Butyl rubber sealant

Edge Seals - The edge seals employed in this study were DC-790 and DC-738 from Dow Corning, GE 1200 from General Electric all three are silicones. One butyl rubber sealant, Adcoseal B-lOO was supplied by Adhesive Development and Chemical Operations, Inc. 

Polybutenes have heen used for almost a century and while they are still used, most of this type sealant contains butyl rubber, which is a copolymer of butene and isoprene. Most building specifications, including Federal Specification, TT-S-001637, require solutions of butyl rubber instead of oil-based caulking compositions. Self curing butyl rubber sealants may contain phenolic resins,IS. resorcinol and hexamethylenetetramine. ... 

Unvulcanized butyl rubber sealants Solid rubber sealants Sponge rubber sealants Sealants... 

Sealing compound, butyl rubber sealant (for use with ammunition)... 

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. 

Butyl mbber, a copolymer of isobutjiene with 0.5—2.5% isoprene to make vulcanization possible, is the most important commercial polymer made by cationic polymerization (see Elastomers, synthetic-butyl rubber). The polymerization is initiated by water in conjunction with AlCl and carried out at low temperature (—90 to —100° C) to prevent chain transfer that limits the molecular weight (1). Another important commercial appHcation of cationic polymerization is the manufacture of polybutenes, low molecular weight copolymers of isobutylene and a smaller amount of other butenes (1) used in adhesives, sealants, lubricants, viscosity improvers, etc. 

All grades of regular butyl rubber are tacky, rubbery and contain less unsaturation than natural rubber or styrene-butadiene rubber. On the other hand, low molecular weight grades of polyisobutylene are permanently tacky and are clear white semi-liquids, so they can be used as permanent tackifiers for cements, PSAs, hot-melt adhesives and sealants. Low molecular weight polyisobutylenes also provide softness and flexibility, and act as an adhesion promoter for difficult to adhere surfaces (e.g. polyolefins). 

Butyl ruhher vulcanizates have tensile strengths up to 2,000 psi, and are characterized hy low permeahility to air and a high resistance to many chemicals and to oxidation. These properties make it a suitable rubber for the production of tire inner tubes and inner liners of tubeless tires. The major use of butyl rubber is for inner tubes. Other uses include wire and cable insulation, steam hoses, mechanical goods, and adhesives. Chlorinated butyl is a low molecular weight polymer used as an adhesive and a sealant. 

Rubber-like materials now superseding the traditional mastics and putties used in the building industry. Such sealants (also termed mastics) are based on butyl rubber, liquid polysulphides, silicone rubbers, polybutylene, nitrile rubbers and plasticised vinyl polymers. SEBS... 

Butyl rubber (HR) is widely used for inner tubes and as a sealant. It is produced using the cationic polymerization with the copolymerization of isobutylene in the presence of a small amount (10%) of isoprene. Thus, the random copolymer chain contains a low concentration of widely spaced isolated double bonds, from the isoprene, that are later cross-linked when the butyl rubber is cured. A representation is shown in structure 5.20 where the number of units derived from isobutylene units greatly outnumbers the number of units derived from the isoprene monomer. The steric requirements of the isobutylene-derived units cause the chains to remain apart giving it a low stress to strain value and a low Tg. 

Exemplary materials for the waterproofing of masonry surfaces are waterproof membranes such as poly(vinyl chloride), PE, butyl rubber, and sealants such as tar, asphalt, paints, poly(urethane), epoxy or mastics. While these waterproofing agents can offer excellent resistance to water penetration and other contaminants, they can alter the appearance of the masonry surface, e.g., they may change the color of the surface or leave it with a shine. Waterproofing treatments can also trap moisture within the masonry surface and promote spalling. 

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. 

Sealants are often based on butyl rubber, polyisopropylene, polyurethane, or silicone rubber. Reactive sealants may be vulcanized at room temperature (RTV) or at high temperature (HTV). Silicone sealants are chemically-hardening, single-component systems in which cross-linking of the substrate is initiated by moisture from the air. This separates the reaction products. After rapid formation of a skin on the surface, cross-linking continues inside the mixture until it is fully hardened. 

Several organic sealants such as epoxy resins, butyl rubber or silicones prove to be more or less permeable and the tiny amount of solvent in the cell is rapidly lost. Suitable organic sealing materials for this technology turn out to be thermoplastic materials, like polyethylene/carboxylate copolymers. So far, Surlyn 1702 ionomer from Dupont has been the main substance used to optimize cell performance and build module prototypes. However, the softening point of Surlyn is rather low (65° C) and at elevated temperatures (> 70°C), serious solvent loss is observed because the bond between Surlyn and TCO-coated glass is substantially weakened [7]. 

