Neoprene rubber types

In an acetone extract from a neoprene/SBR hose compound, Lattimer et al. [92] distinguished dioctylph-thalate (m/z 390), di(r-octyl)diphenylamine (m/z 393), 1,3,5-tris(3,5-di-f-butyl-4-hydroxybenzyl)-isocyanurate m/z 783), hydrocarbon oil and a paraffin wax (numerous molecular ions in the m/z range of 200-500) by means of FD-MS. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out (Chapter 2). The method of Dinsmore and Smith [257], or a modification thereof, is normally used. Mass spectrometry (and other analytical techniques) is then used to characterise the various rubber fractions. The mass-spectral identification of numerous antioxidants (hindered phenols and aromatic amines, e.g. phenyl-/ -naphthyl-amine, 6-dodecyl-2,2,4-trimethyl-l,2-dihydroquinoline, butylated bisphenol-A, HPPD, poly-TMDQ, di-(t-octyl)diphenylamine) in rubber extracts by means of direct probe EI-MS with programmed heating, has been reported [252]. The main problem reported consisted of the numerous ions arising from hydrocarbon oil in the recipe. In older work, mass spectrometry has been used to qualitatively identify volatile AOs in sheet samples of SBR and rubber-type vulcanisates after extraction of the polymer with acetone [51,246]. 

Fluorocarbon derivative rubbers Isobutylene-isoprene rubbers Isocyanate type rubber Isoprene rubbers, synthetic N-type rubber Neoprene Nitrile type rubber Nitrile-butadiene rubbers Polybutadienes... 

Phenylene oxide-based resins (Noryl ) epoxy, polyisocyanate, polyvinyl butyral, nitrile rubber, neoprene rubber, polyurethane rubber, polyvinyUdene chloride, and acrylic. Polyethylene-nitrile rubber, polyisobutylene rubber, flexible epoxy, nitrile-phenolic, and water-based (emulsion) adhesives. Polystyrene for these foams (expanded polystyrene (EPS)), aromatic solvent adhesives (e.g., toluol) can cause collapse of the foam cell walls. For this reason, it is advisable to use either 100% solids adhesives or water-based adhesives based on SBR or polyvinyl acetate. Specific adhesives recommended include urea-formaldehyde, epoxy, polyester-isocyanate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and reclaim rubber. Polystyrene foam can be bonded satisfactorily with any of the following general adhesive types ... 

Thiurams and carbamates have most commonly been responsible for the type-IV reactions due to rubber gloves. Mercaptobenzothiazole was the first benzothiazole accelerator used in gloves, but other derivatives can also be used. The reports on sensitization to thiourea compounds from rubber gloves are few and, for the most part, involve gloves made of neoprene rubber which may also contain diphenyl-guanidine (Estlander et al. 1994a, 1995 Kanerva et al. 

The polychloroprene rubber preferred is the Neoprene W type. Neoprene G would perhaps give slightly superior properties, but W-type gives the best compromise between properties and processability, (ref. 3). A special low-viscosity grade, similar to W-Ml is used. The compound contains approximately 40 phr high abrasion furnace (HAF) black to reinforce it. 

This compound also uses Neoprene W type polychloroprene rubber. The compound, though coloured black with a few parts of carbon black is mainly filled with silica, which is a reinforcing mineral filler. The silica also helps to bond the rubber to the steel cords other ingredients added for this purpose include cobalt naphthenate. A commonly used system for this purpose is one comprising resorcinol and hexamethylene tetramine (HMT) which acts as a formaldehyde donor to form a phenolic resin in situ, but this is not suitable for Neoprene compounds because resorcinol is a fast accelerator for Neoprene vulcanization and interferes with its processing safety. 

The Guide to Grades, Compounding and Processing of Neoprene Rubber compiled initially by J. C. Bament lists the major dry type applications and starting formularies for compoimds to meet the specific end uses (98). 

Temperature is a major consideration from a fire protection standpoint. Flame propagation must be avoided. Belt conveyors are usually restricted to 150°F. Rubber belts have the highest rate of flame propagation, while the ignition characteristics are similar for neoprene, rubber, and polyvinyl chloride materials. With hot materials or in hot atmospheres, screw conveyors, vibrating units, or types of pan conveyors are preferred. 

