Thermosets sealants

Thermoset polyurethanes, 25 460-461, 476 Thermosets, 10 456, 20 390 Thermoset sealants, 22 35 Thermosetting-encapsulation compounds, 17 839... 

Within solvent release type thermosetting sealants, there are Neoprene, hutadiene-styrene, chlorosulfonated polyethylene, EPDM, and silicones. Solvent release types constitute the largest variety of sealants and are composed of three parts (1) the liquid portion of the compound which is the basic non-volatile polymer/elastomeric vehicle, (2) the pigment component, and a (3) solvent or thinner component used to ease the process and to control the thickness. The sealant is cured and its required viscosity is controlled by the evaporation of solvent. 

Thermosetting resins have been used extensively in industry for applications such as structural adhesives, composites, RIM, coatings and sealants which need to resist severe service conditions. Thermosetting resins are generally composed of low molecular weight oligomers which allow fabrication convenience. 

Because PIB is fully saturated, it is cured as a thermoset elastomer through inclusion of about l%-2% isoprene that supplies the needed double bonds used in the curing process. Other materials including brominated paramethyl styrene are replacing isoprene for this use. PIB is also used in sealing applications and medical closures and sealants. 

Thermosets A number of thermosets have been used as adhesives. Phenolic resins were used as adhesives by Leo Baekeland in the early 1900s. Phenolic resins are still used to bind together thin sheets of wood to make plywood. Urea resins have been used since 1930 as binders for wood chips in the manufacture of particle board. Unsaturated polyester resins are used for body repair and PUs are used to bond polyester cord to rubber in tires, and vinyl film to particle board, and to function as industrial sealants. Epoxy resins are used in the construction of automobiles and aircraft and as a component of plastic cement. 

Epoxy is a synthetic polymer which is used in a variety of ways. Strengthened with some form of filler it is used for such purposes as aircraft manufacture. In connection with organics, it is used for items such as imitation scrimshaw, as it can be shaped in pliable moulds which can be peeled off after the polymer has set, minimising the marks left by the mould (Fig. 3.10). It is also used for coatings, sealants and adhesives. It is thermosetting. 

In this book I have confined discussion to those polymeric materials which are cured by chemical reaction and which have found widespread application in the construction industry. As such, the book covers materials based on epoxies, polyurethanes, silicones, polysulphides, alkyds and polyesters. In addition, there is a chapter on hybrid polymer systems and one on acrylics. It is true that acrylic emulsions are not strictly thermosetting polymer systems, but their widespread use and importance made their exclusion difficult. These materials find use as coatings, sealants, adhesives, grouts, flooring compounds, repair compounds and waterproofing agents. 

THERMOSETTING POLYMERS IN CONSTRUCTION APPLICATIONS Table 6.4 Properties of one-component and two-component silicone sealants... 

Other substrates such as graphite powder and mica are also coated with nickel. Silver is the most conductive metal, being almost 5 times less resistant than nickel. Silver and copper have very similar conductivities but copper is easily oxidized and reacts with acids readily which affects its performance in polymeric systems. The PQ Corporation and Potters Industries, Inc. have developed a whole range of products which are silver coated. Their application is for conductive thermosets, gaskets, sealants, adhesives, paints, coatings, inks, and EMI control applications. Its use in these products saves 1/3 of weight of conductive material. 

This chapter will deal with the chemistry and applications of epoxies, phenolics, urethanes, and a variety of current vogue high-temperature polymers. Applications in fiber-reinforced plastics will be discussed in the individual sections on resin chemistry where appropriate. Separate sections will deal with adhesives and sealants. Adhesives are most important because, as early history demonstrates, they led the way to the application of resins in aerospace. A section is also included on silicone and polysulfide sealants. Although these materials are elastomers rather than resins, no discussion of aerospace polymers would be complete without some mention. Some major thermosetting polymers have been omitted from this review. Among these are the unsaturated polyesters, melamines, ureas, and the vinyl esters. Although these products do find their way into aerospace applications, the uses are so small that a detailed discussion is not warranted. 

Emtal . [Engelhard] Talc filler, rein-forcer for thermosets, thermophutics, thermoplastic elastomers in caulks and sealants, dry-wall comp., adhesives, printing inks, paints, metal primers dusting agent few tacky rubber compds. 

Gama-FIL [Georgia Marble] Calcium carbonate filler for use in plastics, BMC/SMC, paint, caulks, sealants, adhesives, paper, foam urbane, niodi-fied acrylics, filled thermosets/thermo-plastics, and rubber. 

Sachtolith . [Sachtleben Chemie GmbH Ore Chem.] Zinc sulfide white pigment for thermoplastics, thermosets, elastomers, textile fibers, paper, sealants, lubricants. 

While most of the subjects discussed up to this point involve injection molding or extrusion applications, there are a considerable number of other applications where polymer blend technology is and will be employed including adhesives, sealants, coatings, and thermosetting systems, polymeric membranes, and water-based polymers. 

OTHER COMMENTS used as a solvent for cellulose ethers and esters, dyes, and natural resins used in the manufacturing of phenolic resins and dark-colored thermosetting resins chemical intermediate for tetrahydrofurfuryl alcohol also used in the manufacture of wetting agents, furan polymers, corrosive resistant sealants and cements useful as a liquid propellant. 

CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Pigment, filler, extender, reinforcer, and bodying agent in plastics (thermoset polyester, PVC), vinyl plastisols, rubber (NR, SBR, CR, HR), adhesives, sealants, caulks, paints, coatings, printing inks, extrusions, moldings, belts, footwear chem. reagent, carrier, calcium source Features Nonabrasive controlled particle size easily dispersed Properties Powd. 0.8 p median particle size 0.015% on 325 mesh ... 

CAS 471-34-1 EINECS/ELINCS 207439-9 Uses Reinforcing agent, filler tor exterior/interior paints/coatings where flat and med. gloss surfs, are required, paper coatings, adhesives, caulks and sealants based on acrylic, polyolefin, silicone, and PU, plastics (polyolefin, PU, compr. and in], molded, plastisols), rubber (NR, SR, latex), thermosets (BMC/SMC, pultrusion) extender tor wh. and colored pigments... 

Chem. Descrip. Calcium carbonate CAS 471-34-1 EINECS/ELINCS 207439-9 Uses Filler for plastics, PVC, polyolefins, polyesters, BMC/SMC, paint, caulks, sealants, adhesives, paper, foam urethane, modified acrylics, filled thermosets/thermoplastics, and rubber Features Improves impact str., dimensional stability Regulatory NSF approved for potable water materials Properties Wh. powd. 2 avg. particle diam. 99.9% finer than 8 0.15% sol. in water sp.gr. 2.70-2.71 dens. 22.57 Ib/gal bulk dens. 38 Ib/tP (loose) oil absorp. 23 01 cc/100 g brightness (Hunter) 95 ref. index 1.6 pH 9.5 (sat.) hardness (Mohs) 3.0 Toxicobgy Nontoxic Camel-TEX [IMERYS]... 

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