The most important characteristics of butyl rubber are its low permeability to air and its thermal stability. These properties account for its major uses in inner tubes, tire inner liners, and tire curing bladders. Because of the poor compatibility of butyl with other rubbers (with respect to both solubility and cure), the halobutyls are preferred. The brominated p-methylstyrene-containing butyl rubbers are used in a number of grafting reactions for tire applications and adhesives. Other uses for butyl rubber are automotive mechanical parts (due to the high damping characteristics of butyl), mastics, and sealants.55... 

Lubricating oils, sealants copolymerized with 0. -2.S mol% isoorene to produce Butyl rubber for tire inner tubes and inner iiners of tubeless tires. 

Kalar . [Hardman] Butyl rubber used in sealants, coatings, caulks, as green enhancer for uncured butyl robber compositions. 

Butyl rubber/isobutylene It is elastomeric—it stretches Additive for hot-melt adhesives, window sealants, and pressure-sensitive adhesives... 

Butadiene, 2-methyl-, polymer with 2-methyl-1-propene Butyl rubber Isobutylene/isoprene co-polymer Kalar 5214 Kalat 5263 Kalene 800 2-Methyl-1,3butadiene polymer with 2-methyl-1-propene Poly(isobutylene-co-isoprene). Cross-linked butyl composition produces nonsagging butyl-based sealants, e.g., automotive windshield tape, hot melt sealant as base for butyl mastics Viscosity (Mooney, ML 1- 8,100°) = 42-52. Hardman. 

The above criteria were employed to select several commercially supplied Class PS elastomers for laboratory screening by employing selected tests taken from National Bureau of Standards NBSIR 77-1437(j4) and ANSI/ASTM D-3667-78 specifications for "Rubber Seals Used in Flat-Plate Solar Collectors". Four silicone, three EPDM, two fluorocarbon, three epichlorohydrin, one ethylene-acrylic, one polyacrylic, one chlorosulfonated polyethylene, one bromobutyl and two butyl rubbers were studied in these screening tests. These materials are identified in Table I and those compositions which were revealed by their manufacturers are shown in Table II. Undoubtedly some materials which should have been included were omitted however, we hope that this sampling will provide an indication of the applicability of a wide range of materials for use as sealants in thermal solar collectors. 

One of the better heliostat sealants was found to be a butyl rubber, Adcoseal B-100. This module incorporated a design modification a 1/16" butyl rubber pad bonded between the mirror and the polystyrene foam substrate. The module looked extremely good after 12 months accelerated aging. A sealant of this type must be used with some degree of caution because butyl rubbers are not normally considered as thermally stable or UV resistant as silicones. 

Typical representatives of this group are non-drying sealants based on butyl rubber, polyisobutylene, ethylene-propylene rubber in combination... 

The life expectancy of polyurethane sealants has been considered to be 10 years while that of butyl rubber, acrylics, polysulfides and silicones has been stated to be 15 years. Additional information on application techniques2 l and tests for sealants is readily available. 

As a result of its very low gas permeability, butyl rubber is used predominantly in the inner tubes of tires and inner liners for tubeless tires. Some of the other uses of butyl rubber include sealants, adhesives, hoses, gaskets, pads for truck cabs, bridge bearing mounts, and other places where vibration damping is important. 

Poly sulfide rubber was first produced in 1929, and the liquid polymers were used in sealants and as flexibilizers for epoxy adhesives around 1950. In 1952 the polysulfide sealant was introduced to the construction industry [11, p. 74]. In the 1950s the first butyl rubber caulks appeared in the construction market [11. p. 108] and latex caulks [vinyl acrylic and poly(vinyl acetate)] appeared sometime after 1956. 

Early adhesive uses of butyl rubber generally consisted of solvent-based dispersions, or tape and rope extrusion of formulated solid rubber. Extensive use was made of butyl rubber s inherent tackiness in highly saturated grades of the polymer to make pressure sensitive tapes and precoated films. The polymers are also extensively used as major components of hot-melt adhesives, solid rubber sealing tapes, and caulking grades of sealants and mastics, of which most were high solids content solvent-based formulations. 

The wide variety of grades available provides for an extremely diverse array of properties that can be developed for butyl rubber adhesives and sealants. However, the following general properties apply to varying degrees. 

Chem. Descrip. Hydrogenated C5 aliphatic hydrocarbon resin Uses Tackifier, processing aid for adhesives, caulks, sealants, elastomers, polymers, and other resins ind. EVA, amorphous polyolefins, PE waxes, butyl rubbers, inks, paints, varnishes, textile sizes in dry-deaning food pkg. adhesives... 

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