Ball sealers are available in different materials, but usually of a rubber type. Rubber-coated neoprene (RCN) is the most common. Selection depends on density and temperature limit requirements. 

Adhesives used to bond acetal homopolymer (Dehin ) to itself and to other materials, such as aluminum, steel, natural rubber, neoprene rubber, and Buna rubber, include polyester with isocyanate-curing agent, rubber-based adhesives, phenohcs, epoxies, modified epoxies, and vinyls. Solvent cementing cannot be used unless the surfaces are specially roughened, because of the high solvent resistance of this material [23]. Other adhesive types sometimes used are resorcinol, vinyl-phenolic, ethylene vinyl acetate, cyanoacrylates, and polyurethane. 

The demands on insulating materials in soil and fresh water are relatively low. Anodically evolved oxygen makes the use of aging-resistant insulating materials necessary. These consist of special types of rubber (neoprene) and stabilized plastics of polyethylene, and polyvinylchloride, as well as cast resins such as acrylate, epoxy, polyester resin and many others. 

With the shear-type coupling, the elastomeric element may be clamped or bonded in place, or fitted securely to the hubs. The compression-type couplings may be fitted with projecting pins, bolts, or lugs to connect the components. Polyurethane, rubber, neoprene, or cloth and fiber materials are used in the manufacture of these elements. 

The first synthetic rubbers to be commercially available in United States were Thiokol (1930) and Neoprene (1931). Both of these are still being produced commercially because they have special properties that are not matched by natural rubber. Various types of synthetic rubbers were introduced during (1939-43) World War II. After world war, stereo rubbers have been made using stereo specific catalysts. 

Chemical Type Viton Butyl Rubber PVA Neoprene Nitrile PVC Latex... 

Polymeric Materials. The single-ply membranes are made from a wide variety of polymers. The following is a brief description of those polymers and their characteristics. There are three thermosetting-type elastomeric membranes as of this writing (1996) neoprene, CSPE, and EPDM. Neoprene is still used where oil resistance is needed. For instance, Hydrotech uses neoprene flashings, the base of which is hot-set in rubberized asphalt (see Elastot rs, synthetic-polychloroprene). 

Although benzyl alcohol is listed as an approved antimicrobial under the FDA guide, there are many factors that should be considered before including it in an oral solution formulation. There are numerous reports of adverse reactions to benzyl alcohol following IV and intrathecal administration and it is not recommended for use in premature infants. Benzyl alcohol is incompatible with methylcellulose and is also known to be incompatible with a number of container types. For example, a 2% aqueous solution in a polyethylene container, stored at 20°C, may lose up to 15% of its benzyl alcohol content in 13 weeks. However, it is only slowly sorbed by closures composed of natural rubber or neoprene. 

Certain types of synthetic rubbers such as neoprenes and hypalons when suitably compounded with asbestos fillers are flame resistant and give passive fire protection. This safety aspect is a key priority in many chemical and engineering industries as well. These fire protection technologies are used to protect structures and equipment against all types of fires including the extreme conditions of a jet fire. 

These are based on polymer types. Neoprene, acrylonitrile, silicone rubbers and thiokol rubbers are to be chosen. 

These same types of compounds are also more resistant to many acids at high temperatures than natural rubber can handle. Neoprene should not be used in parts which are bonded to metal for hydrochloric acid service because acid migration can cause failures. For hydrochloric acid service ebonite lined mild steel equipment is the correct selection. Ebonites form rubber hydrochloride film in contact with natural rubber and this film is the protective layer against corrosion. 

Fluoroboric acid is produced commercially by the reaction of 70% hydrofluoric acid with boric acid. Fluoroborate solutions must be treated like hydrofluoric acid and handled in corrosion resistant equipment consisting of polyethylene, polypropylene, or neoprene-type rubber. The major use of fluoroboric acid is as an intermediate in the preparation of fluoroborate salts. It is also used in electroplating aluminum and in metal cleaning operations. 

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