Cured Urethane Rubber

There is only one commercial series of isocyanate-cured urethane rubbers, namely the Urepan series of Bayer. Urepan 600 is a polyester derived from diethylene glycol adipic acid and toluene diisocyanate. The ratio of polyester to diisocyanate is such that hydroxyl groups, not isocyanate groups, are situated at the ends of the chains. The chain length is kept 

EFFECT OF PLASTICIZER TYPE ON AGEING CHARACTERISTICS OF URETHANE ELASTOMER AGED IN AIR AT 1 00°C FOR 4 DAYS 

BASE FORMULATION USED TO EVALUATE FILLERS IN MILLABLE POLYURETHANE ELASTOMER 

Cure carbon black filled rubber, 60 min at 140X non-black filled rubber, 90 min at 140X 

EFFECT OF CARBON BLACK TYPES AND PROPORTIONS ON URETHANE ELASTOMER PROPERTIES 

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EVA-based Rubber-based Moisture-cure urethane... 

Organic zinc-rich primers are based on epoxy/polyamides, high-molecular-weight linear epoxies, moisture-cured urethanes, high-styrene resins, chlorinated rubbers and epoxy esters. In this type of primer zinc is covered with a monomolecular layer of the binder which facilitates the adhesion of the film to the substrate. 

MOCA n. DuPont s trade name for methy-lene-bis-o-chloroaniline, much used until about 1980 as a curing agent for urethane rubbers and epoxy resins, prior to its being declared to be a carcinogen by OSHA. 

Aerobic adhesives (Dymax Corporation) Hydroxyfunctional monomers, dibasic acid, perester, dihydropyridine, urethane rubber and transition metal salt Very fast curing and less sensitivity to inhibition by atmospheric oxygen... 

Polyurea Polyurethane Porosity Post cure glycols, glycerol, and polyesters. A polymer containing the urea group -NH-CO-NH-. A polymer containing the urethane group -NH-CO-O-. The presence of numerous small cavities. Heat treatment to which a cured or partially cured thermosetting plastic or rubber composition is subjected to enhance the level of one or more properties. 

Millable urethanes are processed on standard rubber-processing machinery. They may be either peroxide or sulfur cured. The sulfur-cured varieties have some chemicals added to enable sulfur curing to take place. These polyurethanes also have the properties of castable polyurethanes but need to be processed on standard rubber machinery. 

There is wide variety of vulcanisation agents and methods available for crosslinking rubber materials including peroxide, radiation, urethane, amine-boranes, and sulfur compounds [20]. Because of its superior mechanical and elastic properties, ease in use, and low cost, sulfur vulcanisation is the most widely used. Although vulcanisation with sulfur alone is not practical compared to the accelerated sulfur vulcanisation in terms of the slower cure rate and inferior physical properties of the end products, many fundamental aspects can be learned from such a simply formulated vulcanisation system. The use of sulfur alone to cure NR is typically inefficient, i.e., requiring 45-55 sulfur atoms per crosslink [21], and tends to produce a large portion of intramolecular (cyclic) crosslinks. However, such ineffective crosslink structures are of interest in the understanding of complex nature of vulcanisation reactions. 

Commonly used adhesives include epoxy, rubber, acrylic or vinyl emulsions, and urethanes. Epoxies are high-priced, but they have better chemical resistance and durability than the others, and they have dominated the market in outdoor applications. Significant advantages of the epoxy-based adhesives are that they have no solvents and, therefore, exhibit little shrinkage. They cure relatively fast and, therefore, are not as exposed to inclement... 

Mercapto Epoxy, sulfur cure rubbers, urethane, polysulfide... 

All of the commercial epoxy adhesives presented in App. B bond well to aluminum and to a wide variety of other materials. Sell22 has ranked a number of aluminum adhesives in order of decreasing durability as follows nitrile-phenolics, high-temperature epoxies, elevated-temperature curing epoxies, elevated-temperature curing rubber-modified epoxies, vinyl epoxies, two-part room temperature curing epoxy paste with amine cure, and two-part urethanes. 

Asphalt, unmodified Coal tar Coal tar— epoxy Coal tar— urethanes Epoxy phenolic- baked Epoxy amine- cured Epoxy ester Furfuryl alcohol Phenolics, baked Polyesters (unsatu- rated) Polyvinyl chloracetates Vinyl ester Urethanes Vinylidene chloride Chlorinated rubber... 

MAJOR USES Used in the manufacture of azo dyes, rubber and plastic, printing ink, textiles, plastics and crayons used as a curing agent for polyurethane elastomers, isocyanate containing polymers and solid urethane plastics used as an intermediate for the detection of gold and production of pigments. 

OTHER COMMENTS used as an intermediate in the preparation of polyurethane foams, elastomeric fibers, and polyamides used in industry as a curing agent for epoxy resins and urethane elastomers, and as a corrosion inhibitor for iron useful in the determination of tungsten and sulfates has also been used in the preparation of azo dyes, as a rubber processing chemical, and as an epoxy resin hardening agent. 

Table 15-11 gives the physical properties of a urethane elastomer compared with cured natural and synthetic rubbers. One outstanding property of urethane elastomers is resistance to abrasion. 

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