Butyl sealant process

One-part solvent-releasing butyl sealant formulation, 22 43t One-part urethane sealants, 22 36-37 One-pass clarifier, 22 61 One-photon absorption, 77 455 One-pot oxidation polymerization, 23 713 One-stage separation plants, 75 840 One-step cameras/processors, 79 276-278 One-step Ziegler process, 77 715-718 One-way memory, of shape-memory alloys, 22 341, 345-346... 

Reactive fibers, 9 486-489 Reactive flame retardants, 11 474-479 brominated, ll 475-477t Reactive gases, 13 456 Reactive groups, types of, 9 178 Reactive hot melt butyl sealants, 22 44 Reactive hot melt polyurethanes, 22 37-38 Reactive hot melt silicones, 22 35 Reactive ion-beam etching (RIBE), 22 184 Reactive ion etching (RIE), 20 278 22 183 of lotus effect surfaces, 22 120 Reactive lead alloys, 14 779 Reactive liquid metal infiltration process, 16 168... 

Newton, M.V. et al, 1986, "Butyl Sealants Formulating, Developing, Processing", ibid, pp 25-75. 

Kilchesty, AA., 1986, "Oleo Resinous and Oil-Base Caulking Compounds", ibid, pp 13-23. Newton, M.V. et al, 1986, "Butyl Sealants Formulating, Developing, Processing", ibid, pp 25-75. 

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. 

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... 

Uses Butyl mbber base for elastic sealants requiring more resistance to flow or sag processing aid, grn. str. enhancer for butyl and EPDM compositions al in solv. release coatings, caulks, architectural glazing tapes Properties Amber pellets sp.gr. 0.92 vise. (Mooney) 58-68 (ML1+3 260 F) tens. str. 150 psi tens, elong. 1000% hardness (Shore A) 15 Kalene 800 [Elementis Spec. Petf. Polymers]... 

Uses Butyl mbber in sealants, coatings, elec, encapsulating compds., and conformal coalings incl. moisture-impermeable coatings, marine and construction sealants, elec, encapsulants, pressure-sensitive adhesives tackifier for pressure-sensitive adhesives processing aid, adhesion promoter... 

Acrylic sealants are water-based but they may also contain ethylene and propylene glycols, mineral spirits and mineral oil. There are also solvent-based aerylie sealants which contain substantial amounts of solvents sueh as mineral spirits, toluene and xylene. Polysulfide sealants usually contain toluene but methyl ethyl ketone is also used. The group of class B sealants contains substantially more solvents (up to 40% by volume) but there are some exceptions. PVC sealants are based on plastisols and they ean be made without solvents. Butyl rubber based sealants usually eontain hydroearbons (Q-Cn). Styrene-buta-diene-styrene based sealants usually have a large amount of solvents seleeted from a group including toluene, heptane, hexane, methyl ethyl ketone, isobutyl isobutyrate, n-amyl acetate, n-amyl ketone. They are usually processed in solvent mixtures. Polyehloroprene is usually dissolved in a mixture of solvents ineluding ketones or esters, and aromatie and aliphatic hydrocarbons. The list includes naphtha, hexane, aeetone, methyl ethyl ketone, benzene, and toluene. 

Intermediate movement accommodating sealants include solvent-based and emulsion-type acrylic systems, higher quality butyl/PIB blends, neoprene and styrene-butadiene (SBR) based compounds. These have sufficient movement tolerance to be used in joints subject to both settlement and thermally induced movement across the sealant. These intermediate type systems cure by means of solvent evaporation with some auto-oxidation, or a mixture of the two processes. 

Many other polymeric additives are used in butyl and PIB adhesives and sealants. Most worthy of mention are factice, which can lower cost, improve processing, and reduce stringing amorphous polypropylene, which can reduce cost and improve processing as well as impart thermoplastic character various waxes, which function in much the same manner as amorphous polypropylene and asphalt, again for lower cost. 

Premasticated butyl cutbacks for the sealant industry are also available, as are a series of depolymerized butyls, to improve compounding and processing ease. Chlorobutyl rubbers are also produced these have found limited use in sealant formulations, mostly in tapes. 

Tackifiers (A.S.C., 1986 Dick, 1987) - Tackifiers are used in certain types of adhesives and sealants to greatly improve initial adhesive strength (tack strength) on contact with an adherend surface before a stronger bond is formed later during the cure process. Elastomers such as natural rubber and butyl rubber, and thermoplastic hot melt systems all have low tack and require tackifiers to adhere well to polar substrates such as glass, ceramics, masonry and metal surfaces. 

Several other compositions that are commonly classed as crosslinked butyl rubbers are available, although they are not listed as such by their manufacturers, in The Synthetic Rubber Manual—8. They are made by partially curing compounds of unmodified butyl rubber containing additional materials such as fillers, plasticisers and resins they too are used primarily in caulks and sealants. They do not offer the high levels of resistance to sag and flow that are achievable with the terpolymers, but they are much easier to process. 

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