicular patch on the back of a leg from the PTEP-FR and/or phenol-formaldehyde resin in a knee-guard (Vincenzi et al. 1992). 

Epoxy resins have outstanding mechanical and electrical properties, dimensional stability, resistance to heat and chemicals, and adhesion to other materials. They are used for casting, potting, encapsulation, protective coatings, and adhesives. Epoxy glues separate the resin from the curing. igciU to be mixed just prior to use. 

Few non.chemists know exactly what an epoxide is. but practically everyone has used an "epoxy glue for household repairs or an epoxy resin for a protective coating. Epoxy resins and adhesives generally consist of two components that are mixed just prior to use. One component is a liquid "prepolymer/ and the second is a "curing agent" that reacts with the prepolymer and causes it to solidify. 

At the same time, natural adhesives such as casein glues, animal glue and polysaccharide gums have gradually been replaced by synthetic adhesives vinyl thermoplastic adhesives [poly(vinyl acetate)], adhesives obtained by reticulation in situ of two components (as epoxy resins), represent very important materials in this field. 

Phenol is also used to manufacture several important monomers. Bisphenol A, a phenol derivative, is used to make very strong polycarbonate plastics and epoxy resins (the kind you buy in two tubes and mix to make glue). Ocher applications of epoxy resins include paints, fiberglass binder, and construction adhesives. 

The gluability of the lignin-epoxy resin adhesives was found to be improved by the addition of calcium carbonate (50% by weight) to the liquid resin. This must be attributed to the nature of the weak alkali in calcium carbonate as a cure accelerator, and to the reinforcement effect of fillers. Since wood surfaces are acidic, the addition of alkaline fillers effectively alters the pH of the glue line. 

The simplest way to construct these electrodes is to solder or glue with silver epoxy resin a cylindrical specimen of the electrode material to a stainless steel shaft. A mantle of epoxy resin or plastic is then made around the disc to the shape required. 

Mechanism 14-4 Base-Catalyzed Opening of Epoxides 653 14-14 Orientation of Epoxide Ring Opening 654 14-15 Reactions of Epoxides with Grignard and Organolithium Reagents 656 14-16 Epoxy Resins The Advent of Modern Glues 656 Summary Reactions of Epoxides 658 EssentialTerms 660 Study Problems 662... 

Composites based on silver powder can be made with conductivities as high as 10 6fl 1m 1 at a loading of 85% by mass, when the insulating matrix, which may be an epoxy resin, serves essentially as a glue to hold the metal powder in position without altogether disrupting the metal-metal particle contacts. 

Epoxy resins represent a class of step-growth polymer familiar to anyone who has used epoxy to glue together a broken object. An epoxy resin consists of two components a fluid prepolymer composed of short polymer chains with reactive epoxides on each end, and a hardener, usually a diamine or triamine that ring opens the epoxides and cross-links the chains together. 

Both of the periods of linear temperature rise AT, and AT2 were used to calculate power (see Figure 8). The plots are normalized with respect to the maximum value using both periods and were shown to be very similar. Several different absorbing coatings were used glues (polystyrene cement and UHU), epoxy resins, silicone rubber, polyurethane varnish, and cellulose lacquer. The diameter and length of the beads were varied within the ranges 0.5-0.8 mm and 0.68-1 mm. 

Epoxy adhesives Glue, except dental animal, vegetable, fish, casein, and synthetic resin Iron cement, household Joint compounds Laminating compounds Mucilage... 

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