Neoprene rubber sealant

The use of plasticisers, with other than PVC applications, is extensive. Many polar rubber sealants or caulking materials are plasticised in order to make them more pliable, e.g., polysulfides, polychloroprene (Neoprene ), nitrile rubber. Esters, similar to those employed with PVC, are used to render cellulose diacetate ("Acetate") overhead projection sheets more flexible. 

Synthetic rubber, a dimethylbutadiene, was developed as a substitute for natural rubber in Germany during World War I and saw limited use as an adhesive. In the early 1930s, neoprene rubber (then called Duprene) became available to adhesive manufacturers in the United States, and shortly thereafter in Great Britain. Today, neoprene rubber adhesives are available as both thermoplastic and cross-linking systems in both solvent and emulsion formulations. Neoprene rubber is the major base resin for contact adhesives. A limited amount of neoprene rubber is also used in sealants. 

Concrete pipe seals - Butyl sealant tapes and neoprene rubber are frequently used as concrete pipe seals. The neoprene seals have very good chemical resistance. 

In general, polysulfide sealants resist attack from fuels and water and have good chemical resistance. Polyurethane sealants are especially resistant to alkali exposure. Polyurethane, acrylic, and polychloroprene (neoprene) are all moisture resistant. Both polychloroprene and butyl rubber sealants have good general chemical resistance. Silicones, although expensive, are often the sealant of choice, because they are strongly resistant to moisture and all chemicals. Silicones are also the most resistant sealants to UV and solar radiation. 

The need to maintain elasticity of rubber is of paramount importance under any serious and severe environmental conditions. The most stable rubbers in radiation environments are polyurethanes and phenyl silaxanes which are usable at well above 108 rads (106 Gy). Butyl rubber liquefies and neoprene evolves hydrochloric acid at similar dose levels. Most polyurethane rubber foams can be used at a dose level of 109 rads (107Gy) in vacuum at temperature levels of between -85°C to +250°C. Silicone and polysulphide sealants are probably less tolerant to ionizing radiation in a nuclear plant where chemical processes are being carried out. A schematic graphical representation of the tolerance of rubbers to ionizing radiation in nuclear plant is shown below in figure 7.4. 

Neoprene. [DiiPont DuPont UK] Poly-chloroprene versatile synthetic rubber fw wire/cable industrial hose and belting automotive gaskets, seals, hose tire sidewalls molded and extruded goods cellular prods. adhesives, sealants, and protective coatings for shoe, home crafts, sporting goods. 

Liquid natural rubber, SBR, acrylonitrile elastomers, neoprene, and chlorosulfonated polyethylene are also used as sealant compositions. Filled depolymerized natural rubber and SBR latex are readily cured at room temperature by the incorporation of ultraaccelerators. 

Uses Tackifier resin for water-based adhesives and sealants based on acrylic, S/B, nat. rubber, neoprene, and PVAc, esp. for pressure-sensitive adhesives, and for coatings Features Solv.-free... 

Uses Coupling agent esp. for polyolefins and polyolefin elastomers, min.-and glass-filled formulations, sealants (acrylic, SBR), rubbers (butyl, neoprene, isoprene, fluorocarbon), as primer coal for metals in insert molding... 

Extruded Tapes. These are preformed ribbons or profiles of butyl rubber, neoprene, or polyvinyl chloride, and may be either solid or expanded. They may be supplied as composite structures with rubber cores, rubber rod spacer, or aluminum shims surrounded or embedded in an adhesive or sealant. 

Rubber tubing made of neoprene, EPDM, or butyl is an excellent but expensive backup material. In essence, the tubing acts as a duad system with the sealant, since the partly compressed tubing will also act as a water barrier in case the sealant suffers a loss of adhesion. 

Formed-in-place gaskets - Silicone RTV sealants are widely used in this application for valve covers, oil pans, thermostats, rear view mirrors. Neoprene sealants have excellent oil and chemical resistance and SBR sealants give good bonding to oily surfaces. Gunnable butyl rubber mastics are used for vibration dampening of panels and as general sealants for frame and body parts. 

Bentonite thickening agents are used in various water based adhesives, caulks and sealants including those based on proteins and starch, polyvinyl acetate emulsions, natural rubber latexes, acrylic emulsions, neoprene emulsions, butyl emulsions, nitrile emulsions, and SBR emulsions. 

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