Vulcanizable elastomers

AH of the polyether elastomers, like other vulcanizable elastomers, can be compounded with processing aids, fillers, plasticizers, stabilizers, and vulcanizing agents to make useful mbber products. A typical compounding recipe for epichlorohydrin elastomer is as follows ... 

Sulfur-vulcanizable elastomers have been prepared that are designed to reduce hysteresis in tires by reducing the number of polymer free ends. The method for this preparation entails anionically preparing poly(styrene-co-butadiene) using a lithium thioacetal initiator followed by incorporation of a vulcanization agent into the elastomer terminus. 

Plastics materials, synthetic resins, and non-vulcanizable elastomers... 

It is part of a homologous series of linear unsaturated polymers that are termed polyalkenamers. Polypentenamer is an interesting member of this series because cyclopentcne is economically available from petrochemical by-products and because the polymer is a readily vulcanizable elastomer (since it contains residual C—C double bonds cf. p. 10). 

DVEA dynamic vulcanizate elastomer alloy EDC Eurocomp design code... 

The experimental experience showed that the standard deviation is usually much smaller for OtN compared to aiu, why the use of notched specimens should be preferred. When testing mbber vulcanizates (elastomers), only notched specimens can deliver a result at all because of the mostly large deformation. For thermoplastic films, especially with very small thickness, the dumbbell specimen type can be more useful, otherwise also notched specimens should be preferred. Besides the testing of elastomers and films, for which the Charpy test caimot be applied, also testing of rigid thermoplastic materials/specimens is generally possible. 

Cationic copolymerization of i3-pinene with about 20% isobutylene produces impact-resistant thermoplasts, and vulcanizable elastomers when more than 90% isobutylene is used. 

Cold grades, that is, one-component room temperature vulcanizable elastomer grades (RTVs) dominate in the case of liquid silicone rubbers. In these cases, the rubbers are branched poly(dimethyl siloxanes) with silanol end groups that can be cross-linked with tetrabutyl titanate or methyl triacetoxy silane. The cross-linking starts on contact with the humidity in the air, whereby in the case of methyl triacetoxy silane, for example, acetic acid is liberated and the methyl trihydroxysilane produced reacts with the silanol groups of the polymer ... 

Examples of vulcanizable elastomers include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene monomer-rubber (EPDM), butyl rubber (HR), polychloroprene or neoprene (CR), epichlorohydrin rubber (ECO), polyacrylate rubber (ACM), millable polyurethane rubber, silicone rubber, and flu-oroelastomers. Examples of thermoplastic elastomers include thermoplastic polyurethane elastomers, styrenic thermoplastic elastomers, polyolefin-based thermoplastic elastomers, thermoplastic polyether-ester (copolyester) elastomers, and thermoplastic elastomers based on polyamides. 

In this chapter, we discuss both vulcanizable elastomers and thermoplastic elastomers. There is another, albeit narrow-niche type (i.e., liquid rubbers), which we will not discuss here. Our focus will be on the various types of elastomers, their properties, applications, and processing. 

A large number of chemically different conventional, vulcanizable elastomers exist. 

Dynamically vulcanized, elastomeric thermoplastic alloys or TPVs display properties as good as or even better than the block copolymers, viz., a high degree of rubber elasticity yet good melt processability. The main advantages of the thermoplastic vulcanizate elastomer blends over the uncured thermoplastic/elasto-mer blends are... 

These dienes, along with ethylene and propylene, are used to make EPDM, a sulfur-vulcanizable elastomer. Generally, EPDM contains 25-60 wt% propylene and 1-5 wt% diene, and is completely amorphous. Metallocene catalysts have inherent advantages in EPDM pol5unerization, the most important of which are the ability to incorporate large amoimts of a-olefin with ease and the avoidance of long ethylene sequences that lead to crystallinity. Catalysts that appear to have found commercial application in EPDM include mono-Cp catalysts such 12 (207) and 14 (208). 

The condensation of silanols is also catalyzed by metal compounds such as cobalt naphthenate and stannous octoate. Such compounds are used in connection with room-temperature vulcanizable elastomers (Section 15.6.2.6) and resins (Section 15.6.3). Their mode of action does not appear to have been investigated in any detail. 

Natural rubber with over a century s use in many different products and markets will always be required to attain certain desired properties not equaled (to date) by synthetic elastomers. Examples include transportation tires, with their relative heat build-up resistance, and certain types vibrators. However, both synthetic TSE and TPE have made major inroads in product markets previously held only by natural rubber. Worldwide, more synthetic types are used than natural. The basic processing types are conventional, vulcanizable, elastomer, reactive type, and thermoplastic elastomer. 

Because of their thermoplastic nature, many processes can fabricate TPEs. The number of applications is rapidly increasing, as they often displace conventional vulcanizable elastomers (TSEs). TPEs offer a combination of strength and elasticity as well as exceptional processing versatility. They present creative designers with endless new and unusual product opportunities. 

NBR can and has been used to modify a variety of plastics, but the most widely used blend is that with PVC. With this plastic it is possible to have two distinct types of blend ratios, firstly that where the PVC predominates and the resultant blend is processed as a thermoplastic and secondly that where the NBR predominates and the blend is subsequently processed as a vulcanizable elastomer. 

Synthetic rubber), for example, acrylate, acrylate-butadiene, butyl, ethylene-propylene, chloroprene, ethylene-propylene diene, latex, neoprene, nitrile-butadiene, polyisobutylene, polysulfide, silicone, styrene-butadiene, styrene-isoprene rubber thermoset vulcanizable elastomers thiol rubber urethane... 

G.K. Cowell and D.J. Cherry, Metal deactivators as adhesion promo-tors for vulcanizable elastomers to metals, US Patent 3994987, assigned to Ciba-Geigy Corporation (Ardsley, NY), November 30,1976. 

The development of chlorosulfonated polyethylene (CSM) began during the early 1940s by Du Pont as part of the wartime effort using low cost ethylene and attempting to create a vulcanizable elastomer with the electrical and chemical properties of polyethylene [1]. 

Thermoplastic polyolefin elastomer/ polyolefin blend elastomer Thermoplastic vulcanizate elastomer TPV TPR, Santo-prene, Geolast, Vyram, Nex-prene, Alcryn... 

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