Termonomers, EPDM

A specially developed titanium-based catalyst has been used in the suspension process for EPM and EPDM where the termonomer is low-boiling. The advantages claimed, in addition to those characteristic of the suspension process, are better structural control and high catalyst efficiency, resulting in a high-purity product without requiring catalyst removal.51... 

JSR Corp. Ethylene propylene rubber (EPR/EPDM) Ethylene, propylene, termonomer Solution process. Many (jades of EPM/EPDM with excellent characteristics 3 1995... 

Mitsui Chemicals, Inc. Ethylene-propylene rubber Ethylene, propylene, termonomer EPM/EPDM process uses solution polymerization with Ziegler catalyst 1 1994... 

The model compound (2-ethylidene-norbornane, NB) of the reference dienic termonomer ENB is less reactiw toward BPO than compounds (III,a) or (VII,a) because AIBN attacks NB only after proltmged reaction times (Fig. 8). This result explains the experimental observation described by Meredith according to which 04B-EPDM cannot be palled by SAN in the presence of AIBN. In contrast, Hp. 6 and 7 allow us to predict that EPTMs omtaining linear conjupted unsaturatitms can be pafted even in the pre ce of the less favorable AIBN. 

Cro -Iinking efficiency of UI)-EPTM ( ) and ENB-EPDM ( ) as function of termonomer content. Conditions dicumylperoxide =... 

Another calculation was made in order to distinguish between the amount of t-butoxy radical reacting with ethylene-propylene units and that reacting with the unsaturations of some terpolymers. The results (Table 12) indicate that there is al-wsys a significant amount of t-butoxy radicals which react with the H atoms of the saturated back-bone, while in the case of (III)-EPTM 34% of (CH3)3C0 reacts with flie unsaturation when the termonomer content is only 0.1 M. The sune result k achieved in the case of ENB-EPDM when the termonomer content is four-fold end hence agrees with the experimental data of Fig. 11. However, the formation of abundant amounts of tertiary alkyl type radkals, e.g. CH2-C(CH3)-CH2, when the termonomer concoitration is low, explain the poor yield of grafting... 

The introduction of sulfonate groups into EPDM occurs via an electrophilic attack of the sulfonation reagent on the unsaturation in EPDM. Many termonomers can be copolymerized with ethylene and propylene to produce EPDM s with a variety of residual olefinic types (II). All of the EPDM s in this study were produced from ENB. Since the incorporation of ENB into the polymer chain during copolymerization... 

Copolymerization of ethylene with propylene results in a random, noncrystalline copolymer that is a chemically inert and rubbery material. EPM is a saturated copolymer that can be cross-linked through the combination of the free radicals generated by peroxides or radiation. To incorporate sites for vulcanization, an unsaturated terpolymer can be prepared from ethylene, propylene, and a small amount (3 to 9%) of a nonconjugated diene (EPDM). The diene is either dicyclopentadiene, ethylidene nor-bomene, or 1,4-hexadiene. The resulting unsaturated terpolymer can be vulcanized by traditional techniques. Each of the termonomers confers different characteristics on the final elastomer. 

Ethylene-propylene copolymers (EPDM) are, by their random copolymerization, amorphous in structure and therefore easily halogenated. EPDM has been chlorinated to improve its properties and cocurability with other rubbers. The chlorination was directed toward the termonomer dicyclopentadiene to form the allylic chloride (Schoen et al., 1975). In this manner, EPDM was chlorinated, and the resulting products had improved properties. 

The compositions for the more than 150 grades of EPDM elastomers are in the ranges of 40 to 90 mole % ethylene and 0 to 4 mole % diene [236]. Thus, the structure of a typical EPDM elastomer with ethyhdene norbomene as termonomer can be represented by the following structure ... 

Dolatkhani M., Cramail H., Deffieux A., Linear nonconjugated dienes from biomass as termonomers in EPDM synthesis,... 

The long established use of accelerated sulphur systems for vulcanization of general purpose rubbers has always led to a reluctance of rubber processors to accept alternative vulcanization systems unless this was absolutely necessary. This is not simply innate conservatism but as much due to the anticipation of problems of contamination of stocks during processing and of difficulties in reclaiming. For this reason modified ethylene-propylene rubbers were developed in which units from a third monomer were present and which provided unsaturation in the polymer (EPDM rubbers). These termonomers, invariably dienes, used in amounts of 3-8% of the total monomer weight are generally expensive, relative to more common monomers and adversely affect the price structure but nevertheless the EPDM type of rubber is now dominant over the EPM copolymers. 

The characterization procedures used with EPM rubbers are complicated by the presence of the termonomer unit in the EPDM rubbers. In spite of this there would appear to be little published on the effect of this unit on the results obtained for ethylene propylene composition ratio by infra-red techniques. 

On economic grounds the cost of the termonomer has been a significant factor as have certain aspects of production costs so that, at the time of writing the EPDMs are significantly more expensive than natural rubber and SBR. Technical problems such as the lack of building tack have proved a deterrent to their use in tyre applications which involve extensive assembly operations whilst problems of compatibility and covulcanization in the case of a far from impossible stock mix-up have also been significant. 

Recently a codimerization of ethylene and butadiene using various organometallic catalyst systems to give cw-1,4 hexadiene was found, equation (7-5). Hexadiene is a potential third component (or termonomer) of ethylene-propylene-diene-rubber [sometimes called ethylene propylene-terpolymer, EPT or EPDM (according to the ASTM)]. 

EPDM Ethylene-propylene-diene termonomer rubber ... 

Ethylene propylene copolymers (EPM) are made by Ziegler-Natta and metallocene polymerization and are the commercial mbbers with the lowest density. EPM cannot be vulcanized and thus is not reactive to peroxide curing. To introduce an unsaturated site suitable for crosslinking, a non-conjugated diene termonomer such as ethylidene norbomene, 1,4 hexaadiene or dicyclo-pentadiene, is employed to produce the mbber known as EPDM. Ethylene propylene diene mbber has small number of double bonds, external to the backbone, introduced in this way. In EPDM, the E stands for ethylene, the P for propylene, the D for diene and the M indicates that the mbber has saturated chain of the polymethylene type, properties of EPM and EPDM are ... 

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